Saturday, October 27, 2012

Festival Of Italian Motorcycles 2012


This years FOIM is on Sunday November 18 at a new location.  Actually an old location, the Argyle Gardens on Lygon St, Carlton.  I attended the FOIM there a couple of times in the mid 90's, one year riding Trev's Guzzi V7 Special (actually an 850GT masquarading as a V7 from memory, before I had finished my own).

It's a great location, right in the middle of Lygon Street.

I'll be there under my little fold out pergola talking for 4 or so hours and seeing not much apart from the passing faces.

Friday, October 26, 2012

New Bike!

Well, I say it like I'm all excited.  I've actually had it for two weeks and haven't really done anything to it, apart from wonder why I thought it was a good idea.

I have spent some time on Ebay buying bits though.  Maybe that's where the enthusiasm has gone.  Sucked away like the money from my Paypal account buying another fuel tank to replace the prevously repaired and still weeping original one that has an interior full of nasty.  And a standard muffler.  When, oh when are people going to realise that standard parts are worth keeping.

Realistically, had the fuel tank repair and condition been listed in the Ebay ad I'd probably have steered clear in the first place.  As ever, there's always a reason why things are cheap.  At least the frame's not cracked.

Which reminds me, I haven't said what it is yet.  An SS.  All 400 badass, ball tearing cc of it.  A 1993 model, it's actually one of a few genuine Australian import SS Juniors.  With 85,000km on the clock it's done its share of work, but hopefully it'll stand up to some riding, and no doubt some dyno runs.

1993 means gold frame and black wheels (unless it's a 900SL or 888SP5, of which it is definitely neither).  I dislike black wheels with some passion, especially on 1993 model Ducatis.  The 1994 bikes with the gold wheels just look so much better to me.

Unfortunately, 1993 also means 17mm front axle.  I was thinking I could just pull the wheels and slot them into Minne, who as a 1997 model has gold wheels.  But as a 1997 model she also has a 20mm front axle, and the two are completely incompatible.  And swapping the speedo drive with the front wheel won't help either (forks are the same axle hole wise) as the SS and Monster speedos require different drive ratios.

As to intent, well, permission for the purchase was provided on the notion that I could turn it over and make some money.  Which, if history is any guide, is something I am simply not capable of when it comes to motorcycles.  My thoughts have turned to maybe selling Minnie instead, although to do that and have it be worthwhile Minnie needs to be LAMS again, which means fitting a 600cc engine.

Or an engine inside some 600 cases, using the 750 crank currently inside the engine in her, 620 pistons, 750 heads machined to fit, etc.  As if i have time to do that.  And it's not exactly in the spirit of the LAMS law either.

Of course that leaves the left overs and other parts on hand to make an 827cc small block.

A photo of it about to come off the trailer.  Only one I've taken so far.  So my first 'new' bike in 8 or more years isn't really filling me with enthusiasm it seems.


Sunday, October 21, 2012

Throttle Position Sensor setting procedure for Moto Guzzi California and Bellagio

I had an email asking about Cali TPS set up, and I'd had this report almost ready to go for some time, so thought I'd pop it up here for a quick view.  It will go into the reports at some point of time as that way it's easier to find.

The throttle bodies fitted to the California and Bellagio are unique to these two models.  They are 40mm bore and have a link from a central cable wheel out to each throttle blade.  So the procedure has a couple of variations from the other Guzzi models.  Generally the throttle bodies on other models have a cable wheel on one throttle, then a link from that to the other in a master/slave style relationship.  With the Cali and Bellagio throttle bodies it’s more two slaves (call it a co-op for the socialists among us) so the idle balance is not influenced by the running balance at all.

The throttle body set up procedure is the same for both the early P8 ecu and later 1.5M ecu bikes.  The photos relate to the later 1.5M ecu bikes with the small round TPS.  P8 ecu bikes generally have the large square TPS, but the concept and procedure are the same.
The photos below have red numbers to denote components and then yellow numbers and arrows to denote them being used later.  Each number is only used once.
All instructions are based on the premise that you have the equipment required up to and including the diagnostic tools and gas analyser.  You may not, and this will influence how far you can go.  Ideally you will go all the way.  It’s always nicer.
1/ Remove the crappy plastic throttle body covers.  They can have little cap screws or 5.5mm (from memory) hex screws as circled in yellow.
2/ The TPS is mounted under the LH throttle body.  The photo below shows the air bleed (1) and TPS (2).  The TPS screws are 7mm hex on earlier bikes or Torx20 on the later ones.  Getting all the yellow sealing paint out to allow the torx fitting to seat correctly can be a pain.
3/ On top of the LH throttle body is the blade arm pivot point for the black plastic arm coming from the central cable wheel (3) and the throttle balance adjuster screw (4).
4/ The throttle stop screw for the LH throttle body (9) is at the rear, as shown below.
5/ The RH throttle body is much the same, just mirrored.  Throttle blade arm pivot point for the black plastic arm coming from the central cable wheel (6), throttle stop screw at the rear (5), air bleed underneath (8).

