Hi. Now when the winter has come to sweden it time for me to check the engine. I am new about the thumper, so i dont know what to do whit the engine so it dont break when the mx season starts. I think it would be god to change piston and check the valves. Mayby change cam to a 450 if its necessary...? Did i have to do anything more? Greetings / Gerry Sorry for my bad English... Hope u understand.