Saturday, July 30, 2016

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.

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