yz 426 cutting out!

cr2504life · May 31, 2004

hi my friend just bought a 00 yz 426. When it is idling and he gives it a shot of gas the bike will die but if the motor is revving a bit the bike will not do this. What could be causing this? :bang:

Moto Squid · May 31, 2004

Tuning it on the stand, or while not riding, is useless. While riding when he quickly cracks the throttle does it bog?? If not don't worry about it. If yes try adjusting the fuel screw setting. My thumper has an off-idle bog if I rev it on the stand...but I have the F/S adjusted so it won't bog under load when I'm riding which is all that matters to me.

cr2504life · Jun 1, 2004

yeah it bogs when under load, so did you screw the feul scew out alot?

Ol'89r · Jun 1, 2004

CR.

Sometimes water/dirt in the float bowl or accelerator pump can cause that condition. Make sure the little rubber boot on the accelerator pump rod is in place. If it is dislodged, water and dirt can get in there. Also, make sure all of the rubber hoses on the hot start system are hooked up correctly and the hot start valve closes all of the way.

Refer to the manual for this. If he doesn't have a manual tell him to get one.

Just my $ .02

JasonJ · Jun 1, 2004

sounds like your AC pump is dumping fuel in to fast. You can check it to see if the squirt last less than 2 seconds, its dumping in to fast and you need to modify it. many people just disconnect the AC pump and never look back.

cr2504life · Jun 1, 2004

Does diconnecting the ac pump make the bike perform worse? and How would we unhook it.

Ol'89r · Jun 2, 2004

cr2504life said:
Does diconnecting the ac pump make the bike perform worse? and How would we unhook it.

I don't think I would unhook it. It's there for a reason. :ohmy:

It may be better to adjust it. If you bend the little metal tab at the top of the accelerator pump rod, you can increase or decrease how much fuel is pumped. The trick is to get the proper amount of fuel in at the proper time.

There again, refer to the manual.

IMOE, I've found that the slide needs to open slightly before the fuel squirts into the port.

First thing would be to check the pump diaphram and the cavity that the diaphram sits in to insure everything is clean and working properly.

Just my $ .04

JasonJ · Jun 2, 2004

The pump is disconnected by simpily unhooking or removing the link and securing the hole. Many people that are jetted right and still have the bog just unhook it. The better fix for it is the BK mod or similar where the duration of the squirt is timed and adjusted with a jet or screw. Mine always worked fine, it has like a 2 second squirt and has always worked well for me. There seems to be inconsistancy in in the size of the squirt jet from the casting of the carb, some are ok, some bog, some work fine with the pump disconnected. Jettig has alot to do with it though. You can try to disconnect it, see how it works for you, it cost noting to try. If you feel like it needs the extra hit from the AC pump look into the BK Mod. I think thats what it was called :eek: .

xxdecieverxx · Jun 6, 2004

:clue: mayb its idling too low... ? try that.. or clean the spark plug.. i had that problem once with a old 125

yz 426 cutting out!

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