What type of spark plug do you all use the copper core or something else. I had one fowl out luck had it I had a spare. I'm chalking it up to I always mix my fuel with sea foam (1oz per gallon) and it may have been to much for this older atv. Also has anyone ever put a cooling fan in one of these to help with the engine temp, right know I make him ride slow and this is air cooled could that cause a problem? Thanks!!!!

 

I use NGK spark plugs more and more. Had bought new Champion plugs for my Stihl chainsaws and installed them. One was hard starting and the other wouldn't start. Got NGK equivalent plugs and they both started normally.

 

Can I run full synthetic in this ATV? I was thinking of running Royal Purple Max Cycle 10w40

 

Yes, full synthetic is fine, but it should have the jaso spec for the clutch. Diesel motor oils or really anything that does NOT have the little energy conserving shield on it should be ok.

I run one plug range hotter than normal if he is going to be going slow a lot. Helps with the carbon buildup and at least Honda recommends this on some of their smaller air cooled 4 strokes. Also an oil cooler may be as helpful as the fan for alleviating heat. For me it would go to which would be easier to rig up I guess. Personally, unless it is loosing power when he rides, I would be inclined to just go with the hotter plug until he gets faster.

 

IMO, riding slow don't produce alot of heat. They were made to handle it. You could run your car all day slow right?!
I agree on the hotter NGK spark plug.

 

Just make sure the label reads for "wet clutches".
I had a Yamaha 250 Moto4 it was air cooled and had no oil cooler or fan for help and it never over heated once even on the hot slow day rides. If your ATV keeps fouling plugs maybe its a jetting problem.