5/ The screw at the central cable wheel is the fast idle adjustment.  It has nothing to do with throttle balance.  Although, given the little lever at the clutch side of the bars generally won’t stay where you put it, it often has very little to do with the fast idle speed either.
6/ Back probe the TPS connector to take the voltage across the two outer wires.  You need to turn the ignition on to power the circuit.  In its original position, you should see 400 – 500mV and up to 4.85V at full throttle.  I note the setting just for the sake of knowing.  If you don’t get the required voltage from the two outer wires you may need to try other combinations, but I believe that is correct.
7/ To baseline the TPS, disconnect the black plastic arm coming from the central cable wheel (3) by removing the little C clip.  Be careful, as these little clips are incredibly good at pissing off on you.  And spending half an hour crawling around the floor to find a 20c part is incredibly annoying.  Then wind out the throttle stop screw (9) until the throttle blade can fully close.  I tend to snap it shut to make sure it can fully shut, but then open and close it more gently to not get a false reading.  Gently closed with a little force is the best way to get a good base setting.  Generally you’d expect to see anywhere from 100 to 180mV.  Again, I note the setting just for the sake of knowing.
8/ Loosen the two TPS screws and move the TPS as required to give 150mV.  I always check the voltage again once the screws are tight, as things tend to move around enough to often frustrate you.
9/ Once you have 150mV with the throttle fully closed, wind the throttle stop screw (9) in again until you get the desired voltage for idle.  The manuals give the reading in degrees of throttle opening, which you read via the diagnostic software.  The spec is 3.2 to 3.6 degrees.  Nominally, this corresponds to 486 to 528mV.  The relationship is mV = (degrees x 105) + 150.  Although, the ecu doesn’t always read this the same.  No idea why.  You might set the throttle stop screw to, say, 486mV, but via the diagnostics you’ll get 2.9 degrees instead of 3.2.  Or 3.5.  Just the way it is.  I usually go by degrees, not mV.
In the past I have found variation between bikes from some needing the stop set to 3.2 degrees or they’ll idle too high to some set to 3.6 degrees and air bleeds wound out to bring the idle up.
From here in, the LH stop screw is not touched again.  Unless you have a too high idle condition after step 13 or 16.  Then you have to adjust as required to make it work, unfortunately.
10/ Reconnect the black plastic arm coming from the central cable wheel (3) and refit the c clip (just as easy to lose now as it was when removing).  Check to make sure the throttle hasn’t been opened at all by this.  The voltage out of the TPS will tell you if it has.  If the TPS voltage does change you need to add slack to the opening throttle cable or back off the fast idle adjusting screw (7) as required.

11/ Hook up the balance equipment to each manifold and wind the air bleeds (1) and (8) fully in.  I note how far out they were just for the sake of knowing.
12/ Remove the plugs in the headers and fit tubes to sample the idle mixture.  Didn’t take a photo of them, sorry.  Generally a 15mm hex head.
13/ Start and run the engine until warm.  It should idle to some extent with both air bleeds fully in (chuga chuga chuga).  Because the idle balance is not influenced by the running balance at all, you adjust the idle balance by the RH throttle stop screw (5) so that you have equal vacuum on both cylinders.
14/ Now you adjust the running balance.  This is a compromise based on how much variation you get in cylinder to cylinder vacuum as you open the throttle and increase the rpm above idle.  Also remember that you might get to 8 or so degrees opening at most when free revving it in neutral up to 6,000rpm or so, whereas on the road you’ll often be above that just cruising.  So you’re not getting a full “through the range” indication – there’s no way you’ll get to even quarter throttle on a free rev.  I just look at the variation in vacuum between the cylinders and adjust the balance screw (4) as required to give a best overall compromise.  If this adjustment changes the idle speed then you need to add slack to the opening throttle cable or back off the fast idle adjusting screw (7) as required.
15/ Next step is to set the idle speed.  Hopefully it’s not too high, so you wind out the air bleeds (1) and (8) as required to get the speed you want.  At this point open them to maintain equal vacuum on each cylinder.  There tends to be a strong temptation amongst many owners to idle them low, but ideally you want 1100rpm.  Don’t believe the tacho either, they tend to be wrong in either direction.
16/ Last step is to set the idle mixture.  On the P8 bikes this is done via the trimmer on the ecu.

