Everyone brought up the point of richening, which is a good first step. But happywing brought up the use of a temp gauge. I feel a temp gauge should never be discarded. It is possible to tune an engine way too lean even if the engine shoots out tons of smoke and never makes an off-beat sound. This is because different fuels might have a higher oil content. Higher oil does not necessarily keep an engine cool; the additional oil will just burn and spew out more smoke just like a full sized car with a hole in one of its pistons or a seriously worn piston ring such that oil gets into the combustion chamber.

Go ahead and tune the Revo as usual and listen to all the tuning cues. Then, to verify everything is proper, temp the engine and keep it under 300degrees F (must will actually say keep it below 275degrees F). The temp is simply a sanity check and should be used to verify that your tuning skills are correct for the engine, plug, fuel, pipe, outside conditions, etc.

Also, you must learn to take the temp properly. If you already know, then disregard this paragraph. When you take the temp, do your best to aim the temp gauge at the glow plug. If you miss the plug (and you will most of the time), you will get a false cooler reading (another reason why many say temp gauges are BS). When fully warmed up, I always take a battery of 5 readings in one setting and look at the highest #. Then I go for another pass, and take another battery of 5 readings, then go for another pass and take another battery of 5 readings. This is overkill, but I want to be 100% sure of the actual temp. In all, I take 15 readings to get what the engine temp is.