Sunday, June 4, 2017

Magni Sfida / Guzzi PHM40 dyno graph

As alluded to in the Sport 1100 post, a graph from a Magni Sfida running an over 1000cc LM4/5 motor of some tune spec (no idea specifically) fitted with PHM40 carbs.  Which model of PHM40 I don't recall, it was 2008.  

With the 175 mains it came in with it would kill the engine if you held it open from 4,000 rpm - at 6,500 to 7,000 it would shut down, then come back.  As the plugs were very black I figured it might be momentarily fouling the plugs.  The dyno showed OMG rich - off the scale (under 10:1) by 3,500 rpm.  148 mains fixed it, but the mixture tapered in a straight line from 14:1 around 3,500 rpm to 12:1 by 7,500 rpm.

My suspicion now that I look at it is air bleed sizing, which is not adjustable in Dellortos.  So I was worried that I might see a similar thing with the Sport 1100, but also curious that the fact these carbs were made to suit this engine size and rpm range may mean they were different internally to whatever variant of PHM40 was on the Magni.  The problem of "the things you don't know you don't know" means sometimes you have no answers.  I don't know who you'd ask either.

Red is 175 main, blue 165, green 152, dark blue and yellow 148 (LH and RH samples).  A compromise is all that was available here.

Dellorto carb tuning on a Moto Guzzi Sport 1100, with some gearing and ignition rambling

Something I haven't done for 22 years - played with carb tuning on a Sport 1100.

We were dealers at Moto Italiano in 1995 when the Sport 1100 were released.  They ran poorly at low speed, and we tried a few things to fix them that didn't really work.  Looking back now I don't recall what we did, but I don't think we ever changed needles or needle jets.  Probably because it went into the "too hard" basket that you often get at a dealership when you're chasing warranty issues with no support or denial from the importer/warranty issuer.  It can be a very frustrating situation.  Plus I didn't really have much specific Dellorto tuning experience back then, nor the info required in the form that I'm going to use here.

So when I had someone ring and ask me to tune one I was a bit reluctant.  The story was that it used to run very nicely.  Then someone else had played with it, and now it didn't go so well.  The airbox had been removed and small pods filters fitted, and the jetting changed.  It was all a bit vague and I had the feeling I should have done what I knew at least one other person had done and found an excuse not to work on it.  Or just outright refused.  But I have this often trouble making sense of obligation to help people, and agreed.

The original airbox got a lot of blame for the poor low speed running back in the day, but one thing it did have was the somewhat unglamorous plastic ram tubes on the back of the carbs.  I don't recall how long they were, but looking at the available space and remembering what they looked like in my 1100i, I'd think they were around 150mm long.  When you start looking at inlet lengths and theory and how long stuff needs to be, it generally turns out that, on motorcycle applications, you just don't have the room.  The distance from the valve seat to the air entry is the length you're looking at, and for this engine running to 8,000 rpm maximum ideally it'd be in the 450mm range.  More than the available.  

I recalled Barry Jones of Italian Motorcycle Engineering playing with one back in the day, so I gave Baz a call to ask what he had done.  He'd been involved in one fitted with FCR carbs and on that they'd moved the carbs back an extra 50mm or so to give it some more length.  I thought it'd be easier to fit a ram tube of some sort, and went looking for something with a 52mm mounting ID.

I found these - Ram tubes - and figured they'd be as good a place to start as any.  Not too expensive being part of the consideration when you're trying ideas that might turn out to be crap.  I also needed filters, so got some of the Uni filter socks to go over them.

I had also asked Baz for any jetting recommendations.  His reply of K5 and 265 made me think about how you can often overlook a simple basis.  Lots of Ducati 900 bevels with PHM40 run the K4 needle and 265AB needle jet, and for Guzzi it seems to be the K5 needle and 265AB needle jet.  The original setup for the Sport 1100 is K18 and 266AB.  This one had K20 and 268AB.  I have a spreadsheet of Dellorto needles that makes it easy to compare them in an almost visual sense, and that's where I headed before I started changing things.

Well, the first thing I changed was the float height.  Set to 21mm when I started, I lifted the float level to 18mm.  This is done with the carb sitting on the air filter flange and the float pivoting about and above the spindle.  18mm is pretty close to as high as they would go and still give a readable setting, whereas the older PHM were more obvious at 18mm I recall.  Anyway, they were set and I moved on.  I don't use float level as a tuning variable.  I figure offering myself less possibilities for confusion is beneficial.

As was, the carb set up was 60/3 slide, K20 needle on the 3rd notch, 268AB needle jet, 162 main and 65 pilot.  Std spec on the Sport 1100 (Euro that we got anyway) was 60/5, K18@3, 266AB, 152 and 57.  The difference in the slides is the pump ramp - see my  Dellorto phf / phm pump ramp profiles piece for more info there.

Comparing the needles and needle jets can be confusing, but some years ago I made a spreadsheet for just this purpose.  The needle jets, like the Dellorto mains and pilots, are self explanatory - divide the number by 100 and you have the dimension in mm.  A 268 needle jet is 2.68mm, a 152 main is 1.52mm and a 57 pilot is 0.57mm.  On the needle jet AB denotes the physical design of the jet and what carb models it fits into.  Interestingly, the Keihin FCR carbs have only one needle jet size. They offer a vast array of needles varying in root diameter (steps of 0.01mm), taper and overall length to hit the required targets.

