Sounds like you are getting simmilar results as I have. I would suggets a cdi ignition. If you search the net you can find them cheap. The rc exl units work great. You will get a better idle. For the battery pack I have been making all of mine with consumer NiMH AAs. They give 2450 mAH for only $12. I have had no issues with soldering them. My engine is giving the top end speed is what you are getting. I do need to use a a starter because the compression is so low. I run Coleman camp fuel. It stinks less than gasoline, that is my only reason. I find california blend gas really offensive. The Coleman octane is only 40. There is no need to run high octane fuel, it justs cost more than regular gas with no benefit.