I have an 88' 250R with everything stock except for a uni filter. My plug seems to foul at least ounce everyday and then I have to push it home and switch out the plug and then it runs fine again. I figured it might be running too rich so I took off the air box lid and the plug still got fouled but it took longer. I am running a BR9ES plug and the fuel mixture screw was about 5 turns out with lid on. What should I change or do so it wont keep fouling out? It's getting pretty old switchen out the plug every 2 hours.

PS I run Spectro SX premix, mix 32:1. Thanks Zeebo.

 

Thats why you carry a plug and wrench with you everywhere you go.
Everyone i know who owns a 2-stroke does.

 

What size is main jet?Try going down to next size...do a plug check.
Hows the the compression?.

 

I have done many plug checks and it's always BLACK. The compression is fine. I will go check the main jet now and report back to you thank you for helping DS650DAVE.

 

Contrary to what some will tell you, a 2 stroke does not foul plugs every couple of hours.
There is more of a tendency to foul plugs though with a 2 stroke so you should never ride without a spare plug & wrench. A 2 stroke properly tuned will not foul plugs any more than a 4 stroke. I can ride all summer on the same plug. You would rather run rich than lean with a 2 stroke.
With a 2 stroke it is essential that you keep the air filter clean at all times. I mean clean it before every ride. Don't oil it right before you ride either, do it the night before.
Jetting, needle position, and air screw all need to be set correctly.

Check your compression as DS650 suggested because you normally have to redo the top end on a 2 stroke at least once a year. Ask the guy that you traded your 250X to when the last time he redid the top end on that thing. It's no big deal unless you have a messed up piston or cylinder.
One other thing that can foul plugs on a 2 stroke is a bad crank seal, that may need to be replaced especially on a quad as old as yours.
I bought my 2 stroke used and it took me a year to get it set up right because the guy I bought it from didn't take care of it.

Do yourself a favor and go to a bookstore and pick up a book by Eric Gorr from the motorcycle section. He has a couple out that tell everything concerning 2 stroke engine building & troubleshooting complete with pictures. "Motocross & Off Road Performance Handbook" comes to mind. I attended one of his engine building seminars and he knows his stuff. The books are written for motorcycles but the 2 stroke engine building info applies to any 2 stroke.
Good luck.

 

Looks like you problem. Bad jetting.
Sounds like you're in for an extensive jetting session. top end for the main jet, 1/2 throttle to know if you need to raise/lower the needle...and I still haven't got how to check the pilot.
Always carry a couple plugs with you. Guess what? My dad's snowmobile carries 4 spare plugs!
Keep us updated!

 

Its cool!.....you are looking for bronze color,black is too rich.
It might be best to start with stock settings,For the '88 trx
Slow jet size..#45
Main jet size ..#158
Air screw opening..1 3/4 turns out
needle clip...3rd groove

PS check the carb ,make sure its a PJ07B,the above seetings are for it .

 

Yeah, you need to go smaller on your main and maybe leaner on your needle (move the clip higher) every bike is different, I am runnig a 135 man and I runs great. When I first got the R about 4 moths ago I was fouling a plug every hour, now it never happends and it runs stronger.

 

Well I pulled apart the carb and all those settings are allready there 158 main, 58, and it was at 1 1/2 to 1 3/4 real close to that. I cant do anything til monday night becasue I am out of plugs and the store I can get to is closed.I am glad to see all the replies!![img]i/expressions/face-icon-small-happy.gif[/img] I will keep you guys posted. Thanks Zeebo.

 

"A 2 stroke properly tuned will not foul plugs any more than a 4 stroke"

Craw dad- what is the proper way to turn a 2 stroke , it would probly valuble information for me if i buy an R.