The Dellorto needles are numbered without reason as such.  All (afaik) K needles for the PHF/PHM carbs are the same overall length, being 73.5mm as I measured it.  Variables are the root diameter, tip diameter, taper length and number of clip grooves.  This chart shows the options.  It's a bit hard to read, due to the amount of info on it.  I didn't realise there were over 90 K needles - I have up to K30 on my spreadsheet.

Using the numbers I had found, I made a spreadsheet which gives needle diameter at distances from the tip in 2mm steps.  It seemed about the most logical way to do it, although now that I have done some more measuring on them and found the clip grooves are 1.25mm apart using 1.25mm may have made more sense.  The K5, which has 3 grooves, has the top of the clip grooves 2.75, 4.0 and 5.25mm from the top of the needle.  The K20, which has 4 grooves, has the tops of the grooves 1.75, 3.0, 4.25 and 5.50mm from the top of the needle.  Probably more accurate to measure from the bottom of the needle given that's how the taper is specified, but that's not important now.

The spreadsheet looks like this.  This is the "sorted by #" page, and gives you the sizing info in # order.

To begin with, the important piece of info is A, the root diameter.  This is the constant diameter section at the top of the needle, which controls the mixture (in conjunction with the pilot jet, mixture screw setting, slide cutaway and needle root diameter) in the first 1/4 to 1/3 of slide movement (depending on carb throat diameter, maybe even up to 1/2).  Consider, realistically, how often you use more than 1/3 throttle.  Unless you're getting up it for the rent, it's not as often as you might think (hope).

You can see that the K5 is 2.45mm root diameter, whereas the K18 and K20 are 2.50mm.  Meaning the result of running any of these needles will depend also on the chosen needle jet, which is why you might need a 268 with the K18/20 and a 265 with the K5 sort of thing.

And so the confusion sets in.

Comparing the combinations was the next part of the spreadsheet, with a page I called "flow area".  Now, the important part to remember here is that this "flow area" is a calculated number with a somewhat limited grip on reality.  Reality means that there is a Boundary Layer, which refers to the fluid (be it liquid or gas) that is immediately next to a surface over which said fluid is passing.  At the surface, the fluid is actually not moving, and from there the speed of the fluid increases as you move away from the surface.

In this instance of a needle in a needle jet, there are two surfaces and the important dimension that will come up later (maybe I should do it now) is the circumference of the boundary.  A needle with 2.50mm diameter has a circumference of 7.85mm, and the needle jet with 2.68mm hole has a circumference of 8.42mm, giving us a total boundary layer surface width of 16.27mm which the fuel is flowing over.

Compare this to the 152 main jet, who's circumference is 4.77mm and you can see that the needle/needle jet combo has 3.4 times the surface width of the main jet.  Why is this important?  Well, in the comparison and calculations to come, you can calculate the flow area of the main jet and from that deduce when the main metering device (ie, biggest restriction) moves from needle in needle jet to main jet.  Except that the boundary layer will impact here to some extent, and comparing the two jet systems has to allow for the impact of the boundary layer of the needle/needle jet system causing a greater restriction and thereby, in reality, giving a smaller comparative calculated flow area as compared to the main jet.  ie, the needle in needle jet will remain the main metering device to a higher throttle opening (slide lift) than the numbers suggest.

So, to be clear, this is a number of some use, to be used with some notion of the fact that it's not totally realistic, in the quest for some ability to compare needle and needle jet combinations.  

Compounding this is the fact that the K5 has 3 clip grooves and the K18 and K20 4 means the grooves are in different positions and therefore the relative position of the needles can vary there also.  With the K5 needle and clip fitted to the second groove, there was 56.5mm of needle protruding below the slide, and 50mm of needle inside the needle jet.  With a 40mm carb, and realistically 39mm or a bit more of travel from idle to WOT, this meant that the needle taper would become active around 1/3 throttle opening, and anything under that throttle opening would be controlled by (in order from closed throttle) mixture screw, pilot jet, slide cutaway and needle root diameter/needle jet diameter.  Next time you're out on your Sport 1100 carby mark the throttle and take a glance to see how much you're using.  1/3 throttle is fair acceleration at any speed under quite a bit too fast for licence.

The following piece of the spreadsheet shows the needle diameters, calculated flow area and % comparison between the jetting set up.  Original is the Moto Guzzi spec - K18 with 266 needle jet.  1 is the "as delivered to me": K20 and 268.  2 is my starting point: K5 and 265.  3 is my first revision: K5 and 266.  4 is my finishing point: K5 lowered 1 groove to the first and 266.

The highlighted areas are the approximate effective range of operation that will be used on the PHM40.  The green area is the "non main jet" section and the yellow the "main jet" section.  Apply the aforementioned disclaimers from above as required.  I'd say the needle/needle jet to main jet transition is around 2/3 throttle.

You can see how much richer than std the K20 and 268 is, and the spark plugs did reflect this.  The bottom line of the % comparison is the one of importance though, as that's where I ended up, and it shows how much richer then leaner my final setting of K5@1 and 266 was.

