Sunday, July 31, 2016

Rebuilding MV Agusta F4 mirror mount posts AKA when those stupid little knobs on the bottom break off and the bloody indicators won't work anymore.

I had an MV F4 come in with one of the front indicators not working unless the screw was almost loose because the stupid little cast on lugs had broken off the bottom of the mirror mount.  If you've worked on an F4 you've probably had it happen as you tighten the front fairing mount bolts.  Do them up tight on some - no problemo.  Gentle as can be on the next one - break.  They truly give me the hibbidyjibbidies.

On this occasion I thought I might do some thing about it.  I measured the knobs on the other side and they were 5mm diameter, so I drilled the mirror mount at the broken points, tapped some M5 threads into the holes, loctited some M5 screws in (long shank ones with the threaded section precut to the desired short length) and then cut the end off the screws so the desired shank length was left.  As per the photos below.  I was rather impressed with the results I must say, even if one is a bit angled.  It's all done freehand due to the impossibility of holding anything in a fixture.  Unless, of course, you'd made a custom fixture beforehand.  I didn't have that much time to hand.  And yes, the indicator now worked with the screw tight.





Clutch pressure plate bearings and the like

Third 748 story, this one a 1997 SP.  The owner was complaining of the clutch losing pressure over time.  Fluid level was ok, colour typically not, no obvious leaks, aftermarket slave.

I removed the slave to check for the rubber bellows (there, but fitted the wrong way around), but found a short section of pushrod stuck in the end of it.  There are two o-rings on the pushrod that goes across the engine, just inside the cases on the slave side.  On the later 3 phase alternator bikes, a pushrod broken at one of the o-ring grooves is a very good indicator of the flywheel nut being loose.  But this was an older single phase alternator bike, and it didn't sound like it had a loose nut to me.

But I thought it might be more likely to have a seized bearing in the pressure plate, which it did.  Totally seized.  This is one of those issues that suddenly started appearing after many years of none at all.  I see quite a few 2000> era bikes with the bearing seized (or at least rough), but not older ones.  Late model bikes have a pin through the pushrod at the LH end that locates in the slave cylinder boss and stops the pushrod spinning, which is a typically involved solution to a seemingly simple issue.

The bearing in the pressure plate is a normal ball bearing.  I always figured it was used somewhat poorly, given it's not specifically a thrust bearing but someone who knows bearings told me once that it was probably just fine.  Maybe, like the 2002 ish onwards front wheel bearings, it's a bearing quality issue.  Although on this bike the pressure plate was aftermarket, so a non Ducati bearing.  Possibly worse.

As the pushrod had been spinning, it was quite stuck in the slave piston and had probably damaged the slave bore.  The easiest solution was to replace the pushrod with the later, 2001> longer part and fit a new aftermarket slave, in this case an Oberon as they are both well priced and, from my experience, well made.

It also had the usual wear at the centre of the hub, where the big steel washer slowly eats its way back into the hub.  I see a lot of this, and if the wear is not great you can add another washer to take up the clearance.  Clearance here allows the hub outer section - the splined aluminium piece - to move in and out on the cush drive rubbers that sit over the steel inner section.  This translates as excessive freeplay at the lever, as the movement of the hub moves the pack and pressure plate with the hub without lifting the pressure plate off the pack.  As an aside, I have seen (and indeed fitted) up to 4 washers here to take up the wear when the budget doesn't extend to a new hub.  It's quite amazing how thin the hub can get and not fail.

I found a photo of the one that needed 4 washers.  You can also see the wear on the pushrod - the stepped section runs in the needle roller bearing just inside the end of the input shaft.  It's not meant to have a step.



Saturday, July 30, 2016

Odd alternator cover leaks

I'm on a roll now, so possibly the second in a three part 748 tale of woe.

I had another 748 in recently, just purchased sight unseen from interstate from a shop I believe.  Allegedly a low km (3,500 miles) import, clearly bought from a bloke with a very long nose and charred pants.  It's really sad to see people get ripped off like this.

Apart from a couple of basic and unmissable compliance issues - LH drive headlight and non approved braided brake hoses - it had undersize front brake discs, front brake and neutral lights not working, steering stop broken off the frame, rusty steering head bearings and more.  Minor detail stuff too, like normal screws holding the mirrors on instead of the brass, breakaway head screws, screws holding the seat on instead of the plastic pins and rubber keeper and no tank pin grommet in the front of the airbox, which was contributing to the steering damper taking the paint of the front of the tank on the RH side.  Again (self righteous wanker statement time) just work done by someone who doesn't know the bikes or what causes issues.  Some of it well intentioned, some just sloppy.

