'03 YZ85 compression check

[deadhead]

Folks,

What psi range am I looking for when I check the compression on an '03 YZ85? I can't find the numbers in the owner's manual.

Thanks,

Tony

 

[DKM Factory]

Usually the bikes I work on are 160+ with a fresh top end, if 150- time for rings or a top end kit

 

[deadhead]

Thanks much.

deadhead

 

[Jasle]

what I do is check the compression when it has a new topend...then recheck it periodically and when it gets below 90% of the original value then i do rings and check the piston. I have found that different gauges give radically different readins. I have seen one say 150 and the other say 115 on the same motor within 5 minutes of each other.

Also make sure your checking with the throttle wide open

 

[poffracing]

I just put a top end in my son's '04 YZ85 last week. I checked compression last night and it was at 155lbs. Hope this helps.

 

[deadhead]

Jasle,

I agree with your approach. Unfortunately, I only recently purchased my compression tester. Had to have one.

The owner's manual for my son's old KX65 gave a psi range. I think it was 155 to 171 psi. I can't find one in the YZ85 manual.

deadhead

 

[Jasle]

well keep in mind for next time.