Weird one… I have built a special from an ST2 and it has gone to plan so far. When I start it, it runs well and will pull away in first gear. However, after about three times starting, revving and selecting first it will stall dramatically when I let the clutch out. I can’t take out at the moment, because it’s not road legal, so I’m just mucking about with it in the driveway. I thought initially it was the clutch (still could be) because it is really difficult to find neutral, but bled it and cleaned the plates and it seems to work better. That’s when I noticed it stops working after the third start… Any thoughts? Possibly electrical? Plugs seem to be fouling up with carbon really quickly…
My old Bonnevilles used to do that! Simply pull the clutch in, and apply the kickstart several times! Whaddya mean, you haven't got a kickstart? Yeah it does sound like clutch drag.
Would you say it was stalling as though the ignition is turned off? just a long shot, but have you got a "clutch switch" on an ST2? - I know that if you have one, it should cut the ignition as soon as you pull the clutch in, not when you let it out but still wonder if it's relevant.
I’m certain there is no clutch switch… I imagine it would look much like the little brake switch on the right hand lever? I just tried it again to better describe the action. I started it and selected first. I could then roll it forward a few yards letting the clutch out. Did this a couple of times, but the third time I let the clutch out to roll forward it stopped dead! Quite a noticeable mechanical ‘clunk’ which doesn’t sound very nice. It basically stalls the engine. If you rev a bit more and try slipping the clutch it just does the same thing. Clunk and stall!
My guess it still could be the clutch plates or height of them , pump on the clutch lever or the slave cylinder.
Is there rock on the clutch basket/hub? (i.e. loose centre nut). It sounds from your description to be a mechanical issue.
I didn't think anything prior to the 749/999 had a clutch micro-switch. Surely with a well set-up dry clutch, there should be hardly any 'clunking'? It does sound like a mechanical issue to me.
I think your last sentence holds the key to this, it's tracing the "clunk" now - have you dismantled clutch or anything recently? When was the last time it worked normally (if at all)?
I bought the bike last year without taking it for a run, but it did start up and select gear etc quite happily. I haven’t split the engine or done any major mechanicals. I have swapped the clutch slave to an Oberon (original was leaking). I’m getting around 2-3mm of pressure plate travel… Just tried spinning the clutch pressure plate while disengaged and it feels okay. Possibly a bit of drag. Does anyone know how much travel I should expect?
If it can select gear easily, without the massive "clunk", then that's a very good start. you only need 2mm of movement at the pressure plate to fully disengage on a std Ducati dry clutch that's assembled correctly.
i haven’t been into the clutch that deep, but can hear a bit of backlash style gear engagement when I rock the clutch in neutral. Sometimes the final drive shaft (the one the small sprocket bolts to) spins silently, when turned by hand but other times it sounds like it ‘catches’ lightly on the gearing.
Have you taken the clutch plates out and examined the clutch basket for notchy grooves? And likewise the tangs on the plates?
Well I had a look and took a couple of pics… I have seen worse, but there are some grooves in the basket.
Okay, I gave the whole clutch and basket a good clean to improve the lever feel. The grooves are simply not deep enough to start worrying about that, so after I put it all back together I filmed my attempt to pull away... I am restricted to a very short section of covered drive way: The video shows the rather dramatic 'clunk' I have been experiencing. It's not the kind of thing you want to be doing too many times. Also (as mentioned before) I tried a few more revs and more clutch slip, but it doesn't help. Still the clunk. Thoughts very welcome.
Thanks for that... That's a proper pain to replace, but done it before on a 748, so at least know what to do. With the 748 it was more a rattle on starting than a stall, so does that mean there is a little more damage in there?
It's an unusual one as you seem to be able to start every time practically as normal. I've not experienced first hand but have heard several times how a distorted sprag clutch can cause unusual noises while engine running but yours is actually a "jam" severe enough to stop engine so best to hope that others reply having experienced this exact symptom.
Some further fiddling and I have discovered a light interference noise, like it is catching on a gear or something. Another video: Doesn't do that every time though.
yes! - you are getting closer! I wonder if it is the broken selector spring jamming on an idler gear as p.m.'d. if it was a foreign body merely loose in the crankcase then from my past experience it does do the dramatic "clunk and jam" (just as yours does) but it doesn't do the repeated "rubbing/whirring" sound that you are experiencing, as though whatever is causing the interference is loose enough to move around to some degree but is still "tethered" (which would fit in with the broken idler spring end).
