I have a .25 and x1 cobra. The conrod bushing is a very common fault with the motor. I had the same issue at the 5 litre mark but axe came to the party with a warranty. The new motor had the upgraded rod and has done about 25 litres with no problems at all and the x1 has got 45 litres on it (the front bearing has just started leaking). They are a great motor and i think that i will replace the x1 with the x2 as soon as it dies, GO THE AXE.

Chalkie.