Cam chain length Alpino 500

corsaro

corsaro

New member
Location
York UK
Just assembling the cam chain on the 500 Alpino, I checked the length and it is 112 links which appears correct. Even without the rear chain guide installed the chain is tight - even with the head/barrels torqued down . from what I can see the head and base gasket thicknesses have an effect on the tension as they determine the length over the sprockets from the crank up through to the cams. The chain has the correct run - on the crank sprocket, within the rear pin that holds the rear chain guide.
The question is - am I missing something, I could fit a thinner base gasket to gain a little slack in the chain - but it would be minimal
The cam bearings are new needle rollers throughout. I expected on assembly that the chain would be worn as the bike in theory has completed 33k km and hence I would have the other issue of not having any adjustment left on the rear adjuster.
 
Where did you obtain the chain?
It is a bit of a bugger of a job if I remember. I seem to remember putting the chain on the cam sprockets with the cams nearly on the timing marks and then turning one of the cams the last few mm.
Paul
 
you could be right on that Paul but you do have to do that with 4C cams in 180 triples, so maybe you have crossed wires, more likely to be the chain is not on the crankshaft sprocket but running along side it, it will turn and even run like this but not for long.
CLEM
 
CLEMTOG said:
you could be right on that Paul but you do have to do that with 4C cams in 180 triples, so maybe you have crossed wires, more likely to be the chain is not on the crankshaft sprocket but running along side it, it will turn and even run like this but not for long.
CLEM
Click to expand...
Could be Clem but I've never installed 4C cams.
The 500 is a bit of a bastard, the standard cams won't stay put with the timing marks aligned. Pressure on the cams and there's plenty of those.
Paul
 
Thanks for replies . The cam chain came with the bike and had obviously been fitted in the past. It is a Regina of the correct type. The chain is correctly on the crank sprocket and the cam sprockets. When the right and cylinder is on tdc ( checked with dial gauge prior to ), the exhaust sprocket can be aligned easily with the timing mark , the inlet needs to be coaxed round to the correct position with a ring spanner on the inlet sprocket locating screw. Apart from the tension on the chain the only issue seems to be that it is difficult to get the sprocket and timing marks exactly aligned due to the position of the chain on the sprockets. - as one can move them in relation to the crank - one tooth forward /one tooth back
If I believe the mileage the bike as done the cam cain will have completed 33k km if it is the original - so I would have expected a little stretch
I will continue my investigations.... but gasket thickness seems to be critical to the alignment.
 
The tensioner is not mounted - On Breganzane I found the following information ..
Many years ago (20+!) there was a bad batch of Regina C121HCS cam chains which were not produced properly and ended up "short". These show up by being very tight, having no slack at all when installed. They should NOT be used as they fail very quickly, causing lots of expensive engine damage. Amazingly enough, some of these chains are still showing up from time to time, so be aware.

With the above in mind I laid out the chain and checked the length - in theory the chain should be 112*8mm = 896mm pin to pin
The chain as measured with 112 links is 893mm and this is not a new chain so my conclusion is that it is one of the short ones.

If this is the case - there is a logical explanation, so now the search is on to find another one which will fit.
Stu
 
corsaro said:
The tensioner is not mounted - On Breganzane I found the following information ..
Many years ago (20+!) there was a bad batch of Regina C121HCS cam chains
Click to expand...

That story I'd heard related to triple camchains, (C121) the 500 is different (C107) as laid out on that page. So something weird is going on but not that. Obviously most normal issues you might expect (stretched chain, skimmed head or barrel, etc) would always make the chain looser rather than tighter.
Post a close up photo of the chain, perhaps the 500 experts can identify if it's legit. If the bike is new to you don't assume that anything is right and original. Have you had the engine apart? Previous owners do some weird shit.
 
thanks for the clarification, my mistake it was indeed the triple cam chains with the issue.Every day is a school day!
everything seems to be ok in the engine so I am sure I will sort it with a bit more investigation.
 
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