Please Help

[Thug]

I have a 1985 KDX 200. I was riding one day. The bike just locked up. Someone told me that I had to clean my top end and replace the rings. But someone else told me I had to replace everything. Can I just replace the rings. And Ride Again.

[TimSr]

If it locked up, I doubt youll get away with replacing rings. Either way, youll need to take the open end off and check it out. Also most of the Kaws from that time period used an unboreable electrofused cylinder which means either replace the cylinder or get it resleeved, with either choice being quite expensive.

[Macs]

you most likely chewed up the cylinder. i would check on getting it resleeved. sometimes you can find places to do it at a reasonable cost (well not as cheap as boring but cheaper then buying a new cylinder)

[Captainuno]

Like the previous post both stated, if it locked up hard, you will probably have to replaced the piston & rings, however the cylinder may still be able to be saved, it just depends. Take it a part and use muratic acid to remove the siezed aluminum from the bore, then check and see if there are any gouges or deep grooves in the bore, if there are none, the cylinder will be ok to use as is with the new parts. If the cyl is damaged, then like the previous post both stated, either bore it and resleeve it or have it rechromed.
I had an 83 & 85 KX's with chrome bores, siezed them both 2 times and never had to buy a new cyl. Those barrels are very hard and don't damage that easy.

Kirk

[Tri-Z Pilot]

How do you know that the bottom end didnt lock up?

[NOS_350X]

you take off the head then try to get the jug/barrel off it it come off easy then its not your topend (you want it to be). after that if you can move your rod back and fourth then its not the rod berring. if the just just dosent come off then its your piston.

[Captainuno]

Easiest way to check is to pull the exhaust and take a peek at the piston. 95% of the time the piston seizes on the exhaust port side of the piston. The powervalve (KIPS) on those older Kaws are on the side of the exhaust port so you still have a clear view of the piston.

[const42]

the 85 never had a kips power valve but hey if it is the lower half I have 1 with a good rod I would guess your crank end bearings went out on you man let me know it will be far cheaper to buy a lower half than to rebuild it but our shop can do that also e-mail me @ chancelor@scgdirect.com thx we also have a topend if that is bad.

[Captainuno]

I really wasn't sure if the KDX200 had a power valve or not, I was talking about my own experience with my 85 KX125 which does have a KIPS, the point I was trying to make was if it did, they were mounted on the side of the main exhaust port, not in the middle and that you could still see the piston clearly. Sorry for the confusion.

Kirk

[const42]

aww hey no problem man no harm you are correct with the kx motor