so i was wondering how much compression is considered to be a decent top end for a 02 cr250?
150+ should be fine anything below that would be low
MY 97 had 180 cold with the old top end and stock piston. i just put in a prolite piston and i am getting 170 cold befor having run the bike. It wll be interisting to see what it is after i break it in and thry it warm.
Why change it?
I have had my bike for 4 years and never touched the top end. If i was going to take it off, i was going to replace it. i measured the piston, and the diameter and ring grooves were right at the wear limits.
I was at 195: Fresh piston and rings, cold, with base cut and head/squish set up for race fuel on an 02.
FYI on my 97 above where i got 170 with the new piston i checked and the squish was at .065". After i break it in and see how it runs i will pull the head and cut it for a squish of about .045 - .050 and then see ow that runs.
Update on the 97 with the new top end. After one heat cycle and with the motor still warm i got 190 PSI.
ok so i checked my compression, it came to 195 cold, i havent tried it warm yet. the bike supposedly had less than 20 hours on it, but im just glad the top end is looking good.
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