The spec for my first step was the previously fitted 60/3 slides, K5 needle with the clip in the second groove (K5@2), 265AB needle jet, 152 main jet and 60 pilot.  The airbox had previously been removed and replaced with these pod filters that I generally don't like.  There's no rounded transition internally into the inlet, and I don't think they flow that well either.

On the road for the first ride, it was quite flat at very low throttle and rpm - there was a real dead spot around 2,000 rpm.  It really came good around 2,800 rpm and up into 3 - 3,500 rpm.  On a moving with/through traffic roll on it felt a touch flat again, but rather nice anyway.  Based on those two feelings, and the fact that having marked the twist grip showed that nearly any riding within any confines of traffic had the throttle less than 1/4 open, I went for the needle jet as the first change.  This is the opposite of what I usually do to a 900 Ducati - SS, MHR - with PHM40, where going from a 265 to 264 needle jet cleans them up very nicely on cruise.  I was after a similar minor change here, just the other way.

Ride two with K5@2 and 266 was nice.  The roll on from 70 km/h (probably less than 1/8 throttle) with 1/4 - 1/3 throttle opening was lovely, and the very low speed pick up was better.  Still fairly awful to ride under 2,800 rpm though, compounded by the clunky box and gearing.  Then I went up from 60 to 62 on the pilot, which richened the bottom without making any real difference to how it ran under 2,800 rpm.  It's a very odd feeling - if you hold the throttle constant and let it accelerate in first gear from 2,000 rpm up, the change in drive around 2,800 makes me think there's a spark advance influence here also.  I don't believe it's just mixture.  Going back to 57 pilots confirmed this - there was a bit of flatness around 2,500 rpm when cold, but once warm was no better or worse that with 60 or 62.  ie, still crap.  Idle mixture screw settings for around 5.5% CO were 57: 3, 60: 2 7/8 and 62: 2 5/8 turns out.

With the 152 mains fitted, the jetting I was running, with open pipes and pod filters, was the same as it was when the bike left the factory with the exception of the K5 needle.

Next was the trip to the dyno, to get some hard numbers and try out some inlet ideas.  We ran it as it was, then removed the pods, tried some other little filters that I didn't think would be any different (they weren't), then fitted the ram tubes and Uni filters.  After the WOT tests were done, we ran 1/8, 1/4, 3/8, 1/2, 5/8 and 3/4 throttle runs to check the mixture.

First up, pod filters versus no filters.  Not sure what the dip around 7,500 is about.  I'm don't know how much raising the float levels from 21 to 18mm would have changed the mixture, but I had also already gone down 10 numbers on the main jets (162 to 152) before I went to the dyno, and it was still running 12:1 or fatter.  Getting rid of the filters certainly helped.  The leanness at the start of the run happened for all runs over 1/4 throttle pretty much, but you know and ignore that.

(digression) One thing that did come to mind here is the shape of the air/fuel curve.  Years ago I dynod a Magni, which had an over 1000cc LM4/5 engine (no idea specifically) fitted with PHM40 carbs and it had an air/fuel curve that tapered from lean to rich and made jetting a bit of a mess.  With the 175 mains it came in with it would kill the engine if you held it open from 4,000 rpm - at 6,500 to 7,000 it would shut down, then come back.  I figured it might be momentarily fouling the plugs.  Dyno showed OMG rich - off the scale (under 10:1) by 3,500 rpm.  148 mains fixed it, but the mixture tapered in a straight line from 14:1 around 3,500 rpm to 12:1 by 7,500 rpm.  My suspicion was air bleed sizing, which is not a variable in Dellortos.  So I was worried that we might see a similar thing here, but also curious that the fact these carbs were made to suit this engine size and rpm range may mean they were different internally to whatever variant of PHM40 was on the Magni.  Which is the inevitable incidence of "what you don't know you don't know" raising its oh so welcome head.

But the air/fuel curve is somewhat similar to what I see with the Ducati 900 motors and FCR41 carbs - a lean rise in the midrange and somewhat richer either side.  The FCR39 are better (flatter curve) in that application for a 900, but gave a similar shape curve on my 750.  Just another aside.

Anyway, back on track we go.  Pod filters in red, no filters in blue, 152 main jet on both.

Next the trumpets went on without filters.  My hope was that they would help, which they did.  The dip in the curve around 4,500 has moved down a couple of hundred rpm with the extra length, but it's still there.  My Sport 1100i had a similar dip, and the easiest common element to apportion blame to there is the camshaft.  Not that it's a bad cam.  I believe it actually came from Crane.

No filters or ram tubes in red, ram tubes without filters in blue.

The only decent air filter option I had found for the ram tubes as was were the Uni Filter socks.  I did think that you could weld a flat strip to the ram tubes on the leading edge of the bell for a large K&N or the like to clamp to, but in the interests of not spending any more money than needed on parts that may not be used we went this way.  Happily, they worked.  No filters red, filters blue.

This gave us a WOT before/after result as below.  Rather relieving and satisfying, as it turns out.  The mixture leaned off to around 13.5 at 6,000 rpm, so after I got back to the factory I went up from 152 to 155 on the main, which I think helped a little with the roll on at 3,000 rpm too.  Realistically, you don't ride these things by nailing it full open at 3,000 rpm, but it's nice to know it will do it and just pull.

