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Well it finally happened...........and at the worst time. I had went to the annual Loretta Lynns spring ride this weekend and was 2 miles into the trail on Friday the first day of 3 and stuck a piston. I hadn't changed anything except adding an IMS tank. I had ridden many times this winter with my new Air Striker setup and all was fine. I noticed immediately the bike wasn't as crisp as usual but still was running pretty good but down on power. Then she quit. Of course I had 5 hard years on my stock top end. Maybe it just finally got tired. It is still stuck though. Any ideas on how to get cylinder off with it stuck? I'm not sure what happend..........hadn't tore it down yet. Is it time for a 225? ProX or Wiseco? Hmmm...........all I know is it ain't gonna be cheap. I'll let you know what I find.

fulltiltboogie wrote:Well it finally happened...........and at the worst time. I had went to the annual Loretta Lynns spring ride this weekend and was 2 miles into the trail on Friday the first day of 3 and stuck a piston. I hadn't changed anything except adding an IMS tank. I had ridden many times this winter with my new Air Striker setup and all was fine. I noticed immediately the bike wasn't as crisp as usual but still was running pretty good but down on power. Then she quit. Of course I had 5 hard years on my stock top end. Maybe it just finally got tired. It is still stuck though. Any ideas on how to get cylinder off with it stuck? I'm not sure what happend..........hadn't tore it down yet. Is it time for a 225? ProX or Wiseco? Hmmm...........all I know is it ain't gonna be cheap. I'll let you know what I find.

I dont have a KDX yet, but I stayed at a Holiday inn express last night.

These guys can help more than I can but something you said light a bulb over my head. You say you changed to a new tank. Unless my memory is fading, usualy a siezure is caused my running too lean, and that can be caused by an air leak. Im not sure how a new tank would cause an air leak, but thats the first thing that popped into my head.

Back in the day, I would pull the plug everyday I rode. Run about 10 minutes and check for color. If its a coco brown, your jetting should be about right. If its a light to white color, your too lean. Black and greasy, too rich.

You could of also broke a ring. If you did, that can be expensive.

But if you got 5 hard years out of that top end without ever tearing it down, you just made me a Kawasaki KDX fan. LOL Sorry to laugh, I realize its not funny to you, but I think its time for a rebuild anyway. If it were me, I would rebuild the lower end while I was at it. Its possible you may have to tear it all the way down to get the piston out of the barrel anyway. Crank seals, bearings etc.

Like I said before, I really dont know anything about the KDX. I could be wrong about a few things and Im sure the guys that really know their stuff and correct me. Thats a good way for me to learn also.

Try this for now. Pull the plug. Make a mixture of 50/50 Marvells Mystery Oil, and ATF. Put in 3-4 cc's on top on the piston and let it soak for a day or two. It might break loose. I race RC cars and that sometimes works on our Nitro motors that seize.

Good luck!

Seen it done on seized engine by taking top off and pouring some boiling oil in the barrel, may end up with 3rd degree burns, or it might work!

I bet RB has seen and fixed a few...hundred seizures.

Penetrating oil around the piston with the head off - let it sit for 4-8 hours - then tap the top of the piston.

I've use a hammer with large diameter block of wood on top of the piston and then tap the wood block with a hammer. If the engine is "out" then the wood handle of the hammer can be used directly to tap on the top of the piston. Of course it depends on where the piston is siezed on the barrel but sometime you need to remove the cylinder bolts and lift up the cylinder (and block-up the base of the cylinder) so the piston has some place to go. Don't get too carried away with the strength of the "taps": you do not want to damage the rod or the crankshaft. Good Luck

Well I took the head off to see the carnage. Some metal pieces but not a bunch. The damage I can see is right above exhaust port. I did get the piston to move down with a few taps but it still will not come up past the exhaust port. Broken ring? I dunno.... I just won't know until I get the cylinder off.

Sounds like the ring end gap caused it to snag on the port, but heck what do I know.

Got any pics FTB?

My guess is a broken ring....

Just try and remove the cylinder ......, no need to make the piston go all the way up and then down. Just try and slide the cylinder off the piston!

It could be a crankshaft problem, or a broken piston skirt that is keeping you from turning the engine over a full rotation.

Ron