top end

[brodie filipek]

Need help fast! ( top end rebuild )

i have a ktm 125sx 2001 model. i just bought it last year in november fully rebuilt and i have road it around alot and i think it needs a top end rebuild. How do i tell if it needs one or not?

 

[xkevenx]

feel your compression, if you feel it lacks then you should change it, and you could check your piston itself, for scratshes and stuff thats the only way, just open it up!

 

[Coop]

A compression test is your best bet. Get a tester, screw it in the spark plug socket, hold the kill switch, open the throttle and kick until the gage stops moving. A 125 should have approx. between 150-190 psi.

 

[Clint3240]

quick way is to puch the bike in gear or hold your thumb over the spark hole and if it blows off you could be ok.

 

[IndyMX]

quick way is to puch the bike in gear or hold your thumb over the spark hole and if it blows off you could be ok.

Errr.. No it's not.

That will tell you absolutely nothing.

 

[griffbones]

The compression tester is the only way to really find out how much compression the engine has. Even a compression test will not tell you the story on the top end. There can be wear present, but that doesn't always mean that the compression will be low. Sometimes routine maintenance and a visual inspection is the only real way to tell what shape things are in. IMHO

 

[brodie filipek]

thanks guys for your help

cheers!!

 

[brodie filipek]

my mates always say after 30 hours your bike is due for a top end rebuild. Is that true?

 

[RM85rider123]

my mates always say after 30 hours your bike is due for a top end rebuild. Is that true?

it depends how you ride. if you race, maybe every 12-15 hours. for trail riding, it depends.