The air/fuel traces from the part throttle runs mostly showed the same consistency in curve shape to the WOT runs, which again must be due to camshaft and maybe exhaust design.  We didn't record a run under 1/8 throttle, but with it bumbling along on the dyno at 2,500 or so rpm it was even richer, under 12:1.  This was with 62 pilots, and both Dave and I were sceptical of how much impact a one or two step leaner pilot would have.  But, as is the case with carbs, you only have so many ways to fix an issue, so later I went to 57 and, as it was no worse, left it there.  Low speed and throttle like this is controlled by pilot jet, mixture screw setting, slide cutaway and needle root diameter.  Fixing it can either be a lucky guess and succeed, or many hours of trial and error.

The richness of the over 1/4 throttle runs was the reason for dropping the needles from the second to the first groove.  I did that and the main and pilot jet changes after leaving the dyno (a dyno session without being covered in petrol, oh the joy), so don't have any confirmation on effects of the changes.  But it felt better on the road.

Red is 1/8, blue 1/4, green 3/8, orange 1/2, dark blue 5/8 and brown 3/4.  Olive is WOT as a comparison.  The fact that any more than 1/2 throttle below 4,500 rpm gets you no more power is something I didn't notice beforehand, and now I'm curious if there's anything more than a change in engine noise with more throttle in that rpm range.  Dyno says no, but then it is just a dyno.

The final ram tube and Uni Filter sock fitment came out as below.  I cut the LH filter and spring down by 30mm to allow for the cylinder offset and to have them both ending at about the same point over the frame cross tube.  I used 33-57mm clamps to hold the ram tubes to the carbs (I actually had to open the ram tubes up a little with a flap wheel to get them on the carbs, but you need to be sure they're not going to bail once out and about) and 52-76mm clamps on the socks.  Given the trumpets are tapered where those clamps fit, and clamping oiled foam is like catching an eel (as good a reason as any to quote the great Mojo Nixon: "I'm slicker than two eels f***ing in a bucket of snot"), so who knows how well that'll work out long term.  Undoubtedly I will be informed.

The filters come with a zip tie to hold them on, but it's a bit low rent for an external fitment.

The final result is nice above 2,800 rpm, but it's a fairly unpleasant bike to ride under that (which in second gear is 50km/h) and exaggerated by the clunky gearbox.  This was made very obvious when I road tested a 1000S after servicing at the same time.  The 1000S, which has similar PHM40 carbs and different, but similarly large camshaft, was a joy at low speed.  It'd pull away from almost idle happily, and from memory it was running mostly std jetting (K19@3 and 268AB) with not too loud mufflers and maybe similar little mesh pods.

This prompted me to look at a couple of things, namely ignition system and gearing.  

The 1000S had an original distributor and Dyna controller.  As a side note (another one), when I first saw this 1000S for a big service some years ago, I checked the ignition timing and it had 20 or so degrees advance across the range.  A locked distributor from a previously fitted electronic ignition (before this owner's tenure) like a Lucas Rita maybe, which didn't require the centrifugal like the Dyna does, as the Dyna simply replaces the points system to trigger to coils.  Parts for these distributors are so hard to find it was easiest to buy a complete s/h distributor.  A set of LM4 advance springs and away it went.  Wasn't as responsive down low as before due to the lack of advance under 2,000 rpm or so, but better above it.  I thought it was pretty funny, I guess someone figured 20 degrees was enough to make it work.

Anyway, it ran so much better at low speed than the Sport 1100, with more rpm at any road speed, that I thought I'd check the gearing.  Turns out everything is different - primary drive, gearbox and rear drive - as below.

So the Sport 1100 gear ratios are all higher and closer together, the final drive ratio is taller, but the primary drive ratio is shorter.  Overall ratios are still quite a bit taller though.  I know the gearing came from the Daytona, which was theoretically geared for 270 km/h at 9,000 rpm, and the racing bikes would have gone that fast.  But I still don't see the need for the road bike to have such a close ratio box.

The Daytona and Sport 1100 don't have a cush drive in the rear wheel either, so it can be quite abrupt on the on/off and the low speed baggyness only exaggerates that.

To get an idea of what can be done final drive wise, see below.  I rang Mario at Thunderbikes to see what diff ratios could be swapped in, and Mario mentioned an 8/35 gearset from a V7 Sport (I think).  From 8/33 to 8/35 is about 6% change, whereas 8/33 to 7/33 is 12.5%.  6% sounds pretty good.  I had also thought of swapping in a 17" rear wheel from the later bikes - Daytona RS, Sport 1100i, Centauro and the V11 series all use the same wheels, 3 spoke 17" with the same disc mountings and a cush drive in the rear.  Comparing the tyre sizes on a few manufacturers web sites didn't show a great deal of difference in the tyre diameters - 650mm for a 160/60ZR18 and 630mm for a 160/60ZR17 - about 3%.  As the Sport 1100 and Daytona wheels are a different spoke pattern (which looks better imo), you'd need front and rear wheels to keep it matched.

Looking back at my Sport 1100i, I don't recall the gearing being something that I really thought about.  But the low speed manners were much better.

The table below is calculated speeds at 8,000 rpm for each gear.  This bike has had the fairing removed, so as a naked I don't think 240 km/h will be required.  With the power peaking around 7,000 rpm, I don't know if it'd pull 8,000 rpm in top gear anyway.

