Hot running Hiccups

[pdq]

Thats right my 85 kdx 200 hiccups!!
I have 2 running problems when the engine
gets (HOT). It makes this cracking /air poping
noise when excellerating fast and hard under load.
Allso it wont idle, and stalls-out without
some help of the gas. (only when hot)
The engine noise subsides when I
use the choke,but responce is flat.
This bike would be a BLAST! if I
could only fix this popcorn popper..
Any thoughts or help would be appreciated.
Thanks Dave

 

[cweingartz]

Sounds to me like your jetting may be a bit lean. This popping could be caused by the engine lacking fuel. This could also cause the hot running. I would go to the JustKDX website and check out the carb tuning guide if I were you. Good luck with your popcorn popper.

 

[Canadian Dave]

Given the age of your bike I'd also be concerned that it’s running lean because it has an air leak somewhere. Inspect the air boot between the carb and the cylinder and insure its in good condition. Any cracks etc and it may will be sucking air. It’s also possible that its sucking air from around the flywheel side crank seal.

You'll also want to check and insure the carb internals are clean. There could be some junk caught in one of the jets that preventing it from passing enough fuel. Disassemble the carb and hose it down with carb cleaner. Give the jets a shot of compressed air and inspect them to insure they are unobstructed. While you have the carb apart you might also consider checking the float level.

Any chance the spark plug is just fouling?

Good luck and let us know how it turns out.

David

 

[cweingartz]

I just remembered something! Weird huh?
Anyway I once borrowed a friends 84 kdx and it ran way lean. Turns out it was sucking air through the air boot. It was so dry rotted that air was getting through. You can "fix" it by coating it in silicone sealant but if that is the problem I would just buy a new boot. Good luck.