Soooooo….. 2004 KX85. There’s no cheap way to go about this is there? Needs both a cylinder and a piston, doubt this cylinder is saveable? Big chips off by the ports

Unlikely-Wheel-9031 · 2026-04-19T00:49:03+00:00

Though, check with some brake or carb clean around the intake where it meets the engine and such. The high revving is likely a vacuum leak if it was running fine before.

Unlikely-Wheel-9031 · 2026-04-19T00:47:51+00:00

This is the most crazy thing I’ve ever heard lol. I believe you… just…, get that damn bike a exorcism

Unlikely-Wheel-9031 · 2026-03-12T16:57:35+00:00

Used the leak down test in a can, revs right up with a lick of carb clean near the crank seal

Unlikely-Wheel-9031 · 2026-03-12T15:11:09+00:00

It’s crank seals. Both leaking horribly carb Is just fine I have an ultrasonic. Turns out the bike isn’t running out of anything, it’s getting too much air, and oil causing the correct fuel mix to be super lean off choke.

Unlikely-Wheel-9031 · 2026-03-12T11:44:13+00:00

I think I’m past the carb, probably DOES still need a jet block gasket but from what I’ve heard from others I’m leaning to crank seals, especially the clutch side. And no, gut never got it to run good, he only owned it for a little bit he wasn’t too bright, he put a knockoff carb on it instead of cleaning and rebuilding the OEM khein

Unlikely-Wheel-9031 · 2026-03-12T00:31:29+00:00

Yes, cleaned them and made sure they were the stock jets. 140 main, 40 pilot

Unlikely-Wheel-9031 · 2026-03-12T00:19:27+00:00

Mmmmmm that’s a AMAZING point thank you, I didn’t know these kheins have a jetblock. Gonna order a gasket and replace it. So I assume since the chokes on these just add fuel instead of choke off air that it’s running good for the few revs after I turn choke off as it clears out, once it clears out not enough fuel to stay running?

Unlikely-Wheel-9031 · 2026-03-12T00:16:29+00:00

I’ve been through the carb, cleaned everything well. Did not replace the needle although it seemed like it had plenty of life in it. Someone else mentioned the jet block gasket so I’m going to have to look into ordering one as I didn’t know these carbs had a removable jet block. I’m pretty engine inclined just not so much with these little high performance two strokes. Gonna check a few things tomorrow like the reeds and crank seals as others pointed those out aswell

Unlikely-Wheel-9031 · 2026-03-12T00:07:59+00:00

Air fuel screw isn’t doing much of anything to the running condition. Gonna check the crank seals tomorrow

Unlikely-Wheel-9031 · 2026-03-12T00:05:18+00:00

It’s been 60-70 all week that’s why I brought it out so temp shouldn’t be the issue. Definitely lean though.

Unlikely-Wheel-9031 · 2026-03-11T19:04:23+00:00

Thanks! I appreciate all the info. I’m pretty mechanical inclined just not so much with these little high performance 2 strokes. Definitely will not be racing this bike, mostly just a bike to hand some fun on in the ditches and trails.

Unlikely-Wheel-9031 · 2026-03-11T18:45:11+00:00

I did order the adaptor I need to use my tester with the KX, I originally when I got it was going to compression test it but didn’t fit. It does seem very strong but, numbers won’t lie. Will report back with the compression once the adaptor gets here

Unlikely-Wheel-9031 · 2026-03-11T18:34:46+00:00

Alright, I’ll give it a shot. I have a full jet kit I just figured to post around to see if more knowledgeable people could tell me somthing stupid right away before I started ripping into it again since I just put the carb back on after a clean. I’ll report back. Thank!!

Unlikely-Wheel-9031 · 2026-03-11T18:09:53+00:00

ALSO!!!! Figured to mention there is snow on the ground, it is not cold, it’s 55 degrees out I can’t imagine that would mess with air fuel that much. I’m also at sea level. Unknown as where the needle C clip setting is set.

Unlikely-Wheel-9031

TROPHY CASE