Compression Question for YZ125

Joined
Aug 31, 2006
Messages
12
Likes
0
#1
Hello,

Can anyone tell me what the compression should be for a 2001 YZ125? Also, any tips on replacing the top end?

thanks in advanced.....
 
Joined
Oct 3, 2006
Messages
40
Likes
0
#2
Not sure if it is the same because I have an 05 but mine was 165psi just after break-in on the new bike. Hope this helps. And most say to replace the top end after a 10-12% drop.
 

kawicam250

I bleed green!
Member
Joined
Aug 7, 2006
Messages
1,162
Likes
0
#3
burgunder said:
Not sure if it is the same because I have an 05 but mine was 165psi just after break-in on the new bike. Hope this helps. And most say to replace the top end after a 10-12% drop.



thats probably because the engine was almost brand new, my 00' KX125 has about 96 PSI when i replaced the top end. so i wouldnt worry if you have more than 110-115 PSI :nod: .
 
Joined
Sep 12, 2006
Messages
329
Likes
1
#4
I don't know how the 125's compare to the little KX100, but I normally see around 165psi on my son's KX85 & KX100 top ends.
 
Joined
Apr 8, 2007
Messages
292
Likes
0
#5
kawicam250 said:
thats probably because the engine was almost brand new, my 00' KX125 has about 96 PSI when i replaced the top end. so i wouldnt worry if you have more than 110-115 PSI :nod: .
i dont think it matters if the engine was new......
i have a 1984 cr125 and after a new top end i get 180PSI.

You should be getting around 160PSI to 180PSI for a good running top end. if you have anything lower than 130PSI its most likely time for a new topend.
 
Joined
Mar 30, 2006
Messages
341
Likes
0
#6
96 PSI is quite low. My old RM125 put out 165 PSI it should be in that range. Do a search too on this subject youll find lots of info.