Good question.   My guess is a miniscule amount.  You'd actually have to measure overall chain length on a new chain vs a stretched chain.   The difference  divided 2 (chain is a loop) would probably be proportional to the % of valve offset.   It seems like one thread in here did mention the amount of stretch you could expect to get on a worn out chain.

Maybe a degree but not enough to matter.

You're allowed about .060" chain stretch.
for each .010" you get about 1° of cam retard.
if you were racing, it might matter.
otherwise, I don't think it matters.

Naaah, snow is okay, its that blasted Ice ya get into,, BUT,, with some outriggers & an arm off the back of the frame with a spike & some cable & an explosive charge so you can "Drop Anchor" in an emergency, I dont see any reason to park it,, Well,, except for the occasional car skidding across the road or thru a stop lite,, hey,, I can picture riding thru the winter in Idaho.. suuure I can,, Im not really able to picture surviving it,, but, hey, how will ya know if ya dont at least try, right?

that might have been taken into consideration, might not have.
it's been a couple of years since I've done it.

At 65, I still have a memory like a steel trap, snap shotting virtually everything I see  ...ummm, except WHERE I saw it!    

Zuk's service manual...

CAM DRIVE CHAIN 20·PITCH
LENGTH
Pull the chain tight to remove any slack, then using
vernier calipers, measure the 20-pitch (21 pins)
length of chain. If it measures more than the limit,
replace the chain.
Service Limit 128.9 mm or 5.070 (.070 over)

The 20 chain links measured is almost exactly 5 inches in length on a new chain, from the front of pin 1 to the front of pin 21.   The .070 stretch limit is 1.4% which equates to just over 5 angular degrees of lag on the cam sprocket (1.4 X 360 = 5.04).   So make sure you are NOT measuring the entire length of the chain when checking service limit.  For instance, lets say the overall chain length was 25 inches.   In that case, the service limit when measuring the ENTIRE chain would .350 inches of stretch (.070 X 5).

justin_o_guy2 wrote on 07/07/12 at 10:17:53:


Hmmm, I don't think so, but now you've got me curious?   My thinking is that the 1.4% is absolute length increase, no matter whether you measure the whole chain or one link.  As such, it corresponds to the rotational angle difference (lag) between the driving gear and the driven gear.  I wish I had better sim tools (or the brain I used to have before all the drugs, drinking, fast women, and other debauchery of my youth).

In any case, the point was that the .070 service limit was over just 5 inches of chain, not the entire length.  I didn't want members to be throwing out chains that had only .070 on the whole length, which would probably be garnered in the first few thousand miles.