 The idle trimmer on them is the screw in a hole next to the large wiring loom connector often covered by a plastic cap. To access the trimmer you just dig the cap out.  See the photo below.
Of course, on the Cali with the P8, the trimmer is up under the pillion seat and although you can work the ecu down and out without pulling the pillion seat, it‘s as much of a pain in the arse as you’d expect.
The idle trimmer operates over a range of 4 turns, but it’s possible to turn past the end point in either direction endlessly without changing the trim pot output voltage. Duane Mitchell at Ultimap says you can set the trim pot to the default “central” position by turning the trim pot 5 turns clockwise and listening for a little click (it’s rather little). Then turn back 2 turns counter clockwise and this is the central position. You now have 2 turns in either direction for adjustment. I’m sure I’ve done it on my own bikes this way. Alternatively, you can remove the lid of the ECU (the top as it is fitted to the bike, mounting tabs to the bottom) and using a multimeter set the trimmer by its output voltage. See the diagram below for the location of the terminals to take the voltage from. This is the most accurate way to get the default “central” setting for those who like that sort of thing.
Just remember that you have 2 turns of adjustment in either direction – it may help to write down what you’ve done.
On the 1.5M ecu Cali (mounted behind the LH side cover) and the Bellagio with the 5.9M/5AM the trimmer is an electronic setting via the diagnostic tools.  Although, from 2003 onwards the Cali are closed loop, as is the Bellagio and generally there’s no idle mixture adjustment on these bikes.  The lambda sensor does that within its narrow band of adjustment.
Usually I aim for 4.5% CO idle mixture.  Given there is only one idle trimmer for both cylinders, I check the mixture and then adjust the trimmer to get the average between both cylinders where I want it. Then I adjust the air bleeds to give the same mixture in both headers. This means that the manifold vacuum balance or synchronisation at idle will often not be equal. That’s just how it is.  Equal mixture CO% is more important in my experience.
I do recall a P8 ecu Cali that would backfire if the mixture was leaner than 7%, so it is sometimes a compromise between theory and the practicality of best running or fuel economy, etc.  The above procedure assumes that at the end point the set up is as intended and the mapping is good and all will be well.  If the mapping is crap then it’s a bit of a crap shoot.
And if the idle is too high at this point with the air bleeds both wound fully in then you’re back to step 9 and 13, winding the throttle stop screws out as required to give the idle you need.

Saturday, October 6, 2012

Speedymoto Tallboys clip ons for early Monsters

I fitted some Speedymoto Tallboys clip ons as part of a crash repair to a 1997 Ducati Monster 600.  One of the issues with the pre 2002 Monsters and clip ons are the top triple clamp screws which sit at the outer front edge of the triple, exactly where most clip ons rise to the bar clamp. The 2002 on models have a rounded edge and the clamp screws is moved to the front and inside of the fork leg.  So for the pre 2002 you either have very low bars or lift the forks up so you can put the clip ons above the top triple.  Which makes the front even lower and reduces the rake.  Or replace the top triple, which starts to get (even more) expensive.

The Tallboys get around this by the placement and style of their risers.  As fitted to this bike, they are as low as possible and can come up another 32mm if slid up to the bottom of the top triple.  So they're not a huge amount lower than the original bars.  However on this bike the originals had been replaced with some higher steel bars, so they were definitely quite a lot lower.  They're also quite wide, which is the thing that really struck me when I first sat on the bike.

But when out riding it didn't feel too unusual compared to my otherwise identical M600.

The photos show them fitted at their lowest possible setting.

Danmoto Jisu muflers for older Monster

I finally got around to fitting the other Danmoto Jisu muffler to Minnie and gave them a run on the dyno.  The LH one sat out just enough from the swingarm, but although the RH could be fitted with a little clearance, by the time I got to the dyno it was rubbing.

I do like the way they look though.

