I have a 87 t dub. On my bike the gas cap says "Regular Fuel" so I've always ran regular. I read a thread were some guys said they only run premium fuel in theres. So I went out riding this last weekend and filled up with premium. Wow big mistake. It was to rich for my engine and ran rough all day. I ended up draining my tank and filling with regular, and it returned to running great. Does anyone know why this is?