KDX running bad

[donh]

I have a 1988 KDX200 that won't run right. It just stoped running while i was going down a hill. I had a really hard time starting it back up. Got going again and the bike just started to get bursts of power even when i'm not on the throtle, almost threw me off (wasn't expecting it). Then somehow without touching anything it was in neutral, then stalled.

I don't know if it is related or not but since then, it's been alot easyer to find neutral. I also have alot of oil and gunk around the powervalve and where the exhaust meets the engine (keep cleaning, and it keeps getting gunked up), wondering if it's normal.

If anyone has had the same problem or has any sugestions i would appreciate your help.

Thanks

 

[KelvinKDX]

Don,

A few questions for you first:

How well have you gone through your bike? Is your engine stock or modified? What shape are your reeds in? Have you cleaned you carb recently? What fuel & oil mixture are you using? How is your throttle cable (check routing & movement)?

We need information to be able to give you a good answer.

 

[donh]

I'm pretty new at this so pls. bear with me. The bike is stock. The guy I bought it from seemed to be a straight shooter he said the piston and bearing were done about 6 months ago. I've only had the bike about 3 weeks and put about 35 miles on it. It's run well up until today. Haven't checked the reeds or cleaned the carb Using 40:1 fuel/oil mixture. Throttle cable seems OK. Any advice would be greatly appreciated.

 

[Canadian Dave]

Your problem could be caused by a number of problems. Anything from a bad crank seal to a simple fouled plug. Like KelvinKDX said more info will get you a better answer.

just started to get bursts of power even when I’m not on the throttle

That statement has me thinking there’s an air leak somewhere. Check and ensure the rubber boot between the carb and cylinder are in good condition and not leaking. You can also pull the flywheel off and inspect the crank seal. If there is oil seeping from around it your chances are good its leaking. A note of caution when pulling the flywheel be sure to use a proper puller and don’t smack the flywheel with a hammer etc. 88 and older flywheels are hard to come buy if you damage yours. While you have the flywheel off be sure to inspect the key to insure its in good condition.


For now I'd start with simple things like changing the plug, remove and clean the carb using carb cleaner making sure the jets are unobstructed etc.

No spooge shouldn't be leaking from around your exhaust pipe/cylinder. If you pull the plugs you'll see that there are a couple o-rings around the end up the pipe, where it inserts into the cylinder. Check the o-ring and the copper gasket between the end of the pipe and the cylinder and insure they are all in good condition. Replace them if required. When you reinstall the pipe insure the end of the pipe and its mating surface in the head are clean and run a bead of sili9cone around the o-rings. Enough silicone that it's squeezed our from around the end of the pipe but no so much its forced into the exhaust port. Any silicone will do. Most people will use standard clear silicone because its not unsightly looking. A leak in this area will be costing you power.

David

 

[woodsy]

Dave is right on!! I have found that a simple way to diagnose air leaks is with carb cleaner. Go to your local Auto Zone store and purchase the the Yellow can (here in Muskegon they are 2/1.99). I like this cleaner because it leaves NO residue, drys real fast and works great on electricl components as well as carbs. Start your bike up and with it running spray carb cleaner over the connection between the carb and the jug - dont be afraid to use LOTS of cleaner - if nothing results you will at least have a clean area on your bike :)) ANY change in the motors RPM indicates air leak!! If this proves good shut the bike off, remove the left side cover (fly wheel cover), start the bike up and spray the cleaner behind the fly wheel in the direction of the crankshaft (this is the shaft that the flywheel sets on). Again listen for RPM changes of any kind!!
If it does follow up with seal replacement..
2 pennies
Woodsy

 

[donh]

thanks, i'll check it out and get back to you. I'm pretty sure that itsthe rubber seal from the carb to the cylinder.