Photos of the other side fitted some months ago here:

The sound was a little different to the Megacycles I think, but I can't really remember how.  I took some video in the dyno room of the two to see how they compared, and to watch for exiting packing from the Danmotos as others have said they do on a dyno run.  Danmoto actually include instructions about (not) dynoing their mufflers, in particuar the carbon ones.  But these ones are nice and strong so I couldn't see there being much of an issue.

I shot some video of the sound, although I'm not sure if my position in the room was good or not.  I figured being in front of the mufflers might have made the sound less harsh (for the crappy camera), but in reality I have no idea of what they actually sound like on the dyno due to the ear muffs I've always got on.  So I'm not sure if I can really hear a difference.  Danmotos first, then the ever trusty Megacycles.

As for power comparisons, the Danmotos were going in to this fight on a hiding to nothing, as the Megacycles are about the best performing mufflers I've ever come across.  Particularly bottom end. Which made the news Dave gave me about Ken shutting down Megacycle rather sad.  10 years ago Melbourne had 3 places to go for custom exhausts: Madaz, Megacycle and Moorabbin Motorcyce Engineering.  Now they're all gone.  I don't know of anyone else doing it now, but there's obviously people who'd do Harley stuff at least.

Red is Megacycle, blue Danmoto.  Not too much in it really.

It does also appear that the Megacycles, while making more power, are giving a richer mixture.  This is consistant with my theory that a better muffler downstream of a CV carb makes them run richer if the upstream inlet side is unchanged.  I'd like to do some runs with the mixture sampled out of the header ports for std and aftermarket muffers to get some hard data though before I go saying it too loud.

One other run I did was a no change run after letting the bike sit for 15 minutes.  I have often seen results that to me have more to do with the nature of dyno testing than changes made.  I have many sequences of runs where we'll do some WOT runs, then all the part throttle runs and finish with the same run as we started with.  Often the power will pick up 1 to 3Hp, even though there's no change in mixture.  I'm not sure if it's a tyre thing or a dyno room thing or just a hot engine that has soaked then cooled a bit.  Original run is in red, 15 minutes later is blue.  The change in mixture (leaner) surprises me, but apart from heat soak of the carbs I don't have an explanation for it.  I'm not sure of the impact of fuel temperature on power levels or mixture as delivered by a carburettor. 


Friday, October 5, 2012

Minnie gets some FCRs (aka, a day full of arrrgh)

So I bought a pair of FCR39 on ebay some time ago, and they've sat on a shelf ever since.  I found some time today to fit them and plough my way through the usual comedy of errors that arise whenever I'm trying to do something in a hurry.

I believe the carbs had come off a 750M, but the main jets were surprisingly big at 165 mains.  Otherwise they appeared to be as they are delivered, with the 60 pilots and EMT needles on the third notch.  I dropped the mains to my pair of ever accomodating 152 based on some advice from JD Hord along with 52 pilots, raised the needles to the 4th notch, set the idle mixture screws to 1 1/2 turns out and the slow air screws to 1 turn out.  I didn't bother checking the main air jets, and I would expect them to be the spec 200 as no one ever bothers changing them.  Although I do believe that Bruce Meyers recommends going bigger.  More on that below.

After a phone call to Tony (he of the short rubbers mod) I decided to route the throttle cables between the RHF indicator mounting block and dash mount over the headlight and down the LH side under the diagonal frame brace.  Which took the usual amount of routing and re-routing and induced crankiness.  "arrrrgh" moment #1.

I hogged out the airbox around the throttle cable mounting area and was proceding quite well until as I was about to refit the airbox I noticed fuel dripping from the inlet cross tube.  The second of my "arrrgh" moments, this required the replacement of the o-ring on the end of the tube.  Sounds easy enough, but this involves separating the carbs, meaning you have to undo the RH slide control from the throttle shaft to allow the RH carb to slide off the shaft.  No problemo there, but putting it back on involves refitting the balancing adjuster.  Frankly, I don't have any understanding of how this adjuster works.  It makes no sense at all to me.  I ended up using 2mm drill bits to set the slides theoretically evenly (or as close to is as the infuriating "moves as you tighten" system allows), but then set up some longer leads to allow me to run the engine with the airbox and battery out to check the balance.  As it happens, it was fine.  No idea why given the confusion, but there has to be a little gold in every bucket of poo to keep you going.

As an aside here, I did go looking for some info about this, and the best info you'll find for FCR tuning is Patrick Burn's FCR tuning guide:,Pat.html with now being a good time to mention it.  Read it and take note.

