Tight RGS cam chain: new gaskets

Rob

Rob

Hero member
Location
Midlands, UK
I know tight cam chain problems have been debated before, and have re-read all that has been said.  As a result, I dived back under the engine to recheck I hadn't left half a link standing proud on the crank sprocket and that the chain was properly engaged on the teeth.  Then just for good measure, dropped the chain off the crank sprocket and re-engaged it.  Nothing found amiss....

Problem is as follows: replaced barrel & head gaskets (Athena) on RGS.  All torqued down OK - original cam chain rejoined with a bit of slack, but not as much as when I removed it.  The slack (10-15mm chain movement) disappears after reinserting the tensioner blade.  There is just about 5mm movement with everything backed off and after judicious straightening of the blade (slightly distorted curvature where tensioner wheel sits).  The cam chain tension is applied when the last 40mm or so of the blade is slid into position....it needs a very firm push to move over the edge of the crankcase ridge.  In fact I have had to resort to removing the tensioner assembly to push the blade past the ridge.

Question - is it to be expected that new gaskets would take up about 10mm of cam chain slack?  (The old gaskets were probably original factory fit).  If not, any ideas about what to check next?  Engine runs very well.....!  Was wondering about getting a decent quality replacement cam chain and threading that through.
 
Brad,

Don't straighten the tensioner blade, this will cause the cam chain to bear on the lower un-coated part of the blade.  I always give it a good bend before installing a new one, either bend the lowest bit back about 15-20? or give the whole blade a bit of curve.....

Stock gaskets compress to about 1mm thickness, maybe the Athena items are indeed a bit thicker... still don't see them taking up so much slack, though.  5mm up and down of the chain between the sprockets is more than enough, depending of course how hard you're tugging on it! :D

piet
 
A new gasket will not, or should not take up 10mm so something else is wrong, maybe on the tensioner.

Although feeding cam chain through is technically unsound millions have done it over the years and  had no problems.

If you do go for a new cam chain check that it is not full of grease or lube. For one cam chains are just about lube free, industrial product is greased. Also although many quality industrial chains are fine for cam drives the grease does take up the free tolerance in the chain sometimes making them difficult to fit. If you must use a greased product best to shove it in petrol for a few hours to remove the grease. How politically incorrect is that  :D :D :D :D :D

Andy
 
hello Brad, me and Sheepy had this with his SFC1000 last year, the Regina cam chain that he had in his stock (new/unused,but in stock a few years) was so tight that the tensioner blade could only just be inserted into the tunnell, and that was with the adjuster unbolted and on the bench.We wound it out again and fitted one of Andys Iwis chains (which I took with me for precaution) and all was well.This is a factory engine, never dismantled, the Regina chain that was factory fitted was totally different to the Regina chain that he was intending to fit purely as the original one was past is change by date.The original had pronounced domed pins and the replacement was much lighter looking with only small splayed ends on the pins,it did not have "3M" on it.Both Regina chains went in the bin.
CLEM
 
Thanks all for contributions. 

Piet - thanks for reminder about tensioner blade needing to be bent / curved.  It still is - my 'straightening' was an attempt to regain a smooth curve along the blade length rather than one that is kinked half way along where the tensioner wheel rests.  It also has a sharp 20 degree bend where the rubber backing ends

Andy/Clem - yes, I'd understand if I had swapped the chain during the gasket change, but I didn't....hence my concern!  Will be in touch Andy - the installed Regina matches Clem's description - paranoia has taken hold!
 
Hi Keith - not me - was on the bike when I bought it so at least 4 years old....there again, it seems clear that Regina have changed what they produce so who knows? 

The bigger mystery is why it's now tighter than before the gasket change.  Thar be dark forces at work  :undecided:  Should have put up with the oil leak and just carried on riding the thing!  :D
 
Hey, when in doubt, go to Andy.  He'll take care of you.  No worries!
 
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