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[img][/img[IMG]http://i1149.photobucket.com/albums/o593/98rebuild/DF42FC7F-8BCF-4014-8CF4-618BCEA74579_zpsbkpuzyyh.jpg[/img]]

Trying to figure out posting pics. This is just one. I have more but just making sure this works first. It's a 98 kdx200

Ok. It looks like the link is working so....
Hi everyone! Love this place. This is my first post. So, I'm doing a frame up build on this 98 kdx200. The bike was in rough shape but started good. Needed almost everything. So that's what I'm doing. The only thing I don't want to do is send my cylinder out if I don't have to. I can't afford it right now considering I'm almost in this for $1500 already. I have no history on this bike at all. I cleaned the piston off to see if it was stock. I think it is. One ring is right at the service limit and one is just under the service limit. Doing a new piston obviously but my question is do you guys think the rings are worn or the cylinder. I can't bring it anywhere to get checked. So how does this cylinder look?? Please keep in mind the lighting in the pics. There are no scratches, nothing I can feel with my fingernails. Right at the top there is a slight edge but not much at all. Can I slap a piston in and rip!!!!?

Can you measure the bore?
If not I'd probably put in a new piston, rings, top bearing and clips, reassemble and check compression. If good, ride it! Oh, check the ring end gap before assembly.

No I can't check the bore. I wish I could. I just hope when I check the end gap with new rings it's in spec.
I'm hoping the rings are just worn out. If I absolutely have to I'll send it in. Just trying to see what some people think of the condition of the bore. I think it looks ok but there are people here with more experience then me. I do plan to check compression. Thank you. I appreciate the response. I would love more opinions guys and gals.

Can't see your pic. Try any image hosting other than photobucket. Imgur, Flickr, etc.

here ya go

That last one does not look good to me.

That looks like it needs to be replated badly IMO.

I agree, replate.


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" I can't afford it right now considering I'm almost in this for $1500 already."

May I ask what other repairs or modifications you had previously made? Thank you.

Sure. I personally haven't done any mods to the bike. The reason it's getting expensive is because it needs a lot of parts. Bearings, kick shaft, kick spring, kick lever, tires, bars. The list goes on and on. But it ran good. There is no scratching or gouging. Nothing you can feel anyway. The mods it had when I got it. The air box lid has holes drilled and it has a full FMF system. That's it. Stock jetting was in it. Like I said the rings are right at the service limit. Just under actually. So I'm hoping with the new rings it in spec. If the cylinder is in spec, wouldn't it be ok to run then? I really appreciate all your opinions. Thank you

I'm getting all my parts before I start to reassemble the bike. The motor is almost done. All that's left is the top end. It's just a bare frame right now. Was green but is now silver. Parts add up fast! Needs new forks also. When I took them off I noticed they were bent. Plus springs cuz I'm 240lbs. Everything is getting something. Master cylinders getting rebuild kits. Carb kit, petcock. But.. adds up fast! I don't want to send the cylinder off. I will if I have to but.. I'm gonna see what the ring gap is with new rings first.

I've certainly seen worse pistons and cylinder bores. IIWIYS, I would scotchbrite scrub the bore, put a new set of rings on the existing piston, assemble the top end and do a compression test. If compression is within the specified limits of 95 - 151 PSI, go ahead and run it.

New rings are cheap, and if the gaps are between .006 - .013", the cylinder bore wear is acceptable. The ring gap should be checked at several places in the bore.

The proof is in the pudding. If the bike's performance was okay before you tore it down, or if it's okay after you just put the new rings in it, then go ahead and ride it. You can always do a re-plate and new piston later if and when it really needs it.

I agree with pumpguy. Except that I would go ahead and replace the piston since you already have it out and it does look pretty beat. Scrub it clean with scotchbrite and WD-40, pop in a piston and rings, test it, and if it's good run it. It's a 200, so you'll be okay with the less expensive pro-x piston rather than having to go with a forged unit. Just make sure you replace that C with another C. The pro-x pistons come in incremental oversize to accommodate slight differences in factory bore.

http://www.wiseco.com/ProductSearch.aspx

They appear to be out of stock of the 'C' piston, but have 'B' & 'D'. You could probably find the 'C' (01.4285.C) on ebay, and cheaper than list price.

http://www.ebay.com/itm/ProX-Piston-Kit ... 8L&vxp=mtr

Oh, deff a new piston. I have no idea how old that one is. Was gonna go with the weisco kit just cuz it's already in the budget. But ya maybe a prox that's one size over will work too. Not sure yet. Where should I start when I'm ready to assemble the bike. Motor in frame and then the swing arm or....? Shock, radiators? My first complete assembly. It sure is fun though! Thank you guys so much for you thoughts! I'm hoping to pass on some knowledge when I'm completely done. Oh just thought of a question. I'm not going to run the odometer, so that cable will not be there but I should be able to use that odometer wheel spacer without the cable connected right? I know there's some after market spacers out there but I'll just use this if I can.

Thank you for the link on the piston!

Once I get new rings and take the measurements I'll know what has to be done. If I need to send it out I will. I'm running this kdx no matter what! I've come to far now!!

When can I do a compression test. I was thinking I had to have the motor in the bike with the carb and plug in there. Kick lever on. Is there a way to bench compression test?

98rebuild wrote:When can I do a compression test. I was thinking I had to have the motor in the bike with the carb and plug in there. Kick lever on. Is there a way to bench compression test?

It would be pretty hard to do a compression test on the bench.