Help Plse -- no squirt after 02 YZ carb rebld


Thank you to each of you for such a great place to hang out. I have been lurking for almost a week and a half. It really has become an obsession. I am obsessed to get back to TT and read more of the good stuff that I don't know.

I just got an 02 Yz426 and it didn't run very well at idle and down low. I assumed, due to the bike having been stored for a while here in very hot AZ, it needed a carb cleaning. Well I took the carb completely apart and have now put it back together and hooked up the fuel, checked to see if the bowl had fuel and spun the carb cable wheel ...the wheel where the ends of the throttle cable attaches....and there was no squirt at all.

It did squirt at least a couple of times before I removed it the first time. I am so new to thumpers and this type of carb, I don't even know what I don't know!!!

Any suggestions?? I read somewhere that you have to crack the throttle pretty quickly for the squirt to happen...maybe I am not cracking the slide fast enough with my turning of the carb cable wheel???

Any help would be much appreciated....

Steve Evers

Chandler, AZ

Oh boy, there's a bunch of things to check. In no particular order:

1. Is the leak jet installed?

2. Check the AP diaphram is properly installed / sealed and not ripped or leaking.

3. Check the AP rod and linkages are installed and actuating.

4. Check the nozzle is not clogged.

5. Check the AP timing.

6. Give a good twist of the throttle (probably 1st thing to check)

7. Check the float level.

8. I may have overlooked something.

Nope, the twist doesn't have to be very fast. The AP is not very complicated once you make sure fuel gets there, although the linkage is a bit hidden in the newer FCR.

How about first removing the AP cover(/bottom) and diaphragm and making sure the rod actually moves into the chamber when you twist the wheel?


If you spray or get most carb cleaners on the rubber diaphragm of the accelerator pump, it no longer works.

Often if you spray cleaner on the outside of the carb it runs down the push rod and into the pump chamber, causing the same problem.

Let me know if you want to know how to fix this.



Thank you to all... I will try and go through each of your lists.

Dave, yes, please do tell me how to fix the diaphram...I don't know if my is bad, but I would like to know how to fix it is bad.

Thanks again


Steve - If you did not get any carb cleaner on it, then follow bg10459's advice.

If you did spray things down, you have to dry the carb out.

Remove the float bowl and accelerator bowl. Remove the diaphram and bowl seal. Lay it out on a dust/lint free cloth, (don't bag it) and let it sit overnight in a dry, safe area. Then reassemble in about 24 hours or so. It may help to use some cleaning alcohol and/or soap and water on the rubber items, but I think I would just let it sit.

You may find that when carb cleaner gets on the float bowl gasket, it doesn't fit right, but it too will return to its normal size when left to air out.

Of course, I'll assume that this process will also reveal if there was any gas in the carb to begin with.

Hope this helps.


Hey, I took the carb off and the bowl was still full...I ran down my leg and all over my hands ;-)

It took apart the diaphram holder and checked it all out in there. My thoughts were to do the HB/Doc mod and solder up the leak valve. However I looked at the carb diagrams both on the web and in the Yamaha service manual and put it back together like the photos showed. I think what I did next was just a stroke of good fortune.

Well after it was all back together and full of fuel...still not squirt when I spun the carb slide wheel. I then thought, maybe I need to pump the actual diaphram plunger....HA...that was it...full 10' squirts...yah hoooo. Now I can adjust the slide/squirt timing and then set the squirt duration due to the freshly installed BK mod.

If you think I am jazzed...your right....I can't wait to get it all back together and be a YZ rider again instead of just an old YZ mechanic. ;-)))

I love to work on this bike....but now I just want to feel the.......speed!!!!

Thanks for all your help and support....This TT place is great!!


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