Boyesen Accelerator Pump Cover?

a little help here please.

what does that have to do with this topic?

Isn't this thread about the Boyesen cover or did I read the title wrong?

I got the Boyesen Cover and installed it on my 04' 450. There is no more super rip from the bottom. I like the mega thump but its no good for racing in the tight stuff. With the Cover you can snap the throttle and its an instant smooth power transfer. :)

What does the new cover say?

ok, so now that i have a leak jet for my carb and i cant use it, is it possible for me to but a float bowl from a '01 carb and put it on my bike? will it work the same?

You shouldnt need a the leak jet mod at all, especially if you have allready done the BK mod. If you choose to buy the Factory R and D or boyesen acel, cover, make sre and check your pump duration time to see if it changed it at all.

Ohh and buy the way,

No YZF 400, 426 has EVER had a leak jet, thats a brand new thing that yamaha put on there 05's maby there 04 450 has it but im not sure.

there 250F's on the other hand HAVE had them for awhile.

ok, ill mess with the fuel screw and the timing for the shot.

so now that i have a leak jet that i cant use, does anybody want it? ill send it to them for free. just let me know. #50.

Ohh and buy the way,

No YZF 400, 426 has EVER had a leak jet, thats a brand new thing that yamaha put on there 05's maby there 04 450 has it but im not sure.

there 250F's on the other hand HAVE had them for awhile.

the 03-05 definately have the leak jet,oh by the way :)

Im sorry, I didnt know they made a 03-05 YZF 426?? I said I wasnt really sure about the 450's. The guy has a 00 426, and no 400 or 426 has EVER had a leak jet. :)

it's pretty obvious that when someone says 03-05 they're talkin'bout 450's you've gone to the other side(traitor),maybe took a severe blow to the head and need a little extra 'splainin. go adjust your valves :)

Go with the Factory R&D cover, the make one made for the 426, boyesen's are all the same. Talk to Jeff at Factory R&D, and he will tell you the difference. Plus it's billet anodized red! Worked wonders on my 02 YZ426F. It's about the same price as Boyesen's. Better part!

Listen, You were telling Speeddemons, that he needed to change his leak jet, His bike doesnt have a leak jet and eather did any 98-02 , 400-426. We were never talking about any 450's he has a 00 426 not a 450.

So why in the hell do you keep bring up 450's???

Listen, You were telling Speeddemons, that he needed to change his leak jet, His bike doesnt have a leak jet and eather did any 98-02 , 400-426. We were never talking about any 450's he has a 00 426 not a 450.

So why in the hell do you keep bring up 450's???

if your talkin' to me i never told anyone to change their leak jet,i'm referring to how the new ap cover would work with a 40 lj . obviously if the 426 has none;hence "maybe the 00 has none" if the conversation we were having here didn't apply to speeddemon i was trying to help him where to look for it as i was not sure if it had one or not. anything i'm saying is directly related to the 03-05 as that is what i have. NOT a crf go spew crap on the honda forum :)

How does it work with modified carbs such as BK mod ect.?

Repeated rapid throttle opening can deplete the fuel in the AP reservoir quickly causing the engine to stumble. I believe the Boyesen addresses this problem by increasing reservoir capacity, which would provide better response in situations requiring several quick throttle twists, such as hill climbing.
i have the #40 lj and i occasionally experience exactly what you describe (at least it feels that way to me) when i'm in technical sections on and off the throttle every now and again it will just quit. not often but enough.

These posts sum up my interest with regard to this product exactly. I could not get a straight answer on the 250F forum and no "actual" experience in the replies. If you know about the "not invented here" attitude toward new products and new ideas, you'll understand. All I could determine is that if you putt down the trails, the #40 LJ is all you need for an '04.

Nevertheless, I was able to gather from talking to local racers that the QuickShot does indeed keep the motor from bogging in real-world, dynamic throttle demand situations. That's with a #50, #60 or even stock leakjet.

YMMV (disclaimer)

Whats the difference between the Boyesen cover and the P-38 ??? The color??

Reading my most recent Transworld MX they had a very postive review on the product.

They each say that there the best. But I have had verry good luck with Factory R & D, and they have made it for alot longer than Boyesen.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now