'82 Kdx 250

[DanzKDX]

My KDX hasn't run in 2 years, and here's why.

I was on a track 2 years ago and jumped a "double." When I landed, the bike ran like the throttle was wide open. I took the carb apart and found no apparent problem. I parked it and rode my buddies bike the rest of the time. I then moved and it had been in storage. While it was in storage I talked to a few different shops and they said that the "crank bearing" was leaking allowing air past and causing the problem and suggested a motor rebuild to the tune of $500-$700. Since I bought the bike for $300 this didn't sound good.

I started talking to local guys I saw on the trail when I was on my fourwheeler and one guy said "seals don't just go like that, it is more of a gradual thing." I took his advice and started checking the bike over.

I got a copy of the shop manual (totally out of print) a few months ago and decided to have another go with it. I pulled the carb apart and "dipped" it and it was dirty. I put a new plug in. I checked the reed valve and it is intact. The engine seems to be sealed with no leaks. I looked in the manual and it suggests a mix of 20:1. I was running 50:1 as instructed by a local shop in California 2 years ago. Finally I looked at the air filter because the manual said, "…a damaged or dirty air filter can cause a lean situation." Indeed, it was in pieces. It was old and torn to begin with, when I landed the jump may have finished it off and made it non-existent allowing free flow of air into the motor.

Nonetheless, Unifilter is sending me a new filter and I hope the problems are cured. My theory is that between the filter, the mix, and possibly dirt in the carb caused my "wide open" situation. Having now had experience with small 2 stroke R/C engines, I think I had a "lean" condition and not a throttle/ engine problem.

Any info you could provide would be helpful, I hope to try and fire her up at the end of the week when the filter arrives.



Thanks,

Dan

 

[beefking]

Check for air leaks around the carb. boot- ie check for dry cracks and rips. What did the old plug look like, before you put the new one in?
Also, just double check to make sure that the throttle cable is in good condition, the slide isn't getting cought up on anything.

You said that the airfilter was "torn to pieces"...Personally, I wouldn't ride it knowing that some of that material could have gone down into the cases. May be a good idea to pull the top end at least and look for any obvious damage of the piston/cylinder bore.
Also have a leak-down test (checks the seal of crackcase)and compression test (tests piston and head sealing cababilities) done or do it yourself.

Good luck with the bike. ;)

 

[DanzKDX]

Unfortunately, I was unaware of the state of the filter when all this first happened. I ran it about a total of 3-5min. after it started acting up in an effort to figure it out. The filter was in such bad shape that any thing that may have been sucked into the motor was burnt up during that time. This thing literally fell apart when I took it out of the air box.

Any more info on the leak down test? What is involved with this? Any special tools? I have a friend that has almost a complete shop in his garage and probably could do the compression test there. He knows a lot about 4-stroke street bikes and said we could probably figure it out.

Thanks for the info.

Dan

 

[DanzKDX]

I finally got air filter and installed it. I put air in the tires and was checking the bike over one last time before I started it. I noticed that I was missing a nut off the cyliunder head. I checked the remaining 3 to find that I was able to loosen 2 of them with just my fingers. This would definitely cause an air leak. I got another nut and tightened them all down. Now the fuel petcock is leaking and I have to figure that out before I start it up. The joys of having an old bike, what's next?

Dan

 

[MDA]

DanzKDX,

In light of the fact that the nuts on the head were loose, I would suggest changing the head gasket. Its pretty cheap insurance and would eliminate one more variable in the equation.

Best of luck with the bike,

-Mark-

 

[DanzKDX]

Well, I got it started today and seemed to run O.K. However, after it ran for about 30 seconds, I noticed the fuel shut-off had come apart in the back and fuel was going everywhere except in the motor. Therefore, air was getting into the carb and it started to run funny again. During the time I had it running I noticed the clutch was slipping. This was becuase it was partially engaged because the cable was messed up. I get the bike stopped (kill switch is broken) and take it back to the garage for repairs....again. I try to take the clutch cable bracket off and one of the screws strips, I'm not happy. Since it is a phillips head screw, I take a standard screwdriver and begin tapping into the stripped screw in an effort to get a bit of leverage to break it loose. I know, you're think I'm loosing my mind, right? Anyway, instead of the screw breaking loose, the piece of the transmission it is attached to, breaks off instead, I'm REALLY not happy now. Since I don't have a welder nor do I weld nor can I afford to have someone weld it, I "hillbilly engineer" it. For those of you in the south (I'm originally from West Virgina) you can relate. Out comes the JB Weld and the repair continues. At any rate I hope it will hold, if not I may have to sell it to someone who can fix it or wait till I have the money to fix it. The saga continues.

Later,
Dan

 

[beefking]

Well sounds like you're having one of those days. :scream:

At least you got the problem sorted out...for the most part. About the clutch...you should be able to adjust it at the lever, unless your setup is different. Just need more slack in the line. Check to make sure the cable is routed correctly, no kinks, etc.

The JB weld should hold, it's keeping my pipe together right now...amazing stuff. :)

 

[DanzKDX]

For any of you who have followed this saga, there is finally a happy ending. I did JB Weld the piece on and it holds without a problem. I checked everything over one last time to make sure I didn't have anymore "surprises." I had gotten a set of used fork tubes from Ebay and installed them as well. I went to the street and kicked and she fired right up. I adjusted the idle and hauled some butt around my neighborhood. I don't think they liked it, oh well. At any rate it runs great and still moves out. That thing has more pick up than my 2000 650cc street bike. So needless to say now that it is running great I've decided to sell it. I have a 4 year old that wants to get into riding so I'm selling to get money to eventually by him something. Thanks for all the help you all gave me. Know anyone who wants an '82 KDX that hauls??

Dan