Accelerator Pump "Squirt" Problem

[X400EX]

Hi everyone,

I've got this 450r 41mm FCR installed on my 400ex.

It gives great power, works great on high revs but the problem is that I can't snap it from idle to WOT. It will die.

I've investigated and found that no squirt was coming out of the carb when I've looked at it.

So, I've replace the little rubbed with the spring, thought it was gonna fix my problem... Still no quirt.

I have no leak jet on it, no hole for it or nothing.

I've also tryed to adjust the accelerator pump timmin screw without any results.

Also, cleaned the carb with carb cleaner several times.

I'm really out of idea... What could be the next thing to do?:(

[fmftrx300ex]

umm try a richer main jet?

[cataway]

so with the carb off ,bowl full of gas ,you dont get a squirt of gas when you thumb the throttle ?
did you take it a part and maybe get some thing in up side down ?
do you get a squirt of air or gas to come out of the little orifice in the bore of the carb when air pressure is used ?

[boosted3g]

I know there are a few different diaphrams available for that carb to adjust the amount of "squirt". It should however run with the stock one unless you are running some highly oxygenated fuel that might be the only reason to need more or the fact that the carb is so large. I dont know your state of tune but it sounds like it could be a little lean and the accelerator pump cannot make up the difference. To find out move the move the clip down one notch and see if it gets any better. I run the 04-05 450r on my 400 and i have a slight hesitation but only when it is cold out. I think its because the carb is big for a 400. My hesitation was bad until i used the HRC needle, it cured 95% of it.

[d3ktrix]

Originally posted by X400EX

I have no leak jet on it, no hole for it or nothing.


How is that possible. Are you sure its an FCR?
Leak jets just don't disappear :P
Post a picture of the inside of the float bowel.

[cataway]

its true there are some made with no jet ,
there have been some guys that have plugged the L J to get the full squirt but they also have a way to limit or stop the squirt when they want it to.
you can get an after market bowl that will have a L J

[CSR400EX]

the little brass piece that the gas comes out of for the pump got plugged on my 05. i ended up taking a torch to the little piece and it must have burned out the deposit of whatever it was lol.

[X400EX]

First of all, thank you all for you help.

cataway : What do you mean by when air pressure is used? I just don't get anything out of that little brass piece when snaping the throttle. Where could I put some pressure air to test it?

boosted3g : I think the acceleration pump doesn't make its job well, since I see no skirt with the carb off, bowl full of gas... This is probably why it doesn't make any difference!

CSR400EX : I might try that...


The diaphram and spring I putted into my carb is from CRF 450r 06, a lilttle different (longer shaft) than my stock one but it didn't made any difference.

One thing : I made a test last day, when my motor was hot, more I was pumping the throttle (when it was not running), more it was hard too start after... So does that means that my acceleration pump worked at this time? However, it not seams to work every time.