Tight cams

Grant said:
Roger, is it possible to swap the offending cam bearing with another?
Click to expand...

This was one of the otions tried in the trial and error stage - it made no difference the other worrying thing is normally the inlet cam runs free, if i put the inlet cam on the exhuast side it nips up so there is an element of head/bearing issue here, but also if i put the exhaust cam on the inlet side it also nips up.

It seems therefore that the cause is multi factorial - part cam part head/bearings. Bu***er, Bu**er.

 
Sounds to me like you have a head deck height issue. Maybe a DPO has tried to address this by 'modifying' the cam bearing heights already?
Have you measured each cam bearing height (from bottom to base circle)?
Any way you can put a flat surface over the head (without cams installed) to check flatness at each cam bearing location?

If the head is buckled then even a new set of cam bearings may not solve the problem.
When did you notice this? Was it the first time you had checked, or was it turning freely before this incident?

I am sure they can run for many miles with cams not turning freely, just not ideal, lose power, and may ultimately lead to issues with wear.
 
I had a cam very slightly bent, and had it straightened. No probs after that. From 3 thou to 1 thou.

Cheers,
Jacques  ;)
 
Have got hold of my steel rule now, the head appears flat.

The shim under one side of the cam block seems to have sorted the tightness, Which I presume would not be the case if the cam was bent.

The next question is that as the cams are FI regrinds from Keith the clearances have opened up especially on the exhaust side - so is it possible to get shims in the range 3.1. 3.15 and 3.20mm
 
Stock shim thickness ends at 2.90mm, 3.00mm appeared with the 1000SFC.

Need to look elsewhere.... :(

Have used a short-term bodge of placing appropriate pieces of feelerblade between shim and valve, worked well till I got around to removing the head to put things right.

piet
 
Roger

My understanding is that the Ducati 7mm valve stem is a tiny bit smaller diameter than the Laverda one, and the Ducati shims possibly won't fit over the end of the Laverda valve. I know when I tried a Laverda valve with an assortment of Japanese dirt bike 7mm shims, some fit (a bit tight but they went on) and some didn't. I guess you could measure the actual end of your valve stem, then take a good set of calipers down to the Ducati dealer and try to pick a shim that would fit.
Unless someone has already tried this?

Ken
 
Andy - I have a new chain from Keith.

Re Ducati shims - The other option which is a bit labour intensive is to pull one out of the 916 and see if it fits....

Having said that - measuring one of the valve stems they measure 6.8mm
 
My son has made and hardened some big shims for me, greater tyhan 3.0mm  but I cant remember what,swo they are available. however.......
In the 70's we were told that the factory's own mechanics would always give the cams a fair old "larraup" with an alluminium drift directly onto the camshaft, very close to all three bearings,this being on new build engines or repaired ones, I have never seen it done, or had to do it myself, but maybe, just maybe that is all you need to do.
CLEM
 
Keith diagnosed slightly bent cams  in my bike, and I had for quite a while struggled with the tight bearing problem...I cheated by getting a new head, and new billet cam blocks. Enjoyed the e-mail from Keith a short while back informing me that it all spun up "free as birds". certainly does that now, so much so the rev limiter on the Red/Sachse ig system is a must ;)
Nick7
 
C'mon Nick, never mind the Sachse or the free running cams, you know which feedback we're really waiting for.... :D :D :D
 
Wolfgang stocks 7.0mm shims in thicknesses up to 3.30mm
have them in my own shim stock

 
Good news - Keith can supply oversized shims. so looks like should be able to get near start-up soon.....
 
I know he is based in Govan, but I thought the last ship sailed from there many years ago...
 
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