Changing the final drive ratio, keeping in mind this is a 70,000 km old rear drive, will no doubt involve a rebuild, so as a job you'd be allowing $2,000.  Going to a set of 17" wheels, with a new rear tyre, would probably end up somewhere near that too.  Not a cheap gearing change.  And I'd probably want a wider spread gear set in the gearbox too, just to make it nice.

The next point of thought is the ignition system.  The Sport 1100 got the Marelli Digiplex system, which was also fitted to the late carb model California and Nevada as well as the Ducati 906 and 1990 900SS.  The Ducati workshop manuals give advance curves, but the Guzzi manuals don't.  To me, it feels like this system has a rapidly increasing advance curve coming up to 3,000 rpm, as the character of the engine just changes in a few hundred rpm.  I did put some marks on the ring gear teeth so I could give it a rough check, and it didn't seem too bad, but maybe it just wants more.

More advance can make a real difference, especially to low speed response and smoothness.  I tend to add quite a bit to lots of the spark advance maps when I'm playing with the fuel injected bikes just because.

It is possible to replace the Digiplex with an Ignitech to give control over the advance curve, but another concern, based on what we've seen with the Breva 1100 and 1200 models, is that more advance around 2,000 rpm or so can make them hold up on the return to idle.  So maybe they found that issue back in the day with the Sport 1100.  Fitting an Ignitech and setting it up, especially if you add a MAP sensor to allow extra part throttle advance via a 3D map, would run to at least $800 I'd think.  So more possible fixes, but none of them cheap or guaranteed.

Wednesday, May 17, 2017

Dellorto PHF PHM pump ramp profiles

I have a Guzzi Sport 1100 in to attempt to tune, and in going through what had been changed and what effects those changes may have had, I found some specs for the pump ramps on the PHF and PHM slides.  So, the obvious thing to do was make a graph comparing them all.  It makes much more sense in a visual form for me.

The starting point is nominally the idle setting, but that's not a fixed thing so the actual "when stuff happens" numbers are a bit ish.

The slides are numbered with an XX/Y system, where the XX is the cutaway (in tenths of mm) and the Y is the pump ramp ID (it's just a number).  The cutaways I've seen are 50, 60 or 70, and the slides are /1 to /5.

The cutaway affects low slide lift mixture.  The smaller number has less of a cutaway at the rear edge of the slide, which increases the manifold vacuum transferred to the top of the needle jet (atomiser) and enrichens the mixture due to the greater pressure differential between the top of the needle jet and the fuel in the float bowl.

The maximum pump lever deflection on an old slide I had measured at 5.6mm, so that's the maximum number I used.  The slide travel from closed to wide open is about 1mm less that the carb bore diameter, as at idle the opening under the front of the slide is about 1mm.  Ish.

The Sport 1100 had a /5 std, this one has /3.  Don't know if that's a good or bad thing.  Lots of the 41mm Malossi converted PHM 40 don't have pumps at all, and they're a "racing" carb.  And a trick when you're dyno tuning Dellortos is to pull the pump lever so you don't get any pump shot influence in your readings.  So you can do without them if you're not slamming the throttle open in an aggressive fashion (ie, doing roll on wheelies).  Where on earth is the fun in that you may well ask.  I would.

As an aside of some relevance, I'll add this from the Moto Guzzi Lemans 1000 manual.  It's just so delightfully delusional, and always makes me smile.

Dream on, my man, dream on.

Sunday, March 5, 2017

More Minnie the 400 Monster dyno runs

I took Minnie to the dyno today to see how the 2-1 works.  Not well as it happens - red is the 2-1 curve, blue the previous session with the std headers and Megacycle mufflers.

Pretty much dyno'd how it feels on the road - goes well under 8, no point going over.  I was going to set up one of the previously dyno'd Megacycle muflers to give just the change due to the 2-1 header, but didn't get to it.  I hadn’t revved it hard before the 2-1 went on.  Now that I have a tacho fitted to know how hard I am revving it, I can see that it would have been very unlikely that I was going over 8 anyway.  As such, I really didn't notice the now crap (ish) top end in comparison to the previous set up.  Maybe I need to make a twin muffler mounting bracket for under the tail and cut down the second Danmoto muffler to fit with original header.

I don't have any air/fuel for the original exhaust and Megacycle mufflers, as the bike killed the dyno on those trips.  The rpm and air/fuel were shutting down when we tried to run it.  After the last session I fitted resistor spark plugs, which you need to run with the Ignitech and which all these carby SS bikes (should have) had oem.  I assume that’s what made the dyno control happy.

First runs were baffle in and then baffle out.  I modified one of the Danmoto baffles I had.  It has 12 holes around it, and the total area of the holes was about the same as the muffler internal diameter anyway.  I machined the end cap of the muffler just a little to allow the baffle to slide in, and them machined a circlip groove to hold it in.  Of course, I didn’t have any circlips big enough to start with, so I bent up a round clip from coat hanger wire.  Gotta love coat hanger wire.  As below – without, machining, and with.

Made so little difference you’d have to call it none.  Then I found that the Showa fork spring preload tubes are a perfect fit over the Danmoto baffle, so I slid a tube over, tacked it on then cut off the original end cap.  The internal diameter of the baffle exit is now probably a bit under 20mm.  Again, not a lot of difference, but I ran with it. 

