i have a 06 trx450er all stock. if i run it every day. no problem if i let it sit for a week it will not start. the only way is to pull it . after you pull start it i have no problem. even the next day it will start right up but if i let it sit for a week i have the same problem and it will not start..

 

try having the valves checked and make sure your fuel is not leaking out of carb and into crank case over that week of setting.

 

if you ave haveing to pull start it thats more of an electrical problem. use a volt meter and see how much juice you battery has aftera week of setting. if its less than 12v you have a weak battery, and it needs to be replaced. really the best thing is to not depend on the pull starter, thats why you bikes comes with electric start lol.

 

have you done a compresion check, my buddies did that and had to put new rings in it.

 

It sounds to me that you have a weak battery.
The battery on the 450er is very small and runs dead quickly while trying to start it.

 

the battery is fine it will turn like hell bu will not fire up

 

i'll have to check that. thanks

 

i'll have to check that. thanks

 

Can I hear your whole start up procedure? On my 07 450ER I pump the gas about 7-10 times, with the choke on hit the start button. DO NOT TOUCH THE THROTTLE WHILE TRYING TO START. You will flood it out.

 

Sounds like a gummed up pilot jet. That makes it lean and that doesn't favor a cold start. Once warmed up, it gets by but you will still be a little lean overall.