Well it probably is the timing that is the problem, but try lower gearing first. Even a 14 tooth w/ the 1900 is still as fast as the nitros and a 2050 will be even faster. A note on timing... Using 0 timing with my 1900, I can use ANY size pinion gear up to a 20t in my 8ight and temps will always be less than 140 at the end of the run on 4s lipo.
Check out my custom converted 8ight:
Sub 7lb, lowest CG of any 1/8 buggy