Twin cam chains

  • Thread starter Thread starter lemonjelly
  • Start date Start date
Then the Regina is not to DIN I will check with Glen after the new year.

Lemon all quality "cam chain" has spit roller due to occasional failures of
solid rollers as engine revs increased, even Regina has industrial and automotive
quality in 06B.

Just checked the Renold bible for 06B sprockets machining and roller is given as 6.35.

Run Regina 06B dimensions through google and it also says 6.35.......very odd

Andy
 
The last time I rebuilt a 750 I put in a new Regina cam chain. It was impossible to connect the chain ends unless the head was fully torqued down. Even then it was very tight.

Bruce
 
maybe this "prestretched " originals Wolfgang says is true then?
 
lemonjelly said:
Wolfgang says they were prestretched but how can you stretch a chain?
Click to expand...

only way that I can envision someone pre-stretching a chain is to install it in some contraption that somehow puts it under strain and thus lengthens it somewhat
so in effect, you are wearing it out before you even install it

Keith's reply about the camshaft to crankshaft centres makes more sense




 
Prestretching is actually pre-tolerancing.

Basically the chain comes off the production line goes round some sprockets,
the machine then stops and rams jack the sprockets out to the DIN designated
tolerance. All happens in a fraction of a second.

With automotive chain, at iwis anyway, it is then pre-run up tp engine speeds
before being shipped.

This is part of the reason we should not put our faith in terms such as "made to DIN"
and "made to European tolerance" as all crap is. It is a measurement not a quality
standard.

I would think the problem with cam chains is simpley variation in engine tolerances as
many folks have no problems with Regina or iwis and many dont. Years ago there was
a great variation in chain lengths but with modern quality chains this should be not
a problem.

The chains I supply are from Mercedes etc and the variation they find in millions of engines
is zero.

Ye gods its still Christmas and I am ranting.......sorry folks

Andy
 
I learned from a recent problem with a BMW alternator belt , that even if it says on the tin , and the belt, that it is the right one, use your noggin if it seems too tight, and don't fit it. There will be one that fits properly somewhere without being so tight as to destroy bearings...
 
I?ll add to this although it is a while since.
I just tried to fit a new IWIS camchain to an SF2 motor I am assembling for someone. It has the same problem as mentioned here. With the head fully torqued down and sat overnight, there is a bit over half a tooth short to get the chain into place. I have the exact same camchain in both my own bikes, but these have had the compression increased by skimming the head and using thinner 0.5mm base gaskets. The current motor that I am assembling has not been skimmed at all and has "standard" gaskets. It seems to me that the problem is caused by either, as Andy mentioned, the plates are riding up on the inner of the crank sprocket, which seems unlikely to me but I don?t have a crank here to check, or the factory tolerances of the height of heads and barrels, and the gaskets that get supplied now. I can?t go to a thinner base gasket on this motor as it is just under 10:1 already as it has some oddball JE pistons with high crowns and huge deep valve cutaways, so I measured chamber volume.
For this motor it is impossible to use the IWIS.
 
He also used to suggest washing the chain in petrol to remove any grease, thus potentially allowing it to fit better.
Worth a try.
 
Grant said:
He also used to suggest washing the chain in petrol to remove any grease, thus potentially allowing it to fit better.
Worth a try.
Click to expand...

Works well. You gain quite a bit. Surprising.

Paul
 
Soaked it overnight and got out any oils, gained enough to force it down onto the correct teeth but it would need a lot of pressure to get the link in there. That would put far too much strain on the cam centre assembly for my liking. I?ll save this IWIS for another motor and source another brand for this motor. The chain measures only 2.5mm shorter overall than a new Regina that I have here which fits just right to the motor, and with my verniers there is no measurable differnce in roller diameter or plate cross section. A puzzle.
 
Maybe you didn't get all the grease out of the chain. Try washing it in petrol a couple more times.

Do you have chain tool like the one below for pulling the ends together? If you can get the link on and run the engine for a bit it'll probably loosen up.

 

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Dellortoman said:
Maybe you didn't get all the grease out of the chain. Try washing it in petrol a couple more times.

Do you have chain tool like the one below for pulling the ends together? If you can get the link on and run the engine for a bit it'll probably loosen up.
Click to expand...

chain tool like you have shown will never work on a 750 engine, there is only a single sprocket and restricted access to it so there is no chance of using that tool
 
redax5 said:
chain tool like you have shown will never work on a 750 engine, there is only a single sprocket and restricted access to it so there is no chance of using that tool
Click to expand...

OK. I use one of those tools on the triples, but the single camshaft thing hadn't occurred to me. Is it obvious that I've never worked on a 750 engine?  :D


 
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