Top End 1987 KDX 200

[gopack4749]

I bought a 1987 KDX 200 to ride perhaps 3 to 4 times a year with some of my friends. That may not seem like much, but I work 6 days a week and have two kids under 6. So, I am trying to do this on a budget, but have something reliable too. I have no idea on the history of the bike so I figure it is top end time.

Start of disassembly:


More:




Cylinder looks pretty rough, but feels smooth. My fingernail does not catch on anything. Might still need a replate though.


Head:


Piston:


I am pretty certain this thing has not been opened up at all. I am taking the piston, head and cylinder to the local mc repair guy today to have him measure it for me. I will see about plating and getting a piston/rings etc. When I get it back together I will post it all up.

[KDXGarage]

Thanks for the 1987 post.

You may want to check on the throttle housing, as that does not look correct, with it going straight out like that instead of turning.

Also, where the throttle cable goes into the carb, that looks like it has a big gap.

Good luck on the rebuild.

[TrophyHunter]

http://www.bikebandit.com/houseofmotorc ... 1#sch55433

Good catch. Hopefully the link transferred correctly. Looks like the throttle cable routing is missing a few pieces.

gopack - thx for the post. I'll be getting an '86 soon and this and other posts will help evaluate it.

[fuzzy]

Ditch that carb, and install 35mm PWK anyway. May need airbox/cable from 88. 'buff' your cylinder with some scotch brite and see how it looks.

[gopack4749]

Throttle cable does look like it is missing some pieces, but once the air box and carb are in the correct position there is no gap. Just ordered a Wiseco piston and Cometic gaskets. Hopefully I will get it back together without any problems. Bike shop measured old piston and bore and it was good.

[gopack4749]

My parts for the rebuild have come in. Any general assembly tips? I am just nervous about getting the rings and circlips installed correctly. I appreciate any help. Thanks.

[KDXGarage]

You may want to read up on circlip end groove orientation.

[gopack4749]

I got it all back together at about dark last night. I could only do one heat and cool cycle because I was afraid I would piss my neighbors off (was about 9:30pm). I just did between 5 and 10 minutes I guess of idle/no more than 1/4 throttle running. When I first cranked it the idle was high and that startled me I grabbed the idle screw and turned it a little. While it was apart it is very possible that my 2 or 6 year old could have messed with the screw. They like to carry my tools around and beat on things.

[dfeckel]

Good to hear you got it going again. Have fun!

[gopack4749]

Good to hear you got it going again. Have fun!

Went home today during my lunch break to do another break in heat/cool cycle. Bike started up and revved like crazy-I had to hit the kill switch. There must be an air leak somewhere I guess. Cranked it back up and rode it up the road, it died. When I tried to start it back it just would run a little and then die-like a carb problem. Don't really understand because it ran decently before the top end. Gaskets are on right and cylinder and head are torqued correctly. Had to go back to work so I did not mess with it anymore.

What do I need to try next?

[dfeckel]

I would make sure the carb is getting fuel and also make sure that your throttle cable is working properly. I know you had some fitment issues--it could be hanging up and causing to rev. Besides that, as long as the piston went in forwards, there's not much that could go wrong with changing the top end on one of these bikes.

[gopack4749]

Okay. The throttle cable was in a bind and caused the slide not to fully close. Got that problem worked out.

Now brace yourself for how much of an idiot I am...I did not have enough gas in it to keep it running. I had the tank just bolted on finger tight when I did a test start last night. Because of that I put just a splash of fuel in. When I looked at the contents of the tank today-sure enough, no fuel. Anyway added fuel, fixed the throttle cable and fired it up. Ran it for 10 minutes at no more than a third throttle for another break in session. Seems good. Now if I can ever find time to ride it...

[gopack4749]

Here are some pics, sorry I could not document it more but I was working by myself.

New Piston On:


Cylinder On-this was fun, I had to compress the rings with my left hand and slide the cylinder over with my right.


Almost done:


I had asked a question earlier about installing the circlips-I followed this video and it worked great.

[KDXGarage]

Congratulations on getting it going again!