I worked out the neutral light issue was that the dash / front section of wiring loom was for a late style single wire neutral switch, where the switch completes an earth circuit through the engine, while the neutral switch and rear section of loom was the older two wire 12V continuity switch style.  To make the light work I left the switch wire from the dash globe connected, and made a little wire to go from battery negative to the other (originally 12V power) switch wire to earth out the circuit and bring the light on.  Simple, but never going to work as was.

Another was oil leaks from the alternator cover.  Usually they leak from the clutch pushrod hole, caused by the clutch slave (which is bolted to the cover) trying to pull the cover off the crankcases every time you pull the clutch lever and stressing the goop over time until it no longer seals.  Often the cover screw behind the slave is loose too, in this case it might have been too long and not bottomed. Anyway, I pulled the cover, looked for other obvious issues, cleaned, gooped and refitted.  I also replaced the rotation sensor o-ring (old two screw pickup, original o-ring now NLA) and applied some more goop, which I really don't like doing when o-rings are involved unless I really have to.

Then I went for a ride and parked it to see what it dropped and to my profound dismay it started immediately.  At which point the source of the leaks became a little more apparent.  Certainly nothing I've ever seen before either.  The video shows oil bubbling out from under some corroded paint near the top of the cover, around the unused boss originally for the crank sensor on P8 ecu models.


video

It had more leaks, under the DUCATI logo at the bottom of the cover and a couple up at the front of the water pump below the rotation sensor.  Again, just oil coming through.  I don't know if it's just porous or if it is residual crash damage.  While trying to find a replacement cover I spoke to Shaun at D Moto and he said in his DDT days that they used to see the race bike covers do similar things after crashes.  No obvious marks or damage on the outside or inside, just leaking.





Steel fuel tanks and rust - the sort that makes holes and creates much agro

I had a 748 in recently - 20,000km, overall quite clean, purchased a couple of years ago out of Queensland.  It had some marks on the engine cases showing some sort of "liquid from above" staining, and when I pulled the tank there were a couple of small areas of paint bubbling with a wet look about them (never good).  Removing the pump assembly showed the extent of internal rust.  Photos show some of the tale.  The crud around the fuel pump pickup was quite amazing.  The rust holes shown were exposed using a piece of Scotchbrite only, there was no real effort involved.  It's amazing to think it wasn't just pouring out.  I was discussing this with Brad at BikeCraft and he said he has had customers come in to him with tales of no leaks until it dumped a whole tank in seconds from this sort of rust damage.






If your bike has a steel tank, it's important to look inside it at regular intervals.  Make sure the cap recess drain is clear, so any water that sits in the cap recess will drain out, not run into the tank the next time the cap is opened.  Add something to remove water occasionally.  Every time I service a bike I add about 100ml of injector cleaner.  I use Wurth brand cleaner, I think what I get is the imported stuff that you can't buy retail afaik.    It's great stuff for cleaning injectors - I've had to reset idle mixtures after road tests sometimes just due to it doing it's job - but it's also good for removing water from the tank.  Metho also will do the water removal job.

Even plastic tanks can benefit.  Sometimes you can get a jelly sort of stuff build up in them, or you get the likes of the Cagiva Raptor, where its plastic tank has a bolt in fuel pump assembly with exposed steel fuel pump wiring.  In a triumphant masterstroke of engineering design, those terminals sit at the lowest point of the tank.  Right where the water collects.  Genius.  Luckily you can get the complete plate assembly from Suzuki as a TL1000R part - at around $800 (from memory) it's about half the price of the probably now non existant Cagiva part.

Another thing I see with plastic tanks is their cap recess drains blocking at the little screw in aluminium barbs in the bottoms of the tanks.  Often the rubber hose routing after the barb is such that there is an upward run causing water to collect in the barb.  They just fill with white corrosion, which can go surprisingly hard.  I find the easiest way to clear them is to run a 2.5mm drill through them, which also illustrates how small and easily blocked the hole is.  Best to remove them before you go drilling into them while they're mounted in a plastic tank, but then again I've had a few break off before coming out.  I now keep a couple on the shelf.  Any of the late model bikes with plastic tanks can suffer from this, including Aprilia and Moto Guzzi.


Ducati 2V timing belt adjuster bearings

I had an M1100 in recently (same one I pushed some time ago) to follow up on a poor starting issue.  I see a few of these in for valve clearance services (first clearance service, or first by me if I can say that without sounding like a self righteous wanker) where the owner will comment, often once finished, that the bike can be hard to start.  Or they'll ask me "did you have any trouble starting it?"  Usually I respond with a bit of a blank look and "no, fired right up".  But when doing the clearances I would have found lots of closing clearance and no opening clearance on the exhausts.  After setting the clearances the starting issues seem to go away, so it's the next thing I would normally check after cranking compression, leakdown and fuel pressure.  In that order because it's the most time consuming.

