Am I using the right spark plug?

[frogger812]

Hello

I was driving my 1988 ezgo 2 stroke cart for about a month now. Just the past week It fouls the plug. I can run it for a while then the plug goes bad. I put a new one in, It's fine it will run, But when you stop for a minute then hit the gas to go it will just turn over, but not start. I went through 4 plugs in a week. Now its to the point one ride, then you have to chang the plug. When you take the plug out it has a white looking powder on it

Here is what i'm running for gas, oil, and plug

gas- 93 octane
oil- Ams 2 strock
plug- NGK BP7HS
oil to gas 1.5oz to 1 gallon of gas

what is casing this to happen

thanks frogger