1988 Quadzilla (also running poorly)

[174ktm]

I have a 1988 Suzuki LT500R Quadzilla with very low hours on it (~60 to 80 hrs). A few years ago the quad begain running poorly. Started running really rich, not enough power to pull itself around the yard. The tranny oil was a bit low when I checked it so I assumed that I was sucking in tranny oil in thru the crank seal. After sitting for 4-5 years I decided to rebuilt the quad engine this spring.
- rebuilt the bottom end (old bottom end seemed O.K.)
-rebuild the top end (bored out, new piston and rings)
-new V-force reeds (old reeds seemed O.K.)
-changed out the stator (primary coil in the magneto) because the bottom end seals and bearing seemed O.K. (I had bad stators on one YZ 250 that tested O.K.)
-Cleaned out the carb set the floats
-new clutch
-new silencer (stock silencer seemed a little plugged)
-new air filter

Mixed fuel at 40:1
Stock carb (stock main jet 390,)
Started the machine after all this and it ran the same.
The quad will sit there and idle but once you open up the throttle it runs blubbery and really rich. The machine won’t clean out. Spark plug is drenched.
Changed main jet to 340, ran the same
Changed main to 280, ran the same
Checked to ensure timing was correct, it was

Bought a used CDI from ebay. Installed it, and it runs the same

Double checked power valve assembly for correct installation and it is correct.

Options
-I could change out the carb for a Keihin 39PWK (off my KX500) and try this
-The spark plug seem to have good spark, but I could change out the ignition coil
-I have no clue about this option, but I thought I could change out the Pulser coil in the magneto. (I don’t know if these partially fail or completely fail)
-Maybe the stator I bought from Suzuki is NG. and it needs to be replaced?

Any thoughts?

[dan87quest]

mine was the same way. no power seemed rich. i went with the pwk and have had no problems. really woke it up and runs perfect.

[Kane]

Welcome to the site.

Have you checked the needle clip position? The slide, needle, pilot jet, and air screw are your primary suspects. The main jet performs in the upper range and while it WILL affect the running in the 1/4 throttle position it's more likely in those areas you need to look. I doubt it's in the electrics.