Metalic Clunk After Belt Change

[grillphil]

HI,

After fitting new belts to my M600 & starting the engine for the 1st time, a metal clunk was audible and felt through the bike as if dare I say it, the piston was hitting an open valve. I have checked the timing marks and they are spot on and before re assy, span the engine by hand to make sure all was fine without the plugs in.:shocked:

This happened when cold, 3-4 times intermittently over a 4 min period, at idle on choke.

Could this be a sticking valve or something more damaging. Can these engines be flushed before an oil change?

[dlloyduk]

sounds like a valve to me, marks would still line up if you were 180deg out with your timing marks? I would check a again before trying to start it again.

[Pedro]

If it ran then the timing must be ok, if you had it 180 degrees out it wouldn't start. If a piston hit a valve I rather suspect you'd know but the shrapnel....

Did you remember to tighten up the tensioners properly, could be one flapping about. Again, worth checking before starting again, whip the belt covers off and check everything.

Ped

[Rockhopper]

Check the belt timing marks are lined up and then check in the little window on the left hand side to see if that mark lines up as well.

[grillphil]

I'll check it all over again tomorrow as you all suggest. The tensioner bolts are like cheese, cr*p material as usuall. I have some stainless ones which I think I'll grind the heads down and refit at the same time, after all it will only take 30 mins to do.

I'll report back tomorrow.

Cheers guys for your help.;)

[CK & AK]

wot Pedro said & others.

Undo, check tensioners, check ALL markings line up

If you have done all as you said and the engine ran before & you didnt move the engine at all whilst doing the belts, it should run fine.

Never found any tensioner bolts like cheese on any ducati's I've done so far, so am really baffled about you saying this - unless I've been very lucky.

Alan

[Pedro]

Alan

both tensioner bolts on mine were cack too when I first did the belts, Nik Codling found the same on Emily's 600. Had to drive a slightly bigger hex drive in to get it out.

Ped

[Pugi]

Mine were rubbish to, had to be drilled out. I could feel the new ones giving way as I tightened them too (with torque wrench to spec., mind you).

[gary tompkins]

Never found any tensioner bolts like cheese on any ducati's I've done so far, so am really baffled about you saying this - unless I've been very lucky.

Alan

Errr... yes I think you have Alan?

The plastic bolts in my 2 Y.O. nephews Bob the Builder play set are far better quality :thumbsdown:

Replaced both mine with high tensile hex bolts, so I can use a pukka 13mm socket now ;)

[grillphil]

cheesy screws all over the duc!

Well. i've checked the timing marks again and the tensioner bolts and they are all tight to spec. Belts are at 10lb force as per spec.

Started again from cold and this clank, metal to metal still there. As the tank was up, it sounds like it is comming from the vertical pot top. Could this be a sticky valve or at worst a broken spring?:shocked:

I'll run it up to temp at idle later and report back.

[Ade]

Does the noise disappear after it warms up a bit, shims maybe

[Rockhopper]

Don't think it can be a sticky valve because they are mechanically closed (that what the desmo system is all about). The only spring in there is a light helper spring which just helps to keep the valve shut.
Are you sure you got the right belts? Some M600's have belts with round teeth and some have belts with square teeth.

[grillphil]

The belts which cam off were 066029090 & the same fitted. Square teeth on the belts too. can anyone advise if they are to be round toothed for a 1995model M600?

I suppose the next thing to look at will be the shims.

Seems to go when the engine is hot but i'll take it for a spin to High Beech tomorrow to see how i get on (AA phone number stored in phone too:shocked: )

[STIVH]

My 95 600 clanks all the time until warm. I have been told by several people in the know!! That on the early models the pistons were made with some tolerence to allow the pistons to expand when warm and that the slapping can be very noisy but of no concern.

However if it wasn't there before possibly the tighter tolerences caused with the new belts may just be allowing you to hear the engine clearer, as an aside from this does the noise disappear when you engage the clutch or/and with any gear selected?

[Shauns4]

I suppose the next thing to look at will be the shims.



if the noise started after changing the belts it won't be the shims, they wouldn't make the sort of noise you mention anyway.

Shaun

[grillphil]

Mmm. When the clutch is pulled, the clotch then makes it's own noise. Thats another thing altogether. I'll take it for a spin tomorrow and report back.

Cheers guys for all the input ;)

[Pedro]

600 motors are prone to what might be called excessive piston slap - they almost ring like a bell. Nothing to worry about really

Ped

[grillphil]

Well, seems to run fine without any need for ringing the AA. Noise goes when run at temp too so i'll put it down to the pistons.

I'll go for a longer run tomorrow but i'm sure it will be ok.

Cheers guys;)