built 05 450R main jet problem

[redrider86]

hello ATVRiders,
i have an 05 450R that has a Hmf slip on exhaust, Hot Cams stage2 cam, 13.5:1 Wiseco piston, and a mild port and polish.
the problem is in the main jet. it pops and cuts out above 3/4 throttle. i now have a 225 main jet in it and i am just wondering if i should keep going up in main jets or if i have another problem? the quad runs awesome all the way up the rpm curve till it hits 3/4 to full throttle.

any help will be appreciated.

[mx Eli]

I say go down

[Scro]

That's way to high. Depending on what your airbox setup is, you should be between 160-185.

[mx Eli]

if you have no lid air box ull be 180ish

with lid ull be 165+

depends on exhuast too

[chronicsmoke]

I've got very similar mods with a 185 main and it seems perfect

My elevation is ~200ft.

[redrider86]

but the spark plug is still whitesh and it is not blowing any black smoke. what else could it be??

[redrider86]

oh and its got a KN air filter and i have cleaned the carb twice and recently adjusted the valves.

[Scro]

I would try dropping the jetting first, then we can go from there if it's still acting up. Jetting is more than likely your problem.

[Pacheco_450r]

Originally posted by Scro
I would try dropping the jetting first, then we can go from there if it's still acting up. Jetting is more than likely your problem.

I agree with Scro and the other guys... try going down, the biggest main I've ever ran was a 195.

[400exrider707]

My last 04 bike had 14:1, a stage 3 hotcam, full Curtis Sparks exhaust, no lid and a UNI and we ran a 178 main, and that was dyno tuned. :o

You're way too large on the main.

[fomospede]

what plug you running?

is your float set high enough?

i ,as all the others agree that your main is way to big
no bigger than a 195 main

but no one here thought to think that it is running out of fuel
that would explain the white plug?

just a thought

[400exrider707]

Originally posted by fomospede
what plug you running?

is your float set high enough?

i ,as all the others agree that your main is way to big
no bigger than a 195 main

but no one here thought to think that it is running out of fuel
that would explain the white plug?

just a thought

He did say it's white, but something tells me he's not going out, running WOT, hitting the kill switch with it still WOT, coasting to a stop, pulling the plug and doing a plug chop. It could be lean on every other circuit. I've never seen one need a 225 main and still be out of fuel, UNLESS there is some serious blockage somewhere inside the carb.

If he's doing plug readings the right way then I retract that statement. Most people don't, or simply don't know how. Even less do a physical plug chop (I can't blame anyone for NOT doing it on a $25 plug though).

Sidetrack, but your sig says Cherry Valley? Where's that?

[fomospede]

near chicago