[Shovelheadsparky]

So a little background on this bike. Bought it over the winter. it is a cherry looks like it couldnt have been ridden more than 10-20 hours and original owner said they bought it rode it very little and then it sat in the garage. The frame at the common wear areas (Boot Rub) non existant clean bike. So when i got it it ran but they told me since it had sat they had a friend help clean out carb etc. the first issue was when riding it it would run for about 5 minutes and quit like the amount of time to burn the gas out of the bowl, it also had hard time starting there after. I saw some cracking in the rubber vacuum lines and replaced them as well as this sites reccomendations to jett it with a 42 slow and i recall i put in a 115 main. the needle was non ajustable no notches so i left that as it was. she cranked right up when i hit starter button and ran great... fast forward i would guess 3 hours a few short rides and it wouldnt start. plug was soot blcck tried cleaning plug no dice. replaced plug cranked right up. ran it a short time took plug out pretty black. took it out this past weekend rode it on trails etc. for 2 hours ran fine inspected the plug and was very black.
I asked the guy that ran the track what he thought he says crank case gasket or possibly top end rings etc etc.. Oh when i got it it had top of air box opened and restrictor/ baffle removed. I live in central va Henrico area to be exact so no elevation here..

I am reading a 4 stroke shouldnt be fouling plugs?? any advice would be appricated.. my gut tells me to open the carb change the jetts possibly back to stock and go from there....

[Aussiecrf230]

Well any bike can foul a plug.

Is the fouling black and sooty or oily and black?
If sooty then running too rich so now to work out why.

Does this bike have the baffle in or out of the tail pipe?
Has the airbox been cut to allow more air into the motor?
Is the aircleaner clean and not over oiled? This can make mixture rich.
Can you post up a picture of the plug?
Is it the correct plug installed?

Normally the later standard needles had two grooves , standard and one above to run leaner for higher elevations.

[Shovelheadsparky]

I will try and post a pic... air box is opened and baffle isout of the bike. I did replace air filter and it is one that came pre oiled.

the plug is more soot than oily i will look closer when i get home tonight.