Top End Rebuild Problems

[Makeshoes]

Just finished rebuilding my sons top end on his '01 KDX200. Just needed to be done, first rebuild in four years. Bike ran great before rebuild. Got it all back together, started it, it idled 1-2 min then we shut it off. One day later, started it, idled it 1-2 min, then we shut it off. Five minutes later, started it and rode it easily for 1 mile. Shut it off for 10 minutes. Started it and drove 20 yds. My sons thought he heard some noises, not sure if engine noises or something else. Shut it off and wouldn't restart. At this point, bike had little compression felt in the kickstarter. Can easily push the kickstarter now. Feels like all the compression is gone. I am going to start tearing into it this afternoon. You guys have any thoughts? I'm stumped :bang:

 

[Green Hornet]

Check the KIPS & also did the Rings set properly or were installed properly? Looks like you will have to break down again :bang:

 

[Makeshoes]

I thought about the KIPS. But would that make the compression low? When I had the cylinder off, I looked at the KIPS and had my boys look at them also. So we could all see how they worked, sub valves and all. Rings where placed over the pins in the ring grooves. I used the method where you install the piston with rings into the bottom of the cylinder and then install all of that onto the bottom end. I felt like I had the rings installed correctly. Really puzzling about having compression and then not. :bang:

 

[Green Hornet]

Just a stupid question :think: -You used new gaskets right-I know stupid question :think: , but this has got to be a simple problem. If you have the service manual look in the trouble shooting section ans see if there is something listed under compression :( Either way looks like you will have to tearit down again :bang: Hopefully one of the tech suscribers will read this post soon
TTFN

 

[Makeshoes]

Yes, new piston,rings,pin,circlips,top end bearing,Cometic gaskets. Still very puzzled. Going home, eat lunch, start wrenching. Will post any findings. Thanks.

 

[03KDXHOPPER]

Another stupid question...Spark Plug torqued town tightly? Did you align the ring gaps with the machined marks on the piston?

 

[Makeshoes]

Well, I have the answer now. A circlip came out! Chewed up piston and cylinder. I pushed on it around the periphery at least a dozen times to make sure it was fully seated. So now what. 1) Sleeve or 2) Repair or 3) Replace. Can you give me some $ estimates on what you have done from personal experience. My son has talked about moving to a full MX bike so I will have to throw that into the mix to help make the final decision. Thanks for your help.

 

[Green Hornet]

Contact Jeff Fredette & speak w/him. You may be able to have the cylider & ports honed by him & then you will have to install a new piston etc. Also Jeff parts out original KDX parts for very good prices. Go to FRP Offroad.com
Eric Gorr is another you can talk to. Sounds like you caught it early and prevented severe damage. Contact either one of these guys and see. If it can be salvaged your not talking alot of $$$
Good luck

 

[Makeshoes]

Follow up: Seems like $225 was a very popular answer to my asking around what things might cost. Welding, boring, replating, OR oversize boring, replating OR resleeving, all were in that same cost neighborhood. I found a brand new cyclinder at MidWest Action Cycle for $325 and a very nice gentlman from the greater Chicago-land area is going to give me $75 for my used cyclinder as is. So for $250, I well have a brand new cyclinder. I know some of you would have opted for a big bore kit or something, but I just wanted to have what I had before. I sure am going to be bashful about circlips in the future. However, I still believe I didn't do anything wrong. I have installed circlips before and never had one come out.

 

[Green Hornet]

Good for you

 

[canyncarvr]

Maybe I missed it...what kind of piston? OEM, Pro-X or Wiseco?

Wiseco has had a problem in the past with the wrist pin being a bit too long. The circlip is 'in' as far as it will go..but that's not far enough. They come out.

New or not, it's not too hard to ruin a circlip just by installing it. Squeeze it as little as necessary.

Common practice is to install the clip gap at 6 or 12 o'clock. As long as the clip gap doesn't match the piston slot, I don't think it's that big a deal. Take that opinion for what it's worth...pretty close to nada.

 

[Makeshoes]

It was a WiseCo. Thats a great thought. I will measure length of original wrist pin and compare that to the one that was reinstalled with new top end job. Have ordered new piston kit (Wiseco) and will measure that one also. Yes, I do install openings at 6 or 12 o'clock (usually 6 though). Did take 3 tries to get the circlip that came out to seat? in the piston. Thought about using an old piston pin to seat the circlips in the future. Never did hear it "snap" into place though.

 

[Makeshoes]

I can't compare the two wrist pins because the original was a stock piston and the one I put in was a Wiseco. Wiseco is shorter in length because of their design. Anyway, the Wiseco pin length is 1.970. Anyone else have a kit around they could measure and compare lengths? Thanks.