Issue with 1/8 conversion....possible motor problem
 

ok I hope I have enough info to make a decent diagnosis.

Last time I raced my hyper 7 conversion (MM - Feigao 9XL) when I would get on the power I would get a very high pitched squeal like metal scraping together. Plenty loud because I could hear it on the track over 10 other nitros. Also it just did not have much power. At first I thought it was the diff and that maybe I had it shimmed to loose and the gear was slipping out of the pin (hope that makes sense). I took the motor out of the buggy and ran it... it starts to get a little high pitched whine to it at about half throttle. Enough that I'm scared to push it much further. Could that be a sign of a bad bearing? Eyeballing it they look ok. I thought also maybe that the pinion was slipping. Not sure it would make that much noise and it seems plenty stuck. It had slipped at one point and made a small grove on the motor shaft but didn't make the kind of noise I'm getting now. Any thoughts or suggestions to try?

It definitely sounds like metal on metal rubbing. The area in question should be getting very hot very quickly after just 30 seconds - 1 minute. I would run it for a minute and temp probe the pinion area, bearings area, and anywhere there is mechanical motion.

Did you say it also lost power? Because I had a Feigao 8XL that had a two magnet rotor and one of the magnets let go (came unglued from the rotor shaft). And it started to make an unusual noise and lost most of it's power (one magnet still attached turned the rotor, but the unglued magnet just spun). You may want to take a look at your magnet(s) and see if they came apart.

I agree with Shark. I got similar things with my 9xl motor when it demagnetized in my 1/8 buggy. Lost power, and had a horrible noise that hurt your ears.

When my 10XL had problems, the only thing I noticed was a drastic loss of power and lots of heat.

Yes there was a loss in power... maybe I should say it "seemed" more like something was slipping because it would barely move and this was accompanied with the nasty squeal. I was too PO'd at the time to check the temp so I don't know about that.