Ktm 125sx

[AustinGrady]

Hey guys i have a 2007 ktm 125 its has low compression after i just put new rings and gaskets on it...also it will not start sounds like it wants to but it doesn't have any ideas. thanks for any help in advance.

[tye1138]

What did the cylinder look like before the build? How about the head gaskets, are they brand new?

[JoeMcLaughlin]

A lot of variables to look into. So the bike was OK on compression and you did a top end job but now it is low? A little more detail would help narrow things down. What piston kit did you use? Verify you have the piston pointing the right direction, arrow pointing to the exhaust port. Verify rings are installed right, Vertex letter is up. Make sure you torqued the base nut to the cylinder down. There are a few basics to check out.

Joe.........

[AustinGrady]

Cylinder look amazing and bought new gaskets for it before I put it back together

[AustinGrady]

Ok thanks joe I will get on it and see what's up and I'm getting a new piston sent to me when I retear it back down ill check and send pictures

[bikedad1]

All what those guys say, plus did you measure ring end gap, piston to cylinder clearance, cylinder out of round and all the points that your manual tells you to measure within the . cylinder. Cylinders typically wear most at the top of the stroke since that's where all the energy is expended. Kinda like an ice cream cone shape in thousands of an inch. what were your compression numbers?

[AustinGrady]

Sorry for not replying in a while but i could not do a compression test because i dont have gauge..but i think that fuel is not getting to the piston

[AustinGrady]

also it has low compression but i just put new rings on so...

[AustinGrady]

also it rolls in gear

[bikedad1]

got spark and are timming marks lined up. are reeds in good condtion? Nothing missing? Last guy missed two screws holding the reeds in place. Would not start. was in the carb half a dozen times! Then check that gas comes out of fuel line to carb, then tip bike way over and see if gas comes out of the over flow. Use an open flame to make sure its gas and not water (joking) LOL. Those are simple tests (less checking the reeds). if these fail, dive into the carb. THis would be what I would do, but then again I've made my fair share of mistakes!