I AHVE A 1984 ATC250R IT HAS BEEN BORED .30 OVER WITH THE WISECO SUPER LITE PISTON,PORTED AND POLISHED. IT HAS A DG PIPE AND SCILENCER, FMF REEDS,K&N AIR FILTER.IT WILL RUN GREAT FOR ABOUT A HOUR STOP AND GO THEN I WILL GO TO RIDE FOR A WHILE AND THEN IT WILL JUST DIE. AND WHEN I TAKE OUT THE SPARK PLUG IT WILL BE COVERED IN OIL ADN WHEN I CHANGE THE SPARK PLUG AGAIN IT WILL DO THE SAME THING OVER AGAIN I RUN THE OIL AT 32:1 AND THE STOCK RATIO IS 20:1. ANY HELP WILL BE APRECATIED.. IF YOU THINK OF ANYTHING PLEASE EMAIL ME YOUR SUGESTIONS TO WARRIORLAX17@HOTMAIL.COM

 

Barring some sort of mechanical problem, like crank seals being bad, it sounds like you need someone to jet the thing for you. It's too rich, this is what is fouling your plugs. You might try one heat range hotter spark plug as a temporary fix. If you are running an NGK B9ES then try a B8ES, if running a B8ES then try a B7ES, I wouldn't go much hotter than a 7 though, especially if stock is a 9.

 

DEFFINATELLY DO SOME JETTING CHANGES. DG SAYS TO GO UP TWO MAIN JET SIZES WHEN USING THE PIPE AND SILENCER, BUT I FOUND THE STOCK JETTING WAS JUST FINE, BUT YOU SHOULD TAKE PLUG READINGS. MY 84 WAS 80 OVER WITH WISECO PISTON, BOYESEN REEDS, DG PIPE AND SILENCER. JETTING WAS HARD WITH THE STOCK CARB, BECAUSE PILOT JETS I COULD NOT FIND ANYONE WHO HAD THEM. I WENT WITH A 34mm MIKUNI CARB, ALL JETS ARE AVAILABLE. IT JUST MAKES IT INTO THE FLANGE, BUT IT MADE IT. AND WHAT A DIFFERENCE THE CARB MADE AFTER GETTING THE JETTING CORRECT.
YOU WANT TO GET THE PLUG COLOR TO BE A CARDBOARD COLOR.

84 ATC 300R
86 ATC 200X

 

I have a '82 trike 250R. I was having the same prob. Mine is .80 over w/ Wiseco piston, Boysen Reeds & DG silencer. I now run mine 20:1 with the stock jet & it screams.
http://bardosatvpage.freeservers.com/index2.htm
I just recently put on a new front end & a new paint job. Check out my web page to see the sad shape this Trike was in when I bought it for $100