But I couldnt find it yesterday when I was fitting them up, which is a pity as I had the "synchronizing" (as the Americans like to call it) procedure totally wrong.  Getting it totally wrong leads to statements like "or as close to is as the infuriating "moves as you tighten" system allows", but I got there eventually.  As Patrick says, it does take 5 times as long as you expect.  And given the slide caps are covered by the airbox, you can't reassemble the bike then adjust without disassembly.  And that sucks.

Splitting the carbs also let me work out why the slides would jam at half open.  Seems the little wheels on the RH slide weren't pushed all the way on.  A good hard push to snap them back on and a quick clean and the jamming was gone.

I did forget to reattach the accelerator pump transfer hose from LH to RH carbs, but as it turned out that didn't influence the pumps (not) working.  Depending on the pump circuit design, if the circuit downstream of the pump isn't sealed the pump can't push and suck like it's meant to and nothing hapens.  The float bowl formed rubber gaskets had both been sitting incorrectly around the little pump circuit internal transfer passage, being pushed out into the float chamber.  I did manage to work them back into (soft of) shape and I assume they stayed where I wanted them when I jammed the float bowls back on.  But the pumps still didn't work and the ride to the dyno and dyno runs didn't improve things.  It's quite amazing how much they really don't need the pumps.  You can't snap the throttle open under 5,000 rpm, but it's not as bad as you might expect.  I plan to look at this issue in the future.  If it annoys me.  And I can be arsed.

But she started with the first try (an excellent prompter for putting the little things off) and seemed to run ok.  I did wind the idle mixture screws around to see what it liked, and as it turned out it idled happily with them fully in, so I need to put smaller pilot jets in.  Given it has 52 now and I think I only have down to 48 hopefully 48 will give me a rich/lean reaction to the screw adjustment.  It should also cure the just off closed throttle richness that I'm getting when cruising in 2nd at 40km/h sort of thing.  I did try adjusting the slow air screw setting from the original of 1 turn in to 3/4 then out to 1 1/2, but that appeared to not make any difference.  Especially one of the desirable kind.  I didn't do any dyno runs around 1/8 throttle due to some time contraints at the dyno, but did some 1/4, 1/2 and 3/4 ish runs as well as the WOT.

The 152 mins were too lean, and combined with the lack of pump shot made the roll on at the start of the run a flat spotter's paradise.  And I noticed some light pinging in the 5 to 6,000 rpm range, which I haven't heard before.

First graph shows the mixture for the WOT (blue), 3/4 (red) , 1/2 (green) and 1/4 (purple).

The 1/2 throttle run really shows the tapering mixture affect that I've seen a bit with these carbs (and Dellorto PHF too). This would be helped with a larger main air jet and then chainging all the other jetting as required, but that's more jets to buy and a whole new day of tuning. The 1/4 throttle is a lovely flat line around 14.7:1 (could be a tad richer), and the tuning diagram shows 1/4 throttle as being needle root diameter and clip position related: so I might have to raise the needle. JD did recommend the 5th notch, I went with 4th up from the spec of 3rd so one more might help. But I have to remove the airbox to do that and the first requirement for that change to happen is a big bucket of motivation.

The only change I made jetting wise on the dyno was to try 158 mains.  this helped the mixture, but not the power.  You get that.  It did help the way it felt on the road.  Or maybe the way it sounded.  It had that "noisy, but not really going anywhere" feel to it with the 152.

The next graph is power, showing before (Mikuni 38mm carbs) in green, FCR39 with 152 mains in red and 158 mains in blue.  Not sure if the pumps working would make any difference to the power over 4,500 rpm.  It's not a big power increase, and I couldn't give it the whack test to see if it was responding any harder and I ride the bike so rarely that I have no idea what it really feels like anyway.  In fact the thing that stood out that most was the much reduced throttle effort.  That alone was worth the work.

The next graph shows the air/fuel ratio change going from 152 to 158 mains.  Blue is 158, red 152.  Better, but still lean around 7,000 rpm and not as smooth as I'd like it to be.

So some more jetting work to do.  We'll see how long it takes to get done.  As this bike has been ridden maybe 6 times this year (including twice to the dyno) it's not a big priority given how well it runs now.

I would like to do the larger main air jet thing, just for the experience.  I'd really like to do some extended testing of things like 1/4 throttle mixture variation based on main jet and needle notch changes, etc, but with the cost of dyno time and access (when Dave is working so am I) I'll have to wait unti I have my own running I think.