On this particular bike I found one exhaust opener with zero clearance, and the expected lots of closing clearance.  When I say lots of closing clearance I mean in the region of 0.15mm.  Many will recognise that as being within the Ducati specified range of 0.00 - 0.20mm.  In my experience, 0.20mm will cause you all sorts of idle and low speed issues.

Not that it made any difference to this bike.  Still not a happy starter, taking 3 or 4 cranking cycles to fire and run.  I did notice, when doing the clearances, that it was very, very hard to turn the engine backwards with the rear wheel.  Fine going forward, very hard backwards.  The difference here is that turning the rear wheel in the direction of normal rotation just turns the gearbox and crank.  Going backwards engages the starter motor system through the starter clutch, and although the drive ratio means the starter spins much faster than the crank, it still should turn rather easily.  I have seen a few idler gears weld themselves to their stud over the years, and I'm curious about this one.  It will have a Motolectric starter lead kit fitted next, but I get the feeling I'll be pulling the alt cover following that.

Anyway, none of that is why I'm writing this.  Today's rambling is about what I found when I pulled the belts.  This bike has done 26,000km, and had a 24,000km (meant to be a valve clearance) service done within the last year I believe.  I always spin the belt adjuster and idler bearings to see how they feel, and on this one both adjusters felt a little rough.  A little rough means they get replaced.  The horizontal idler was making a very dry noise, so I added it to the list, then looked at the vertical idler.




It was completely seized, and you can see how hot it has been from the belt rubbing over it.  I have seen a few M696 with this bearing failing or failed on the vertical cylinder, all around 36,000km.  But not one this bad.  So it got all idler and adjuster bearings (supplied as complete assemblies only these days from Ducati) and a pair of belts.

Something to keep an eye on.



Monday, July 11, 2016

Another dyno debacle with Minnie the 400 - Ducati Monster 400 dyno runs

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So, I had some time today to return to Dynobike with Minnie.  Last time, some weird stuff went down with dyno interference.  This time, I had some different Kokusan ignition units fitted and took along a couple of Ignitechs - my old one with the last curve I ran, and a new one just in case.  I checked them all with the timing light before hand and all the units (2 pairs of original Kokusan and 2 Ignitechs) had the same idle and full advance, with my old Ignitech taking longer to get there.

My old Ignitech and the Exactfit ignition coils have been on this bike with the 750 engine on this dyno before, so I figured that, if required, that set up should ultimately rule out any issues.

Bup bow.  Wrong again.  I forgot the Ignitechs would have had the rev limit set at a normal-ish 9,000 rpm.  The 400 goes to 11.  Plus they seemed to have a misfire of sorts.

Anyway, eventually some runs without rpm or air/fuel (the bike shuts both of those dyno functions down) were made, comparing cam timing settings and std vs the all conquering Megacycle mufflers.  As below.  46 mph = 5,500 rpm.  80 mph = 9,500 rpm, 93 mph = 11,000 rpm.  Ish.

Megacycle mufflers fitted.  Comparison of 108 degree inlet centreline cam timing in red, 120 degree cam timing in blue.



Same as above, but with std mufflers.  The interesting thing here is is the angle of the power curve right at the end of the 120 degree run.  You could hear it on the dyno too.


Clearly, no matter what else you're running, 108 degree inlet centreline is the go.  I had the pullies drilled for 112 and 116 too, but I wasn't going to waste anymore time with what seemed like pointless experimentation.

Next, std mufflers in blue versus Megacycle in red with cam timing at 108 degrees.  Odd linear straight line bit between 25 and 45 mph, hole between 50 and 60 mph.  


With the cam timing at 120 degrees, it's pretty much the same thing with a bit less everywhere.


For a bit of a starting point to final comparison, std mufflers and 120 degree cam timing in blue, Megacycle and 108 degree in red.  Up to 15% better in places, but then again, 15% of not much is quite a bit less.  The red curve power goes flat at 9,000 rpm and peaks around 9,500 rpm, so you can shift earlier too.



Finally, a sample of the frustration.  Blue is the run from the first session two and a half months ago.  Red is the same set up from today's session.  The only change is the ignition control units, one pair of original Kokusan units replaced with another pair.  But even more confusing is the green curve.  That's from today as well, with the Ignitech unit fitted (the new one from memory).  It had a bit of a misfire through the rpm range, but it's about 20% stronger than the runs with the original control units that followed minutes later.  If someone can explain that to me I'd be very happy.



Lastly, what timing belts look like going to 11,000 rpm.


video