KDXRIDER.NET

Hello everyone.

Just wondering if anyone had any knowledge on the proper appropriate cylinder clearance for a KDX200.

My H-series service manual states 0.079-0.089mm clearance (approx 3.1-3.5 thou). Going on to say that if it is below that, it should NOT be fitted as it may cause seizure, but slightly above is OK.

However the Wossner piston that just arrived at my door states 0.06mm (2.4 thou). According to Kawasaki, this can cause seizure?

My clearance was with the B size Wossner is around 0.11mm (4.3 thou) which is a bit to big. So I'm going to send it back for a Pro-X as they make sizes A-F so that should easily close up my clearance issues, I just don't know whether to aim for 0.08 or 0.06.

Piston clearence is built into the piston not cylinder. If going forged you will see more clearence. The 2.4 is Min. piston clearence for builders that run them tight. Forged pistons expand quite a bit.

A factory piston is Cast so min. expantion. For this reason they can be run tight.

I would go with the Wossner. If you are @ .0043 cold your piston will expand most likly to around .0015-.002. For this reason it is Very important to warm up a forged piston engine before high load.

Hope this helps

The piston you took out should or may have a letter stamped on it ..either A, B etc...just replace like for like ..I fitted a `B` size wossner in my 220 ..top quality piston & very well made...are you sure the measurement was for the piston & not the ring gap ??... a `B` size should be fine provided you haven't had a re-plated cylinder recently.

Ohh ok. Thanks for the info!

Old piston is the oem piston, cylinder has never been replated, so would have seen 5700km's. And replating here in Australia is about the price of a brand new cylinder from Kawasaki.

Yeah, ring gap is within spec.

ABCDEF are nearly immeasurable in difference....Like .0002mm not inches. They stamp the cyl, and your supposed to just get the next size up on rebuild...because no common garage tools can measure the literally microns amount of plating that wore off during the period of service. They aren't like .010 oversize type deals. A Wiseco is like an F, and can be used in any cylinder...however, if the cyl was an "A" in size it will be tighter, but again all within range for clearance. You could put an A in an F cylinder and it would be on the loose side, but still within range for clearance. Warm up for tight clearance, and due to forged piston.

ProX go up by 0.1mm. My Wossner B is 65.95, a ProX F is 65.99. So I just thought using that I could get the clearance back down which has to be better? Would drop from 0.11 to 0.7 clearance.
I thought if clearance was too big the piston skirts can catch on ports?

Thanks for all the info again!

Got clearance checked with a micrometer and it is similar to what I thought with feeler gauges. I'm going to run it though, it's nothing crazy and I've talked to a few mechanics that say it shouldn't be a massive problem, just next rebuild I'll get a sleeve or a replate :)