Blocked AP Circuit '99 400f

8 replies to this topic
  • Thommo_400f

Posted July 02, 2012 - 10:27 PM


The small Accelerator pump jet or the passage up to it is totally blocked....
&%$#@! do I do now?
Mechanic doesn't think it is replacable, so is there any way I can clean the damn thing?

Don't really want to spend big $ on a replacement carby .....

ANY advice appreciated


  • MANIAC998

Posted July 03, 2012 - 03:30 AM


Have you tried compressed air? I had one pretty darn blocked on my DRZ, and used compressed air to blow it clean. If that doesn't work, try using a small piece of wire. That is of course, after you've tried any one of hundreds of spray type carb cleaners.

  • mark2506

Posted July 03, 2012 - 03:50 AM


a thin bit off wire and wd 40 will do the trick

  • Thommo_400f

Posted July 03, 2012 - 02:17 PM


Mechanic has soaked it overnight in carby cleaner.
If that hasn't helped I'll go to the hardware store today and get some fine wire and try myself.


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  • Thommo_400f

Posted July 14, 2012 - 02:09 AM


I can JUST get fluid through the little jet. Must still be some debris in there.
During testing I also discovered that the tiny little piston on the end of my needle valve was stuck in which was causing the carb to overflow every time I attached it to the fuel line.
Glad I found out now and not when I put it back in the bike!

  • MANIAC998

Posted July 14, 2012 - 03:34 AM


Keep working at it, and you'll get it! Glad you found the float problem too. These carbs are delicate & finicky, but when you get them dialed in, they work better than the current Fuel Injection out there!!

  • Thommo_400f

Posted July 14, 2012 - 09:54 PM


Finally got a good clear squirt.
Half a can of WD40 injected into the passage under as much pressure as I could manage finally burst clear and the squirt actually hit the roof of my garage!
Re-assembled the carb and got a nice squirt from the acc pump.
Put it back on the bike and it started 2nd kick. Big relief!
Next weekend will be the tester to see if the bog is gone.

Now on to the HANGING IDLE and I'll be a happy camper.

Thanks for the encouragement to keep trying.

  • MANIAC998

Posted July 15, 2012 - 03:45 AM


Congrats!! Just keep dialing in your jetting, one circuit at a time, and you'll have it running well in no time! Check out the stickies at the top of this forum for help with "hanging idle", jetting, etc..

  • Thommo_400f

Posted July 18, 2012 - 01:58 AM


Ap working well
Hanging idle seems to be behaving

Now have major rough running at mid throttle and immediately after a big twist.
If I chug slow and slam it open it launches (ap works) then misses and farts after 20ft and then goes again.
If I slowly open up through range it goes smoothly until 1/3-1/2 and runs rough until wide open.
I've unplugged tps and still same.
So I guess I have to take carb back out, but what am I looking for?



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