Transmission problems 2004 KX125

You bike is possessed! Call a Priest now!

its 7 years old, get a new 250f!

Pull the clutch cover off and inspect the clutch plates and then the basket, then in the shift mechanism check the flapper along with the pin and spring.

The drain plug bolt is stretched. Get a new bolt and washer, in fact buy a couple bolts so you have a spare. The bolts stretch as you reuse them several times. on the kx 125 the bolt threads in directly below the shift drum. It is a very close fit even with a new bolt and as the bolt stretches slightly it rubs on the shift drum.

Motofab36. I'm impressed. I've been a mechanic for years,and I always say ,the first thing to do when diagnosing a problem is to try the easiest thing first. Just to eliminate it before digging in deeper. But I never would have thought of that in a million years.The other thing I say is that there is no better thing than experience.If you're right about that bolt,you just saved that gentleman countless hours of aggravation ,and expense. With your permission,(if you will), I'm just going to add one thing. Change your oil,throw another washer or 2 on the bolt and tighten it. If it drips a little don't worry about it. Go ride it,and see if the shifting is good. That will tell you if the bolt is causing a problem. I never had Kawi's but I have experienced the same problem with bolts that motofab36 has on Yamaha's,but in different areas.I still don't understand how it happens. A steel bolt threading into an aluminum casting,and the bolt has the failure,not the casting. I've had it happen on every Yamaha 4 stroke we had. Maybe someone can explain it to me.

LOL, I learned the hard way. I had a customer bring in a kx 125 with the same problem. After looking at everything else, even splitting the cases a couple times I saw what the problem was. Sometimes its easy to look past the simple things. I've seen several stretched drain bolts. You'll see it just below the head of the bolt.

If motofab's suggestion ends up fixing it, he deserves a case of beer or something.

Well did that fix it? If so, Coors Light please

Brilliant my mates 04 kx 125 had this problem after changing the oil

It would not click into gear and felt jammed after reading this we went and loosened the oil drain bolt and bam it went straight into gear

Brilliant thanks

Had the same problem , use 2 drain plug washers, or grind a little bit of of the drain plug.

So does it work ? Lol my 2004 is doing the same it dident want to shift out of second gear then finally got it to shift and worked great ?

Had the same thing happen. I bet this is the fix! Who knew it would be so easy lol. I sure didn't. When I compared my stretched one to the new one it was significantly longer.

Best thread I've read in months. Thanks!

You beat me to it, was going to suggest the same thing!! I also see now this is a very old thread!

So it works lol ?

Hey I have a similar problem where I can shift to first but won't go up into second can only go back and forth between first and neutral kx125 2001