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After tearing down the top end of my 2000 KDX 200 (bought used) it appears as though the top end on this bike has been done exactly never. The cylinder needs some work, but my biggest concern is what looks like a chip in the plating that is missing on the intake side, on one of the narrow vertical sections. See the attached pic.



I’m used to wrenching on jetski engines and I’m not too familiar with plated cylinders. How difficult (read that, expensive & time consuming) is something like this to repair? Do you have to re-sleeve or just overbore?

My list of needed maintenance gets considerably longer the more I tear into this beast…

EDIT:...can't seem to get that HTML tag to work for the pic...

I fixed it!~

Yup... that's a chip.... and will continue to keep chipping more than likely until you get a replate job done. Kinda sucks since it's riding season... If it was me... I'd proly run some scotch-brite on it and run it til Winter.

I agree with Vince. Since the chip is not in the upper part of the cylinder, it will have no effect on engine compression. Not to say your rings are in good shape though, this chip should be o.k. if you clean that thing up a bit.

Thanks, that's good to hear. I'm going to replace the piston and rings, gaskets, etc. The rest of the bore seems OK, a little scoring, but nothing that will catch a fingernail except that chip.

I'm taking apart and cleaning the KIPS now...holy cow...

what does the piston look like on the intake side? post some pics of it.

Based on my results of a re-plate I, too, would leave it alone.

The junk on the top is more likely carbon and or aluminum. I wouldn't worry a whole lot about it.

Re: Do you have to re-sleeve or just overbore

The general method of repair is to bore and replate. You could use a sleeve if you wished..but I don't know why you would want to. Be careful if you replate. My experience with USChrome (Wisconsin, I believe) was bad. I have to 'repair' the 'fix' sometime. I'm not the only rider with lousy results from USChrome. I don't care if E.Gorr recommends them or not. ...maybe he has never used the Wisconsin outfit?

Be sure to send your replacement piston in WITH the cylinder if/when you go the replate route. After replating, the cylinder must be diamond-honed to clearance-fit your piston.

A replate job runs $150-200 thereabouts. Of course, considering all the other stuff that goes with it's not a huge deal. Big enough!!

Chip in the cylinder? Again a member of our club have to deal with this like you...

this is a 220 2001

Wow…I guess I should feel fortunate about my chip!

I didn’t take a picture, but the intake side of my piston is grooved out a bit, so some of that probably is aluminum on the bore, as CC mentioned. I’m going to replace the piston and rings and clean up the cylinder with Scotch-Brite as best I can, then run it for the summer.

A couple of things:

A cylinder problem in a 220 isn't the same as one in a 200.

Now...THERE'S some rocket scientifical comment, 'eh?

The point is...220s have OEM piston problems. That a 220 has a plating failure may well relate to the known PISTON disasters..not necessarily to the cylinder itself.

The 200 does not have the same or similar piston problems. A plating failure in a 200 came from something else.

KDXQ's pics are quite evidently of a simple plating failure. It started on the edge of a port..and it can be lifted with ballpoint pen fer crine out loud! Somebody severely screwed this thing up.

Teee's is also at the edge of a port..but from all the aluminum stuck on the wall, you know it's an apples an oranges thing (the two cylinders). Besides being in 'opposite' areas on both axis, even!

Muriatic acid will take that aluminum off. Obviously...the 'acid' part of that solution is something to take care with.

You're familiar with the alpha piston groupings of OEM pistons? Your cylinder and head will be marked with A,B,C,D,E,F,G.

...aw...never mind. Let's start with the question first.

A BTW...but an intake seizure is commonly a lubrication failure...and things related to that.

Thanks CC. My wrenching experience is with 2-stroke standup jet skis, so I understand the merits of adequate bore to piston clearance (and have first-hand experience on what happens when you don’t have enough)...and also the difference between forged and cast pistons, etc.

That being said, plated cylinders are new to me. BUT...I have read the threads on the alphabetic piston groupings, although I haven’t checked to see what my cylinder is marked. Too much time at work, not enough time for wrenching and riding.

About what lead to the problem...I think it happened before I bought the bike. It’s behaved about the same in the year and a half or so that I’ve had it. I really haven’t put that many miles on it so I’m still getting my feet wet. I’ve been running premium pump gas with Dumonde Tech Z1 at 40:1.

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kdxquebec wrote:Chip in the cylinder? Again a member of our club have to deal with this like you...

this is a 220 2001

There's your problem! You had a telephone in your lower end!~

The differences are very small. Still something to be aware of.

If I had an 'A' cylinder, I'd be pretty squeamish about sticking a Wiseco in it.

kdq: That IS a cool pic. I don't think that cylinder was plated...I think it was painted!!

Indawoods wrote "There's your problem! You had a telephone in your lower end!~ " Yep - had it been a digital camera phone there would not have been any problems with that damn cylinder.

Concerning the picture - I did not realize the stock plating was anything close to being that thick!! I thought it was like 3-4 thousands of an inch. Everyday is new day to learn something.

I think a worn "A" cylinder would hold a Wiseco fine.
A new "A" would be a different story though....

Has anyone ever seen a "A" KDX cylinder? Not me.....

Yeah, that'd be tight and would require a full-warm up for sure!

IS it stock plating?

Yes it is the original plating. I just got a reply from him.

No, this doesn't necessarily apply to electrofusion or anyone else's plating, but Langcourt says they can plate to hundreds of thousandths.

Hopefully it would 'stick' better than the 'phone job' cylinder.

LOL the phone job cylinder ... gess we will remember of this one!

It's like a new bike!

Finally got everything back together. I cleaned up the aluminum on the plating with some acid, then hit it with the Scotchbrite. New piston, freshly cleaned KIPS, etc. You can lift the front end with a twist of the grip...just like a real dirtbike.

Thanks to all for the advice!