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So i'm going to be installing the Accelerator Pump Diaphragm Kit on an 06 and wanted to know if any other adjustments will be required. I am planning on either reusing the old cover or breaking down and getting a boyesen. Anything special with the new spring or rod that i need to be aware of?

mckenna19 wrote:So i'm going to be installing the Accelerator Pump Diaphragm Kit on an 06 and wanted to know if any other adjustments will be required. I am planning on either reusing the old cover or breaking down and getting a boyesen. Anything special with the new spring or rod that i need to be aware of?

You should upgrade the linkage spring too, as it is THE weak link in the apump system on the early FCR carbs, and, change your leak jet to 50. Both Merge racing and R&D make the updated spring.

Don't bother with the Boyesen cover, but if you must have an adjustable leak jet, look at the R&D brand, as it has been proven to actually work.

I had ordered the Tokyo Mods spring and 50 leak jet. I never really like the o-ring fix anyways. I work high line automotive and roll my eye's when people do that stuff to there cars and i go and do it to my bike. Thanks for the advice on the Boyesen cover seems like i shouldn't need if the spring and diaphragm update fix the bog-hot stall.

I just did that o ring mod to no avail. Is the idea to have a larger cover to hold more gas and prevent air from getting in. My bike rips other than that dam bog and stall.
165 main
45 pilot
45 or 50 leak can't remember
Ncvs 3rd position
Box open
Ti4 complete system

this is what tokyo mods description of the spring is.

[i]The new Tokyomods FCR carburetor accelerator pump spring will increase throttle response and horsepower on all Bikes and quads using an FCR carburetor. This new spring will also alleviate the stubborn bogging problems common with many FCR carbureted Bikes and ATVs. The new Tokyomods spring is designed for the maximum fuel squirt and the optimal squirt duration. Other aftermarket springs are far too stiff; much like wiring your accelerator pump together it shortens the squirt duration and in some cases it can also lead to severe accelerator pump binding problems.

i'm currently chasing the same solution that you are with the bog-stall. i hope this stuff fixes my problem. i lost alot of spots at my last hare scramble due to it.

mckenna19 wrote:this is what tokyo mods description of the spring is.

[i]The new Tokyomods FCR carburetor accelerator pump spring will increase throttle response and horsepower on all Bikes and quads using an FCR carburetor. This new spring will also alleviate the stubborn bogging problems common with many FCR carbureted Bikes and ATVs. The new Tokyomods spring is designed for the maximum fuel squirt and the optimal squirt duration. Other aftermarket springs are far too stiff; much like wiring your accelerator pump together it shortens the squirt duration and in some cases it can also lead to severe accelerator pump binding problems.

i'm currently chasing the same solution that you are with the bog-stall. i hope this stuff fixes my problem. i lost alot of spots at my last hare scramble due to it.

The stock linkage spring is very soft.
In 2008 Keihen went to a stiffer spring.
The Tokyo mods spring is about the same.
The Merge racing spring is stiffer yet, and is more aggressive. It pumps less when you roll on the throttle and more and longer when you whack it.

here's a link to the Merge Racing AP spring mentioned:

http://www.crfsonly.com/catalog/product ... ts_id/4497

ken

Kap wrote:I just did that o ring mod to no avail. Is the idea to have a larger cover to hold more gas and prevent air from getting in. My bike rips other than that dam bog and stall.
165 main
45 pilot
45 or 50 leak can't remember
Ncvs 3rd position
Box open
Ti4 complete system

You need to VERIFY that the pump is working, and timed right. Lift up the subframe and with the engine off, turn the throttle and watch the squirt. It should miss the slide, just barely, but everytime, and squirt a fine stream of gas right into the head, for .8 to 1.2 seconds. The duration is determined by the leak jet (50) and the timing by the linkage screw under the throttle wheel cover (clockwise makes it squirt later).
If the squirt hits the slide, you will get odd issues at idle and just above. If the apump nozzle is clogged, which is common, you will still have major bog.

when you installed the new diaphragm did you make sure to install it in the correct orientation? as Krannie mentions, a clogged AP circuit or nozzle is not unheard of. was your original diaphragm deteriorated? if so, a piece of the rubber could be clogging the plumbing.

ken

Just got an emulsion tube from Phil Wyatt, problem solved.

so was your emulsion tube visible warn or damaged? this just goes to prove there are so many variables at play when a carb isn't working as designed. we would have eventually recommended you look at this! glad to hear you have solved the problem!

I had the tube drilled. Sixteen tiny holes mist fuel instead of a squirt.

I am doing the AP upgrade for an 05' crf450r, and was wondering if I need to use the 50 leak jet? I am using a 55 leak jet right now in my bike, I read the thread on the AP upgrade for crf450r and it did not say anything about the leak yet. Just wondering because I'm getting ready to order everything I need, Thanx! Kenny