05 450r Carb Questions

[drchoicey]

Good afternoon Gentleman
i was wondering if anyone knew
the purpose of the "air cutoff valve"
and the "carb heater" on the stock
carburetor?
Has any one removed them yet?
What were the effects?

[GPracer2500]

The air cutoff valve cuts off the air supply to the pilot circuit under closed throttle deceleration. The high manifold pressure of closed throttle decel activates the valve. AFIAK, it's purpose is to slightly soften the affects of engine braking by providing an artificially rich mixture under decel conditions. I have not experimented with disabling ACVs so I couldn't comment on the affect of doing so.

Not sure what "carb heater" your refering to. Do you mean "hot start"? The hot start mechanism is basically the opposite of a choke/enrichener. When activated it injects fresh air into the carb to lean the mixture which aids in starting a hot engine.

[drchoicey]

I am referring to the"carburetor heater"
service manual page 16-20
it is some type of electrical device
screwed in next to the mixture screw
Thanx for confirming the cutoff valve function
i believe this might be part of the
"bog problem" in 450r's with stock carbs

[GPracer2500]

Well that's interesting. Now I see what your talking about--didn't know the 04/05 had a carb heater. I know some of the utility quads have carb heaters to aid in the vaporization of fuel in cold temps. The goal is improved cold weather driveability. I assume that the 450r's heater device is there for the same reason???