Have had dirt bikes and water craft do this,especially scary on the water craft just testing out of water(can only run about 20 seconds at a time out of water!) If they happen to get too hot they will rev to the moon and you have to choke em down or block the carb with your hands until they die. Doesn't matter what you have on premix ratio,if the carb runs low on fuel while it's running,then the cylinder has less fuel and will run lean and rev! Do as 2strokezilla said by spraying carb cleaner around the carb, boots,etc. If it's sucking air you can tell by the engine speed,PLUS you can smell the carb cleaner through the exhaust as it burns and will burn your eyes from the fumes! OPT

 

Yup the guys are right. When its running out of gas, instead of backfiring like a 4-stroke, they tend to rev really high. Had an old blaster that did it every time. Switch to reserve and problem SHOULD go away.

 

Thats how I know my grandson's blaster is about to run out of fuel. The idle get real high. Just the nature of a 2 stroke.

 

You should be able to replicate the problem by simply turning off the petcock. It should rev high then shutdown.