If the super tigers are run in correctly they last forever, at $50Aussie it's worth buying for the spares.

Bearings are cheap from the local bearing shop probably only about $10Aussie.

Some ST engines had problams with the carby leaking at the base, take the carby off and refit with a smear of high temp silicon.

Try an OS#3 plug running on 10% nitro fuel and 20%oil.

hows the compresion when it's hot??

Hows the tank height compared to the needle valve?

it the preassure nipple to the tank blocked?

try flying around at as low RPM as possible and see if you get through a full tank OR set it realy rich, if this works it's probably got bad compression, the low rpm or rich setting keep the engine cooler and there fore the compression higher due to less heat expansion.

but as i said $50 is a good price, on ebay thea 61 would probably be over the $100 ausie mark