Psycocobra

Hello

The piston on my Losi 427 has pitted marks on the top of the piston like some thing has got in there.

All bearings are good. Would it be ok to use until I get a new engine. I suspect it has had the filter off while running as I bought this second hand

RCTecher12

iTrader: (1)

Pitted piston crowns and pitted heads most often means detonation. Too lean.

Gavel

iTrader: (6)

And its usually a symptom of something wrong (running lean) but it shouldnt cause any issues itself.

Troubles Dad

iTrader: (204)

So is it pitted or are they small specs of metal, as did you tear the motor apart to check the bearings and races, and how was the pin where rod and piston meet? As I have had 2 of them motors in the past, one had the rear bearing race start to come apart and could not see till that bearing was out, the other had the rod pin bushing go bad, as for running this motor, it's yours as if everyone tells you it will be great and blows up, I doubt they will offer to fix it, so that choice is ONLY yours to make

Roelof

Can also be caused by a too high compression or nitro content. (both are related)

timjs

If it were me, rather than speculating on what is or isn't happening.. I'd keep running it and save up for another engine.
Many many years doing nitro has taught me to always consider 2nd hand engines to be garbage, because they usually are. And when they aren't, it's the exception not the rule.

22Racer

iTrader: (67)

The rear bearings go out on those pretty often. It is hard to tell a bad bearing most times. The other answer's are good but I suspect the bearing.

Rex

RCTecher12

iTrader: (1)

I hold this to be true for RC car/truck engines most often. I’ve bought used car engines from trusted people that were absolutely fantastic engines - two of which I still have and are stellar runners. In the airplane World, most used engines are often fantastic runners and last for eons. I treat boat Engines in the same context as truck engines - unless the seller is uber trusting, I’d expect it to be junk or on its last leg.