Just wanted to chime in and give another race report on my JX21. Motor has a little over 1/2 gallon and not borken in yet (still has metal pinch). Raced last Saturday and coming in after two 5min heats left about half tank of fuel left. Didn't choose right tires so got stuck in B-main (10min). Figures I have to be either 1st or 2nd to get bumped up so I went all out and told my pit guy I'm not gona come in for fuel in that 10min. Got 1st and made it through the whole 10mins and came in with about 2mm of fuel left in the tank. Overall got 5th place behind 3 factory driver and 1 local driver. Even with those results I'm very happy with this JX21. This is my new fav engine along side the Extech .21.