thanks mglavin I will read through your reply a few more times to fully understand your explanation....and i have purchased a "R" plug from a local small engine place in Victoria and have tested it tonight in the back yard and i did about 10 laps and not a glich ...looks good so far ....the other question is what would be a good starting point for a prop for this engine the 18.5 I have seemes to bog the engine down ...maybe ile try a 16.5 or somthing ...what about rapping the spark plug wire with aluminum foil just an Idea?