You can hear the slight change in these clips I took in the dyno room.  Not great sound, but definitely quieter with baffle from the bottom.

As expected, it hurt the bottom end a little.  Not as much as I’d hurt the top end though.  Baffling the mufflers usually effects the peak torque more than the peak power, but in this instance that’s a bit hard to see.

It was a bit (fair bit) on the rich side, so I thought I'd try it out without the airbox lid.

It was a bit better power wise, but the mixture change was pretty extreme.  More than I think I've seen before on a 2v motor.  Too rich to more too lean.

Then I tried it with lid, but without the snorkels.  That helped a bit, but still too lean on the needle.

I have some of the original 400ss carb springs, that are a lot lighter than every other OEM Mikuni spring I’ve seen them fitted with.  I might try them, not sure if that'll make it better due to the increased slide opening lifting the needle more, or worse because it'll have less vacuum over the jet and the needles aren't tapered enough anyway.  I do have some jet kit needles that might be the go.  Probably with springs as well - you’d just call that fitting a jet kit.
I rode it back from the dyno with one snorkel fitted and without the baffle.  It felt a bit stronger without it, but the missing snorkel may also have been helping there.

The Ignitech unit I fitted before this dyno session has the same advance as the std boxes.  Well (you know when you make assumptions and then later you think "oh"), maybe I should check that - it should have the same advance.  
I know that from the previous 750 engine testing that lack of advance hurts the top end and can give an exaggerated choppiness to the curve.

This early Ignitech TCIP4 has a delay that increases as rpm climbs.  The newer units (this one I've had since 2005 or so) don't.  I thought I had allowed for it in my curve, but maybe not enough.  I did have the oem boxes with me at the dyno, but my time was pretty much up there and I had to get back to work anyway so I didn't.  One thing I hate about not having my own dyno running is not being able to act on all the things you think of later when it's too late.

So maybe it didn't have enough top end advance, and it was rich anyway.  
Fairly extreme fuelling (well, air entry affecting fuelling) changes didn't make a big difference either, although it did go from too rich to too lean.  The last run I did had the mixture back at 13.5 or so in the crap top end area, so that pretty much rules mixture out.

Although I ran these same carbs years ago when it was a std 600, and I would have thought with a smaller engine it should be leaner due to less suck.  For some of the production years the M400 and M600 are fitted with the same carb spec (same part number).  I did shoot some video through the airbox lid without an air filter fitted of the slide, and it did look like it was lifting all the way up.  I was wondering if it would, given it's a pretty big carb for a 400.  Lots of fuel flying around too.

Through the snorkel hole

As it sits at work now (waiting for a nice day and time to go for a ride, it's pretty hot here now) it has one of the Megacycle mufflers fitted to rule that change out, and I'll put some oem ignition units in my pocket and fit them on the road. I really can't see the exhaust alone hurting it this much, as nothing I've done exhaust wise in the past has, but I'm often wrong.  And I do have concerns that the 2-1 merge isn't deep enough into the V of the original connector.  It may actually allow flow from one cylinder to go back up the pipe toward the other cylinder. Not so bad from the vertical as the pipe in is angled, but from the horizontal it can.  That's possibly an issue and not one I can do a lot about with this header set, especially now they’re ceramic coated.

Tuesday, February 14, 2017

Some more Gates belt stuff

One of the things that surprises me when I write posts are the reactions I sometimes get, specifically the questions that often leave me wondering how people interpret or comprehend what I've written.  It makes me realise how hard it can be to be clear and get what I'm trying to say across.  Compounded by my tendency to ramble and digress and straight up forget what I was rabbiting on about in the first place.  So I'll put in some more belt info, and try to respond to some of the comments and questions.

Another thing is that (especially with cam timing) people ask me for "the good numbers", as if there's some sort of secret squirrel component to what I write.  There's not.  What you see is what you get.

Anyway, belts.

The old Gates belts were available for all the Ducati models pre 98 external to Ducati via Gates distributors.  The three part numbers were "cancelled" in Australia last year, not sure about the rest of the world.  They were all differing construction types, which I found a bit interesting.

T934: the 900 round tooth belt - 900SS, M900, 906, 907, ST2.  1st generation construction, NEO - Neoprene rubber fibreglass tensile cords and nylon tooth facing.  Interesting that the belt introduced last was the most basic construction.  Never gave any issues.

T819: the Pantah square tooth belt - all small blocks (non 900) up to 1997.  2nd generation construction, HTN - High temperature neoprene rubber, fibreglass cords and nylon tooth facing.  Never gave any issues.  When the Pantah was first released, they had Pirelli belts which were rubbish I'm told by people who worked on them.  And gone before my time.  I have also seen Continental belts fitted to these motors.

T917: the 4V belt, also fitted to Renault R19, which ran from 89 - 96 according to the Gates book.  3rd generation construction, HSN - Highly saturated nitrile rubber with aramid fibre loading, aramid or high tenacity fibreglass cords and nylon tooth facing.  The problem belt (from 98 onwards at least).  The interesting thing is the aramid part.  Aramid is a generic name for what is better known by name brands such as Nomex and Kevlar (both owned by DuPont).  So these belts it appears had a Kevlar component, which was allegedly the big point of the red letter belts.

