[monza4me]

Ive been experiencing what I believe is chain noise in the upper end on my trusty 87 250X. Ive removed the valve cover to see the chain and guides in good clean order. The cam tensioner mechanically operates as is should [ one way extension after winding it up] yet the tensioner is almost at the very end of its extended position against the guide. Is this indicative of a loose chain or considered normal wear and range of operation? Cam timing / valves all check out. Do these chains actually stretch given there just driving a small cam? Thanks to all for any recommendations!

 

[retro]

Yes, you've got it figured out correctly. Once the chain tensioner nears the end of its extension range, the chain must be replaced. If you run them too long the chain will jump time (climb over teeth on the sprocket) and the motor will quit running, possibly bending a valve (piston smacks an open valve) if it jumps more than one tooth.

You can find a link to a copy of the service manual at the top of the manuals & schematics section:

https://www.hondaatvforums.net/forums/forumdisplay.php?f=32

Welcome back to the forums!

 

[monza4me]

Thanks to all for the helpful suggestions. Indeed the stock factory chain of 31 years was stretched....and the valve stem seals dry/hard. Both easy to change out and now with accurate cam timing, runs great, onward for many more years

 

[retro]

Thanks for following up and letting us know how you fixed it!