I was modifying my accel pump today (BK mod) and realized the pump is not working right.

It only piddles out a little gas and the cam doesn't push the pump all the way. After hours of squirting carb cleaner and compressed air thru the pump fuel passage it still doesn't spray right. If I manually help the actuator it shoots a stream 3 feet long but not on its own. In desperation I removed the spring below the diafram(?) and it seems to work ok but the stream is about 2 sec long like this.

The cam and pushrod are not binding, they move all the way when the pump cover is off.

Is there any way to clean the fuel passage and nozzle better or is it a problem with the tension spring on the cam???

F Pilot

'00 426


You say the rod isn’t binding but other than that your post describes my experiences exactly. The push rod “snaps” into the black actuator arm, unsnap it by pulling it out from the bottom and get after that thing with some emery paper, that is what fixed the problem for me.

I wouldn’t think that the pump would work without the spring under the diaphragm, this is what refills it after each full stroke.

IMO what you have described as far as cleaning the APJ and circuit is more than sufficient to remove any obstructions.

Hope this helps!

BTW, in a rare moment of clarity I realized that the gunk a lot of us find in our accelerator pump from time to time is not getting there via the fuel, it is various stuff that runs down the actuator rod when we wash the carb or bike.


Yea, I read that post, other than the hanging idle it sounds exactly like a disabled pump. Thing runs like crap w/out it don’t it?

You seem to know your way around a carb, you may try jetting your bike with the pump disconnected (since you’ve already figured out how to do this), the high idle may just be an overly lean pilot or idle mixture.

This worked great for me, especially when trying to pick a needle (the ’00 needle was too lean even at 4,000 ft.), but I found that the stock ’00 pump stroke was too long and overpowered my tidy little jetting exercise once I reattached it.

Do a search and you will see how a lot of guys have made their pump stroke adjustable, it is easy (heck, I did it) and made an incredible difference on my ’00 (along with an adjustable Pilot Air Jet, do another search for that).

With the rod not attached to the actuating arm the pump will probably still work, but the timing of it will be off by a country mile, starting and ending way too soon and probably preventing the diaphragm from filling up all the way with fuel. So when you let off the throttle the pump may still be squirting fuel (if there’s any left under the diaphragm) against the back of the slide, this may create a higher idle speed (much like the choke does).

Just take off the entire bowl, grab the arm with one finger and the bottom of the rod with the other and snap it in there. You can try wedging a small slot driver in that little notch in the side of the arm to open the fitting some but mine usually pops right in.

Prob. more info than you wanted but I’ve been away for awhile and needed to vent…

Hope this helps!


(I read your e-mail today)

Hick's ideas sound right on target.

Also make sure the spring that provides pump pressure on the linkages is not gummed up or binding. There are several springs here working opposite directions. Since you are able to work it by hand it seems to be filling OK and has a clear passage. Make sure you don't stretch the diaphram spring out because it is only for re-filling and it should not resist the force from the rod more than necessary.

Let us know what you find out.



Sorry to hear about your woes, wish I could give you advice but I don't know JACK when it comes to the complexity of the 4-stroke.

Hope you get it figure out, I got some work to do before the International also..



Thanks for all the advice, at this point I believe there was a small restriction in the APJ. It caused just enough backpressure that the diaphram ( still can't spell it) wouldn't pump.

I just kept on with the carb cleaner and air and it is working now. One thing that helped is I made a smaller nozzle for the air and was able to direct it at the APJ opening better.

I am riding this weekend, both days, Sat. at Speedworld and Sun. at Canyon!

As far as the acc. pump mod it seem that it will disable any squirt at about 1/2 throttle and above, hence the much larger main??????? Am I on the right track here?


Could you read my post under "need help" posted today? One thing I did not know was that the actuator pump rod needed to be "snapped" in. When I removed the float bowl the rod fell out. When I re-installed I just put it back. I thought it simply pushed the actuator arm. Could this be the cause of my problem.

Thanks in advance!!!

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