Ok, heres the deal. The motor is rebuilt, idles fine, but backfires terribly when under load, and bogs down over half throttle. I tried the timing, and adjusting the high speed jet, but it has no effect at all. The carb is an HR37A. I also tried a HR40A but it does the same thing. I would like to know what the stock carb settings and ignition timing settings. Also what would any of you guys recogmend doing. It has great compression, starts right up, idles great, but wont rev. I rebuilt both HRs.