It's definitely not the valve lash out of adjustment. I checked that before I did the head to head test between the 100 and 125 and both are adjusted properly.

I guess I could check the cam timing to see if somehow the cam skipped a tooth, but I REALLY don't think that's it since I'm running the same rpm as many others on the Satio threads.

If what "Wind Junkie saying is correct, that the 125 doesn't spool up as fast as the 100, and I've established that they both can turn the same prop at the same rpm, then why wouldn't the 100 be a better motor on any given airplane, since the 100 weighs 3.5 oz less. I of course don't have the answer, but I'm losing faith in the 125 as being better than a 100..