The last graph compares the same 152 main jets fitted to my M750 in blue, the 900SS with FCR39 in red and the 900Ss with FCR41 in geen.  As a very general rule the 750 has 16% less capacity than the 900, so on average the fuel flow for a given rpm should be 16% less due to 16% less air flow and therefore vacuum over the jet.  Which was similar to the flow area difference between the 39 and 41 too from memory.  I'm actually surprised the theory seems to be backed up, I wasn't really sure what to expect.

UPDATE 09/10/12

Today I solved the accelerator pump issue.  Not really sure how though, as nothing looked like it had major issues.  I replaced the float bowl gaskets, accelerator pump o-rings and diapragm and within 7 throttle twists had fuel spraying.  Which was nice, as it wouldn't start yesterday without the pump working.

I also dropped the pilots to 48 and wound the slow air screws back in to 1 turn out.  There still wasn't an overly definitive change in idle with mixture screw variation though once warm.  It would idle with them fully in and 2 1/2 turns out.  I settled on 1 1/2 turns out from memory.

But, if it has cleaned up the very low throttle richness, I'll be happy.  Time (as in, when I get to go for a ride) will tell.

I also found that the 200 main air jets fitted as std are the largest Keihin supply.  So I ordered 2 pairs of 200 with the other parts and have 2.1 and 2.2mm drills on the way to make them a bit larger.  I'm curious, and there's only one way to fix that.

Thursday, October 4, 2012

Dyno chart for hot 1000SS: 1080cc, DP cams, Kaemna head, etc

Because the new Dynobike dyno reads lower than the old dyno, I don't have 16 years of reference for most of the dyno work I've done in the last 21 months like I have had in the past.  And one that I was quite curious about (and a little disappointed in originally) was a 1000SS race bike I tuned.

I first saw this bike when I fitted a U59 ecu to it back in the Moto One days and tuned it at Broadford on a practice weekend.  At that point it was 1080cc with heads by Kaemna in Germany and a full system from Mark at Madaz which had the 45mm header pipes going up through the middle of the swingarm and two mufflers under the seat.  Owned by a man named Drew, previously the Bears Formula 2 class national champion on his Vee Two Squalo, the bike had a bit to live up to.

After a couple of seasons as was, Drew brought it back for me to fit some DP cams and 748 throttle bodies modified (well, it's a bit more involved than simply "modified") by Kaemna to fit.  The job took the usual twists, and due to a tight valve the horizontal head came off.  Which made it quite clear that the compression wasn't that high.  I'd almost say it was std-ish.

See some photos of the throttle body set up below.  I refitted the std airbox, albeit quite modified as required with the handsaw and die grinder as this was the easiest way to mount the battery and ecu.  The original 748/916 trumpets were used, but shortened so overall the inlet tract is quite a bit shorter than your std 1000 motor.  It doesn't appear to have affected the shape of the power curve at all. 

Once the big throttles were on and the cams in (set to 112 degree inlet centrelines) I took it to the dyno to remap the U59 ecu.  I made some guesses based on the changes made for a baseline and as it turned out I was pretty much spot on.  Given it's a race bike I've not ridden it, but Drew said the cams and throttles made a noticable difference.  I was a bit let down by the power output, but in comparison to the two 748/853 and a 996 I've had on this dyno I'd say it's at least 15hp better than a 1000SS with pipes and air filter mods.

The graph below shows the comparison with the 853 in red and 996 in blue.  The 1080SS is as good as or better than the 996 up to 7,500 rpm (which is about what you'd expect in a 2V vs 4V comparison) and as powerful as the 853.  And I'm quite sure it carries a compression disadvantage.


Modified airbox to carb rubbers for 2V carb Ducati models

For the background on these dyno runs, see the first page of this post on the Monster forum and the photos about half way down the page.  Basically the rubbers from airbox into carb are cut off at the airbox level and the inlet radiused.  This shortens the inlet tract by 20mm.  The thread starter is a local fellow named Tony who is quite an accomplished fiddler and handy tuner.

Tony traded me some shortened rubbers for some more original ones for him to modify and I took the chance today (not being at work and all) to take a trip to the dyno and try them out.  Graph below.  Not really much of an improvement, but it's on the better side of the same so I'd say it's a valid theory.  Whether or not it works better with FCR instead of the Mikunis I don't know.  Red is short, blue std.