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I dont know much about the accelerator pump but I have heard great things. I just need someone to clarify a little bit. Does it replace the stock carb? And is it worth it to buy?

I'm guessing your talking about the Boysen alcelerator pump cover..

IMO.. spend $0.25 and buy the O-Ring that that does basically the same thing ~ post the sizes a short time ago.. Or if you haven't already buy the JD Jetting kit and it comes with them.. I did that O-Rind mod and can't see any reason to spend $90 on the cover that basically does the same thing the o-ring did=) then you have more money for other go fast goodies

The accelerator pump is part of your carb.

When you twist the throttle, a cam pushes against a diaphragm. The diaphragm forces some gas out through a nozzle into the engine intake.

It causes the RPMs to build more rapidly.

There are mods which can be done to change this effect.

Changes in timing of the squirt, duration of the squirt, and volume of the squirt.

If you have heard of the AP Mod, this is what we are referring to.

i have done all the mods and i did the JD Kit. I have never heard of the AP mod. The Boyesen Quickshot Accelerator Pump is just a cover or what. I am kind of confused now.

~ wrote:It causes the RPMs to build more rapidly.

You mean by covering up the time it takes for the main fuel circuit to add fuel from the venturi effect with a shot of fuel to compensate for the extra air that has not been metered right?

hondacrf450xrider wrote:i have done all the mods and i did the JD Kit. I have never heard of the AP mod. The Boyesen Quickshot Accelerator Pump is just a cover or what. I am kind of confused now.

the earlier versions of the jd jetting kit did not have the ap mods. this was something that wasn't developed early on.

ken

hondacrf450xrider wrote:i have done all the mods and i did the JD Kit. I have never heard of the AP mod. The Boyesen Quickshot Accelerator Pump is just a cover or what. I am kind of confused now.

It is a cover that allows the gas to refill faster than the stock AP cover. Here's the basics of what the cover does. It has two channels built in, one to the nozzle to spray gas, one to the leak jet to leak fuel back into the bowl.

If you are racing and pumping the throttle hard like a two stroke, the stock cover won't refill itself fast enough to give you consistent sprays of gas. The Boyesen cover fixes this issue.

Smash is correct. Without the spray of gas, the engine would stumble before the needle or main would kick in.

alright thanks for clarifying for me

is it worth it?

In my opinion, yes... It makes difference in throtle responce...

FS..

add it you like it. that and a 48 pilot jet
I got all three and it throws some fuel out fast