Thanks guys,
On the old howling 110, I'll see if i can get a video next time I'm at the cabin.
It's definitely coming from the gearbox area, and seems to happen once the motor's come up to temp. One at running temp, the howling seems pretty repeatable and the power level needed to start the howling seems to be getting lower and lower.
It sounds a lot like a bearing spinning in a bore, or a shaft spinning inside a bearing race. Some have said this could be a manufacturing tolerance issue in the gear train. I'm a mechanical engineer, so stuff like this tends to bug the crap out of me without knowing a root cause...
For all I know, the older 110 may still need a proper break in procedure too. There are signs of decay, but mainly from elements and being left outside. There are very few signs of actual wear. The tire lugs are till pretty sharp. Funny, the body is 2-tone, but use to be all blue. For quite a while the front end was removed and the remainder faded in the sun... I'm going to sand blast the entire body and try to bring it back to life a bit over the winter.
I'll get a video of the sound, and maybe start a thread about diagnosing the problem. In the mean time, if you guys or anyone else have a photo or two of a 110 semi auto engine with the transmission internals exposed, I'd love to see what I'm getting myself into.
Kelly