Compression

[Judge]

Just wondering if someone can tell me wat sort of compression should a140cc lifan i think it is, I m going to do a compression test on it I'd just like to know wat it should be

 

[my67xr]

how old/how many km's on the engine ?
it should have around 150 - 180 psi iirc

 

[Judge]

Not to sure how old it is I got the bike given to me an I'm trying to get it going but it just DONT seem to have much compression

 

[my67xr]

have you adjusted the valves yet ?

as they wear, the valve clearances get smaller, and eventually they don't seal off in the valve seats
this makes them hard to start, and can burn them out too if left like it

set them to .003" for the intake, and .004" for the exhaust
this video will show you how to do it.

[video=youtube;QJciyJRJh8Q]http://www.youtube.com/watch?v=QJciyJRJh8Q[/video]

 

[my67xr]

i was thinking about you checking the compression last night.
what compression tester do you have ?

if it is the rubber boot type, it wont be 100% accurate, they can easily leak, so your reading could be 10-15% lower.


a screw in one would be the most accurate, but i don't think they are readily available.
but i could make one for you if you need it ?

 

[rotn50]

Yeah the rubber ended ones are a bugger, its a two man job with them and need to do it a few times to get an average, hold the throttle wide open also when testing. Anything under 100 psi after valve adjustment basically wont run at all or if it does its not rideable.