1985 XR80 compression ????

[HondaBrat]

Does anybody know the normal range for compression on these motors.. This one I'm working on has 135 psi warm. I have to pull it back apart because I forgot to stagger the rings 180 degrees from each other and now it smokes like a freight train with new valve seals.:bang: I split the case to do a timing chain.

Thanks,
Michael

 

[HondaBrat]

76 views and nothing WOW

 

[Ol'89r]

76 views and nothing WOW

Sorry nobody has answered your question yet HondaBrat. I'll give it try. That engine in good condition should have 150 to 160 PSI compression. When you check your compression, be sure to hold your throttle wide open. Also make sure your rings are in correctly. Many rings are tapered. There is a top and bottom to the rings and there is usually a marking on top. If you put them in upside down they become an oil pump instead of a compression ring. You may have low compression with new rings until the rings get a chance to break in to the cylinder. If you add a little oil to the cylinder and the compression goes up, that means your new rings have not seated in yet. If the compression does not go up, your valves may not be seating properly. Good luck.:cool:

 

[HondaBrat]

Thanks ol'89r. I put new rings in it . Top compression ring had a .025 end gap ( junk ) and the 2nd ring was at least double that. Runs like a champ now.