400ex dies when doing wheelies

[Brian112233]

hello everyone i just got a 99 400ex on trade. im told it has a fresh motor. here is what i know about the atv and what my problem is. im told it is a 416 kit with polished head and a cam. those are the details i was told. i rebuilt the carb, cleaning the carb itself using my ultrasonic tank. after the cleaning i used a rebuild kit installing all new needles and gaskets. i also used a fmf jet kit, it has the needle on the 3rd clip a stock 38 pilot(and that needs to be bigger) and a 165 main jet, at time of rebuikd(last week) i installed new accelerator pump. the unit has a brand new stock a/c and a brand new ricks motorsports revbox. i can run the machine around for as long as i want on level ground and find no issues but within 40-60 feet of doing a wheelie the engine will die. it will cut out, sometimes if i play with the coke it helps, but usually not. if i play with the throttle i can usually get it to stay running or start back up right away. i have tried running with a/c lid and without, without the a/c installed both with lid on and off, both rick cdi and stock, unit acts up no matter what. i also thought i had a dirthy petcock, removed cleaned using ultrasonic tank reinstalled, no change. thought i had a vacuum lock from a bad fuel cap, tryed loosening and spare cap still no change. any ideas would be a great help.

[Cool Guy07400EX]

I'm confused. When you hit the throttle hard it dies? Or what?

[Brian112233]

no i can run it hard all i want on flat ground, if i do a wheelie it will die, or for another example i have a f250 with a 4 inch lift. i can ride up into the bed on ramps it will die half way up. so basically i cant go up a hill or do a wheelie without it dieing

[Cool Guy07400EX]

Hmmm. I can't think of what would be causing that. Maybe like a clog some where or...I dont know dude. Haha

[Tommy Warren]

are you wheelieing al low rpms like just in first gear going as slow as you can or are you revving it up doing wheelies? do you stay in one gear or switch gears? did you clean you floats? It has to be something to do with fuel delivery

[Brian112233]

i cleaned out every part of the carb, i put it all in the tank, i normally do verybad stuff for 30 min in the tank, i did this carb about 2 hours. (its mine so i did it longer) so yes i did the float chamber. as far as the speed, it doesnt matter, it can be slow first gear, or 2nd gear or it has happened in third when i pull it up then. i get about 3-10 seconds of run time at an angle. as far as the gears it usually doesnt run long enought to swith gears during the wheelie

[Tommy Warren]

what about RPM's? low? high? both? are you blipping the throttle a lot to balance it?

[Brian112233]

both, no matter what i do i can not get it to stay running durring a wheelie, i try fluttering they throttle, wide open, it doesnt matter what i do it dies, front end dropps, if im moving decent in 2nd or 3rd it will start back up if i play with the throttle. otherwise i stop and use the starter and it will usually start back up.

[Cool Guy07400EX]

I was thinkin fuel too. But, I don't know man. Thats a sticky situation.

[gt400ex]

Sounds like a float problem, I would start by double checking that.

[mjc400ex]

Did you try looking at the fuel line?
If there is a fuel filter installed it may be clogged and need to be changed to get better flow while doing a wheelie.
Try replacing the fuel line as well.
Its less than $2 for a foot at any auto parts store.

[hypersnyper6947]

My buddies raptor used to do that too. We never did figure out what it was. I think its definitely carb related. Im not sure if zrpilot comes on the forum any more but i would shoot him a PM he's the master when it comes to carb stuff.

[Brian112233]

yes i tried a new fuel line. i think my check valve in the air cut valve assembly. that would be causing vacuum issue causing the accelerator pump to malfunction. will try tonight and get back to you all.

[Ba9801]

Try going up a steep hill and see if it does the same thing, if it does I would look at the float setting.

[0101]

Originally posted by Ba9801
Try going up a step hill and see if it does the same thing, if it does I would look at the float setting.
Ditto

Sounds like a float problem to me

[Tommy Warren]

he said it dies when he drives it up the ramps into his truck so I'm sure thats what it is.

[Brian112233]

so i took the carb off tonight and found the "float holder" as honda calls it to be loose in the bowl. i must have knock it loose when installing float bowl. so it seems better now. i have to jet it though. thanks for the help.