07400ex doesnt stay running and smokes

[06tacoma]

i just had the top end done on my 07 400ex. i had a 440 big bore kit installed piped jeted and valves also replaced timing chain and tensioner and the damn thing still smokes and has a hard time starting. also back fires alot.

[Exrider434]

needs rejetted?

if im not mistaken, white smoke would mean its burning gas, which would mean its getting too much, because the main jet is too big causing it to run like crap.

Try a couple sizes lower on the main jet and see what happens

[06tacoma]

thanks for that but changed the jets again and still smokes but the smoke is blue not white which tells me its oil and i cant figure that out with the fresh motor.

[mcgrath]

Every time I have a backfiring issue and hard starting it seems to be a timing issue, did you double check the timing?

[400exrider26400]

Originally posted by Exrider434
needs rejetted?

if im not mistaken, white smoke would mean its burning gas, which would mean its getting too much, because the main jet is too big causing it to run like crap.

Try a couple sizes lower on the main jet and see what happens



if it would be burning to much gas de smoke would be black

[400exrider26400]

Originally posted by 06tacoma
thanks for that but changed the jets again and still smokes but the smoke is blue not white which tells me its oil and i cant figure that out with the fresh motor.


maybe to much oil lol ?

[Snipe]

If its white smoke with a blue tint its burning oil, if im not mistaken most rebuild will burn a bit of oil until broken in. Just take it easy on it for awhile until it breaks in if not and you ride it hard you will cause problems and had wasted alot of money.

If its black smoke its burning to much gas, backfiring is usually backfiring out the tail pipe means its running to lean and backfiring in the carb or intake would be a sign of running to rich. Pull the spark plug and look at it. What color is it?