So to clarify, the only Ducati belt made by Gates that gave any issue was the T917 - available via Ducati or Gates.  And the issues only appeared as a consistant problem in 1998, by which time Ducati seemed to have realised there was an issue as the "2 year replacement" directive was communicated to the importer (ours at least) before we had experienced it.

Why there was an issue I don't know.  Lots of theories were expounded, but I like facts backed up with evidence and there didn't seem to be enough of that to generate any conclusions.  Lots expired down the front straight at Philip Island, but lots didn't.  They just broke on bikes that were more than 2 years old, but had done less than 20,000km.  We also saw belts break that had been fitted at 20,000km services, but not replaced again within the 2 year window.  Yes, the pullies are quite small compared to most automotive applications.  And, on the 4V, there are quite extreme changes in direction compared to what you see in most automotive design.  But, anecdotal evidence of belt life before and after, especially with the later belts, would indicate that the actual engine design is not "the" issue. 

The Red Letter Belts, or whatever you wish to call them, were introduced in 1999 or so - I don't actually recall now.  The main claim to them was that they contained Kevlar.  All still made by Gates and marked as made in the UK, but not available outside of Ducati.  Some were a bit more expensive, the Testastretta belts a lot so.

Whether or not all the red letter belts actually contain Kevlar, I have no idea.  If you can find someone at Gates who does know, pass it on.

As to the two year replacement interval thing: Firstly, I have no interest in arguing this in the slightest.  Absolutely none.  Believe it.  Don't believe it.  I don't give a rat's arse.  But every official Ducati workshop manual from 2000 until the MTS1200 has had the two year replacement regardless of km specified.  At the bottom of the scheduled maintenance chart or on the next page, it will have the note corresponding to the (*) or (1) after the Timing belt line saying "Replace every two years, in any case."  With the MTS1200 and Diavel it became 5 years.  As I'm not part of the dealer network, I didn't get the official explanation as to why.

As to how often I change my belts: I have only had one belt drive bike in use long enough to require belt changes, but then again it's also on its third engine in its time with me and there's been a bit of idle time.  I think only the 750 engine has had belts in it long enough to need them to be replaced, and I only did that when I realised (after noticing the dates on dyno runs) they were over 5 years old.  I'd guess the belts in the 851 are getting on for 15 years old now, but it hasn't run in 12 years so that's no big deal.  Everything else has been moved on before time.  But I'm a tight arse too, so any belts in my bikes will be in there for as long as I can withstand the niggling paranoia of impending doom.

I've not used any of the Dayco belts.  As the Australian distributor for California Cycleworks products, I use the Exactfit belts as the aftermarket option.

Saturday, February 11, 2017

I've gone bigger font. Someone's eyes aren't what they used to be.

Ducati timing belt failures and replacement intervals

I thought I’d do a piece about belts as there’s a thread going on MS at the moment with responses from people who weren’t there when the shit went down and so don’t understand why.  I’ll try to clarify it from where I saw it.

The first reference to replacing timing belts based on time as well as km that I can find in any of the scheduled maintenance charts in the factory workshop manuals is 1999 996.  For the 1999 MY I also have ST4, M900 and 750SSie manuals, and none of those have it.  All the 2000 MY manuals have an * after “Timing Belt” on the chart and “(*) Replace every two years, in any case” at the bottom of the chart.

As to whether there was a service bulletin about the two year thing, I don’t know.  I have quite a lot of Ducati service bulletins, some back to 1990 or so, but nothing on belt change interval, nor a listing for it in the index.

The first broken belt I saw was in 1995 or so, a 900SS that came in for an opinion to be used in a court case against another dealership.  Typically of the very few 900 that I have seen with broken belts, it also had a loose vertical cam pulley.  As in flogged out and flopping around.  It went again without us touching it.

I think I saw one Pantah with a broken belt.  Asking the owner when they were last changed just drew a blank look.  It got a new belt and was fine, one of the few.

I recall Rob doing a head that was bought in, probably in late 1997 or so as I recall it being in the then new engine room, from an 888 that had broken a belt.  Didn’t know anything else about it though.

The first broken belt we were really involved with was a 916 owned by a friend of Rob’s.  Sold mid 1996, with the 10,000km service done mid 1998 around two years old.  It broke a belt a few months later at a Moto One Broadford track day.  We got it back to work on the Monday after, pulled it apart and found the horizontal (almost always the horizontal) belt broken.  You can tell if the valves are bent by trying to rotate the cams.  If the valves are bent, they pull the closing rockers down and jam them against the cams, thereby stopping them.  Simple check.  I recall one 916 coming in that we fitted new belts too and away it went.  Only one that lucky.

We rang the importers and got asked “why weren’t the belts changed at two years old” and we asked “why do they need to be”.  Then the typical “well, it’s all your fault because .....” that we heard quite a few times from importers over the years.  I don’t recall ever hearing anything about two years before that day, nor seeing anything from Ducati (service bulletin, etc) saying it, but the message from the importer was very clear.  Two years, no more, no help because the warranty’s up.

