Bog and idle surging kx125

Just pickEd up a kx125 not running for $700. It had a wire broke of the magneto. Solder it back on started first kick. After the bikevent warms up and you Crack the throttle the idle with start surging (climbing and lowering) but if I turn the idle screw down just a take it doesn't really want to idle. With my experience racing Jr dragster I want to say it's lean on the idle circuit? Or is it different with these 2 strokes.

Also once you hit full throttle before it hits it's highest Rev it bogs. Is this a lean issue or you do you think it could possibly be my half a$$ fix to the magneto to get through bike running.

Sounds like a bunch of lean issues.  Make sure you don't have an air leak somewhere.

Sounds like bad crank seals. You should do a pressure test to check those, or just assume they are ancient and replace them. There are other air leak sources also, though.

Afterwards, you should check compression (I would just assume the top end is old and replace it), reeds, and silencer packing before swapping brass in the carb. I would imagine you have already cleaned and lightly oiled the airfilter.

Top end is good. Compression checked it before I bought it last Monday and it was right around 175psi. Crank seals could be bad. I pulled the carb off and did realize the carb boot was pretty cracked and dry rotted so new carb boot and I have some jets around I may throw in to waste time.

I am going to do and full bottom top end on this just have to find time. Pretty clean bike but I wanna rebuild it and go over it and fix all the stupid little things and bring it up to my standards.

Sounds like you have a good plan! Congrats on the new ride. What year is it?

2000. It's pretty clean. But I wanna rebuild the motor so I know it's done right. Rebuild shocks and forks. Powder coat the frame new plastics new bearings all around the typical make it a "brand new" 2000 haha. Paying $700 for it only I really don't mind putting a lot into it.

Yeah, sounds like you'll have a pretty sweet ride for not a lot of cash. Good luck with the build!

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