I have a 1986 Honda TRX250R. I believe it's running too rich because it fouls my plugs. It will turn a new plug moist black, sooty, looks like diesel fuel, it drips out between exhaust and pipe.

1. checked cylinder and boot for air leaks (used radiator pump through the top, plugged exhaust, spray soap/water and watched for bubbles). Also sprayed starter fluid while running, no change
2. checked reeds, okay by 2 mechanics (should I get new anyway?)
3. fuel mix: 32:1, 93 octane pure gas, Honda pure synthetic 2 cycle oil
4. carburetor: air screw 1 3/4 out, 150 main, 48 pilot, clip on 2nd
5. engine displacement: bored 66.50 (Pro X piston and ring kit)
6. compression: WOT cold 150 psi, warm 135 psi, 222' elevation (should compression be higher?)
7. clean air filter, tried with lid on and off
8. exhaust: removed muffler, burnt it out, new packing in silencer
New top end and gaskets, new 35mm Keihin PWK air striker carb, new Pro X crank seals, new Rick's stator, new OEM ignition, Fmf muffler silencer w/new packing, K&N air filter

I have detailed videos I can send. Thank you.

 

First off fuel shouldn't be dripping between the exhaust and pipe. That's probably carb related,float level off,etc. Plug chopping is still one of the easiest ways to check jetting. Just get the engine warm and at a high speed kill the engine and stop as soon as you can. If the plug is still black and sooty,drop a couple main jet sizes and make another test run.Plug needs to be between a tan to medium brown color.

 

 

Sounds a lot like a stuck float or needle valve in the carb. Needle seat could be obstructed or the float is snagged or in need of adjustment. I've fixed this prob in the past by tapping on the carb with the blunt end of a screwdriver. Hope you get er going!

 

"removed muffler, burnt it out, new packing in silencer"

Don't know the 250R but never heard of a two stroke with packing in the exhaust. Any I have come across have baffle type silencers. A four stroke silencer won't work on a tuned two stroke engine. If the float level was well off, the carb would dribble when the engine is stopped. Choke stuck on or a jet worked loose is most likely, but as the engine has been altered, wrong jets or exhaust is a distinct possibility. An ignition fault, causing the engine not to fire every rev is an outside possibility too.

 

Repacked quite a few over here. Exhaust systems may be different across the pond?

 

I must admit I don't do a lot with two strokes, we get a few LT50s and 80s, and the occasional machine with that 90cc Chinese two stroke that Polaris used. Still seems weird to use absorbtion silencers, as all modern two strokes have tuned exhausts, which depend on resonance in the silencer.

 

They still use packing on both atvs and dirt bike silencers, 2 and 4 stroke.Here's a sample from Fmf.Product List : FMF Racing Click on the packing pics and shows for both plus they list the silencers available for the 4 strokes also.