hi im having problems with my spark plugs fouling out. im running 927 castor racing oil and im mixing it 40:1. i was wandering if thats way too much and wat size jet should be recomended, i think i have a size 250 jet in there right now. But if you could help it would be much appreciated....Thanks

 

o the maxima castor 927? thats what i am running in my race car. with the honda 250 engine stroked to 270 on methanol we run between 20 and 25 ounces of oil to 5 galons of methanol. but on my sport i have everything stock with the oil injection.

 

I use 927 and run it at 32-1 and usually do not have much problems unless in just putting around alot then it will foul a plug.

 

The first thing I would do is a compression.
If that is in spec then I would lean you carb main jet out some and see how it feels. Sounds like more of a gas fouling problem than an oil fouling problem to me. I run 40 or 50 to 1 on every two stroke I have and I don't ever remember fouling a plug...............I don't even remember the last time I pulled a plug on one of my two strokes!!!

 

I havn't ever pulled teh plug on my 400 after i taught my 11 year old brother how to not load it up.

 

I noticed your mods.You dont have the stock air-filter system do you?your air-filter is clean?40:1 oil mixture sounds fine.Like Doctorturbo said its probably a jetting problem.your plugs are probably real black when they foul ,if so then go down one jet size at a time until your plug starts looking a brownish tan color.

 

no i have a clamp on k&n air filter and its clean but i pulled the spark plug off and it was not fouled so now its got me thinking that its the carb. Because i like to race and when i thought that the spark plug was fouling was at the beggining of the drag it didnt have no power because it was bogging like the spark plug was fouled. but i got to thinking about it and its getting to much fuel and flooding the carb. eveybody including the atv shop says go down in jet sizes but im running a 230 jet in it right now and it came factory with like 270. do you think that it could be the needle and seat in the carb maybe like the gasket is blown or it couldve swelled because it was made for oil injected but we took that off and are mixing it now. idk just a thought. then do you think that i should buy a new carb or maybe just a rebuild kit