acp problem

1 reply to this topic
  • chepy

Posted January 11, 2002 - 05:00 PM


The last time I did this I typed for two
hours,and then lost the letter,Im a maroon..
Im having that hesitation problem with my new?,
98 400f?....totally stock. I can kill the motor
just by cracking the throttle too fast.....

Im interested in the kh/jd acp mod, but first
I gotta get it to work. The check valve in the
float bowl wont let gas through, Ive blown it out
repeatedly. It allows pressured air through, but
not gas. ( I got it to work once) It would kinda
drip out..but now nothing..does it get sucked -
through? by the diaprahm? its not serviceable is
it ? should I buy a new bowl ? It was very incon-
siestant when it did work. It would hit the the
needle-journal, not the slide. when I put a spacer on the diapram ( to limit stroke) it didnt.
but still, very inconsiestant.
Can you recommend jet sizes, needle,etc..
I ride at 4000 ft and above.

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • F-Pilot

Posted January 11, 2002 - 05:14 PM


Yes there is a check valve in the fill passage to the pump and the diaphram sucks the gas in. I don't think it's servicable but if you have fuel in the pump bowl it's flowing.
The squirt passage can also get clogged. I had to clean mine with spray carb cleaner and compresed air. It took alot of times but finally cleared out.
I would try buying a new diaphram and o-rings first. Also make sure your pump actuation rod moves freely. '98 and '99's had a problem with dirt and corosion there.
If you get it working run a fuel filter, the passages are so tiny = easy to clog.

Related Content

WR Camshaft Swap Info - last post by jamesm113

WR Camshaft Swap Info

  • 0 replies

Yamaha YZ450F 2017 by Chris.GVS

Yamaha YZ450F 2017
  • * * * * *
  • 1 review
  • Last review by Tommyk_55
  • On January 15, 2017

Should I buy this bike? help....... by Numsa Hul

Dirt Bike   General Dirt Bike Forums   What bike should I buy?
  • * * * * *
  • 10 replies

Megabomb Fitment by 288yz450

Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • 1 reply

2016 YZ450 by CaptainKnobby

Dirt Bike   Dirt Bike Technical Forums   Suspension
  • Hot  59 replies

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.