That was the start of it.  Probably averaged a couple a month for the next year at least.  748 and 916, 10,000 – 15,000km, 2 ½ to 3 years old.  Owners would come in wailing and wanting warranty, us explaining the Ducati line and the fact it’s out of warranty, us getting abused because somehow the mechanics at a dealership half way around the word from the factory are responsible for any design shortcomings.  All that stuff.  We were the preferred warranty dealership in Melbourne it seemed.  When the warranty claim rejections were faxed back and the owners informed, the bikes got picked up and went elsewhere to be fixed because we were too expensive, arseholes, etc.

Of course, while the message from the importer was simple, their own dealership compounded the issue.  We harassed every owner who came in with a bike from then on to replace the belts at two years old.  Everyone.  But we had customers who would ring up Fraser Motorcycles in Sydney and ask their workshop and they’d get told “we just look at them, and if they look ok, we put them back in”.  Then they’d come back in to us and tell us again we were arseholes trying to rip them off, etc.  The usual, with a new slant.

So we started putting “Timing belts not replaced at owner’s direction” on invoices.  Owners would see that (we’d usually point it out to them) and realise we were serious and if it did go bad it was their problem.  Then they’d get the shits because we didn’t tell them enough to convince them that they really did need to be replaced.

I can recall still getting phone calls into 2001 or so from owners at Philip Island track days.   One guy, who I knew we hadn’t seen since his first service in 1996 or so, had his 916 drop a cylinder down the front straight.  Turns out his bike had only done around 6,000km and probably hadn’t been serviced since the first service because there was no annual service regime back when it was new.  I gave him the usual advice: remove the belt covers and check the belts, the horizontal one is probably broken.  Unfortunately correct.

I saw one 851SP3 do it, and again it was a case of the owner being told, when he bought the bike second hand in 1996, that it was good to go until 20,000km.  I think I saw one 916SPS break a belt, I’m sure I had a 1998 model apart for that reason (no Ti rods!) and one 916 that did it within the warranty and belt life period, but there were some other potential concerns about that bike anyway.

I don’t recall a 996 doing it, and I think that’s because the new “red writing” belts with Kevlar in them were introduced with or around the time of the 996 in 1999.  I forget now.  And we were harassing everyone to replace belts at two years, so none of the bikes we serviced would have gone much past two years anyway.

In hindsight, the whole thing was handled poorly from an administrative sense.  BMW (who we were also dealers for, and who had time based service schedules) would’ve sent letters to all the owners pointing out the two year deal.  Of course, a lot of them would’ve been ignored until the bang came, but at least they had been warned.

The belt that caused all the issues was the Gates T917, which was originally a Renault belt.  Why it all started going bad in 1998 I don’t know.  Maybe it was the simple increase in sample size, with a lot more 4V bike sales, coupled with the increase in track day participation.  Nothing else changed in terms of engine design or layout.  Once that belt was out of the official spare parts system, the problem was effectively fixed.  You could still buy them via Gates, as we did for the Pantah and 900 belts, but we mainly kept away from the T917.  All the Gates parts numbers for Ducati timing belts were cancelled last year (in Australia at least), so now they’re gone for good.

There wasn’t an issue with 2 valve bikes simply due to a bit too old belts.  Very old belts yes, but not like the 4V.  I have had my own 2V bikes go 5+ years simply due to forgetfulness while still in use.  Nor is there an issue with the later models.  I have seen the occasional broken belt since.  I had a 1098 come in that had nothing but fluff on the horizontal and strands with teeth on the vertical, but it had at least one seized roller and I suspect hadn’t had a belt change in its 52,000km life.  The damage on that one was quite amazing.  The valves were Z’d (bent above and below the guides), and I couldn’t get one of the inlets out.  The inlet cam had flats on the noses so beautifully precise it looked like it’d been held in a fixture and stamped with a machine, with the material flared out both sides evenly.  The piston was also damaged, with a crack through the skirt into the pin boss.  Probably the first time I’ve had to do anything with a piston when fixing valves bent due to a broken belt.

But, due to professional paranoia and liability, we hassled everyone to replace belts every two years on all models, as Ducati directed.

Now they have moved the replacement interval out to 5 years on new models.  The MTS1200 and Diavel use the same belt as the 1198, etc.  Maybe, in the main, the SBK models get used a bit harder than the tourers rpm wise, but some of the MTS1200 get used pretty hard and often.

My question about that was, given the warranty is two years, what happens if a belt fails outside the warranty, but within the service time frame.  The answer to that, in the current Audi ownership model, is simply that someone other than Ducati will be paying for it.

I recommend 4 years at least with the genuine and California Cycleworks belts.  I don’t go over the mileage intervals, but again they’re being stretched as time goes on too.  What was only 20,000km became 24,000km and is now 30,000km, with no checks or re-tensions in between.  We used to re-tension belts every service, now you don’t look at them until the replacement time.  And with the massive increase in the amount of time required to just access the belts on some models – MTS1200, Diavel, even the M696 – 1100 series, it’s not easy to have a quick look.

Nowadays lots of owners who didn’t experience any of the belt drama back in the day question the two year thing, and many like to claim it’s a money making exercise, etc.  But the basis for it was a real problem for some models, and cost many people quite a bit more than the price of a set of belts.

Sunday, November 27, 2016

More Minnie Monster photos with her custom look.

I took some photos of her in front of the factory.  I'm really liking the look.  Still haven't fitted a dash - the Acewell 6554 has arrived, but with no pressing need to get it fitted, she's once again back to waiting for the dreaded time.