I would like to make a comment regarding break in of these engines. Most people now days seem to prefer the heat cycle method and it has proven to a very easy and reliable way to break in any engine. As far as the go engines go I reccomend using this version of break in with some slight alterations. First its very important before you turn over any engine to drop some oil into the combustion chamber so that the engine is well lubricated from the first bump, I also think its very important to heat the engine up to 200f before trying to bump it. This puts minimal load on all the moving parts and makes it easy to turn over. These engines are very tight so its important to not over rev the engine too soon. I think it would be good practice to add an extra tank to the first step of the proccess and a extra tank to the last step before trying to force the engine to rev hard. Always be sure to set the engine at BDC immediately after the engine is shut off and try to never let the engine run out of fuel on the track. you will not likely have full performance out of a Go engine until after the first 1 to 1.5 gallons so taking these extra steps during break in can really help ease the engine into a good long life.