you need to see if it is clutching, eletrical, motor or carb. Check your compression. When it boggs and you shut it off pull the plugs and pull it over to see if both plugs have bright blue spark. Are your clutches really hot? When it boggs stop and check to see if they are REALLY hot..and i mean they may be very hot like 170-200 degrees F so be careful touching them. When it boggs chocke it just a little bit to see if it helps or hurts it. Check your plugs. It may have a lean spot or a rich spot. Choking it just a bit may help it by making it richer. if it is lean check for bad crank seals ect... just try to narrow down at least what it isn't and it will help you lean towards what it is.