Help!! 03 kx 125

[kingsolver22]

Im a newbie, ive rode my bike for about 8 weeks, it had a new top end on it when i bought it. I was riding yesterday, and everything was fine i was cruising around the track when my bike suddenly lost power. I was still going but my throttle wasnt really giving me anything it was slowly sputtering to a hault and fast. In about a half lap it went from bad to worse and totally stopped and now i cant get it to start. Can someone help. Not spark plug. Thanks. Ive cleaned the air filter regularly and changed the gear oil regularly.

[FPMXer]

Gas???? If there is fuel do a compression check it should have around 125psi or more. If it's below 100psi you need another new top end.

[crf150R]

sounds like its about to seize

[bigbluerider4life]

how do you know its not the plug? its sounds exactly like you fouled a plug and need a new one

it wouldn't hurt to take it to a dealer or local shop and have it comp tested either

[kx_rider53]

Does the kickstarter have much resistance? How does the plug look?

[4strokes4me]

How do you know it had a new top end? What all was replaced? Just wondering if you are the umpteenth guy to buy a bike with a SUPPOSEDLY new top end.

Have you changed the spark plug out with a new one?

[kingsolver22]

okay the kickstater does not have much resistance to it. I noticed this too but i dont know the significance of it please help. When i first started the day kick stand had lots of resistance and now hardly none. I put a new plug in it, not that. I do appreciate the help guys, sucks to know nothing about something you love to do. Im learning though, thanks

[baldys]

hi

the say thing happened to my kx 80 i just did a top end rebulid and just finished running it in and it sized coz it put to much pressure on the bottom end bearing, just wondering can you even kick it or is the kick starter stuck?

but now ive got a kx 125 and did a full end https://www.thumpertalk.com/forum/newreply.php?do=newreply&p=3863361&noquote=1#

https://www.thumpertalk.com/forum/newreply.php?do=newreply&p=3863361&noquote=1#

[kingsolver22]

yes i can kick the bike, it just has very little resistance. I believe this has to do with no compression from the reading ive been doing. Im putting a new top end in it next week, im hoping thats all it is.

[bikepilot1]

Yep, sounds like something bad happend to the top end. If its really easy to kick it doesn't have much compression. You can buy a compression tester at sears or most car parts/tools places. Its worth having one around (they aren't expensive).

Did the bike have proper oil mix in the fuel for sure?

Its not normal for bikes to loose compression quickly like that. Usually when they do its from either sucking in dirt (perhaps the filter was torn or the carb boot loose or something) or insufficent oil mix.

I'd check the compression and if its low, which from the sounds of things it will be, I would pull down the top end. It should be pretty obvious why it lost compression at that point, then you can both fix the problem that caused the loss of compression and the actual compression issue itself (probably piston and rings will do the trick, but the cylinder might be damaged).

good luck

[kx_rider53]

Def. sounds like the top end. I would open it up and see what happened.