06 400ex wont start up good

[400exbeaster]

hey guys, i was just wondering why my 06 400ex wont start up good? i got a fmf power core4 slip on, k&n air filter, dyno jet kit and a nitro rev box. i just jetted it to 155 main and 3 and a half out of the f/a screw. once its warmed up its idles and starts up good.. any help would be appreciated!

[Foxhound013]

Don't quote me on this, you should prolly wait for someone like steve, ron, or trxracer to pipe in but what is your pilot jet. if its still stock you should get a 42 pilot jet. That should take care of the cold blooded starts. Don't quote me on that though lol. I don't want to steer ya wrong lol. Good luck!

[beags86]

i would put a 42 or even a 45 pilot jet in it and you should be golden.

[400exbeaster]

yeah, its stock pilot jet. soo i'd have to go to a 42 or 45 pilot jet? what do you recomend?

[beags86]

whats your elevation?

[400exbeaster]

im in Ontario, i dont know if that tells you anything

[beags86]

after a goggle search i see your a tick over 2100 ft. go with the 45 pilot. someone else might tell you different, but thats what i would do.

[400exbeaster]

ok, thank you soo much man. you have no idea how much time you saved me!! thanks!!!!

[clemsonteg]

45 will be too large. I have the same setup as you more or less, 06 with a powercore 4 and a uni filter. I run a 158(need to put my 155 in though) and I run a 42 pilot 2.5 turns out. Mine will crank for just a few seconds and then fire up and begin to idle even when its dead cold.

[400exbeaster]

soo 42? the only way to find out really is to try it.. iv'e herd alot of ppl running 42 pilot.. i guess ill try it out.

[beags86]

Originally posted by clemsonteg
45 will be too large. I have the same setup as you more or less, 06 with a powercore 4 and a uni filter. I run a 158(need to put my 155 in though) and I run a 42 pilot 2.5 turns out. Mine will crank for just a few seconds and then fire up and begin to idle even when its dead cold.


personal opinion. i have close to same set up fmf, open box, k&n blah, blah, blah. when i was at 1,000 feet it would fire up right away with no hesitation - dead cold.
i am at 5280 elevation now and run the 42.

i would start with a 42 and see where your at, still hard to start, and go to the 45.

[400exbeaster]

yeah thats what ill do, first ill go 42 and work my way up if needed.

[ridein'red7]

just a possibility but a low battery will make it run like crap with a aftermarket rev box well thats my experience

[dalejiw25]

Now if it were me, I'd put the factory CDI box back in, throw in a 42 pilot, sell the rev box for a nickle minus my 2 cents and ride happily away with a net profit of 3 cents. and never look back. JMO.

[sc400ex_rider]

YA ^^

Also the choke is inop like the rear park brake so dont use it. the carb does have an accelerator pump in it like old cars. so pumping it or flooring it a couple times will prime the engine and help it pop off.