yz125 compression...

tyler_43

Member
Jun 22, 2007
126
0
Did a compression test on my 2002 yz125
first compression test cold (6 degrees outside... in that weird temperature you southerners use it's 43) and got 136 (I hadn't run the bike in 2 weeks so maybe there wasn't much enough gas around to provide a good seal?)

second test i fired up the bike just until the rads started getting warm... shut it off, let it cool down for 10 mins, and then tested it. I got 150 that time...


does that sound bad? I've heard 160-170 from different people...
 

BigRedAF

Member
Jan 9, 2005
739
0
That's a bit low for a warm bike. The current crop of two stroke power valve bikes generally put out around 185 psi. Don't be worried, a new ring or piston and ring set will most likely solve your issues.
 

Ron2stroke1

Member
Feb 28, 2008
41
0
I ran my yz125 till it dropped to 105 psi and it still ran great. Started right up, and had alot of power.
 

BigRedAF

Member
Jan 9, 2005
739
0
Ron2stroke1 said:
I ran my yz125 till it dropped to 105 psi and it still ran great. Started right up, and had alot of power.

Runs great is a relative term, compared to what?
 
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