Question Concerning AIS On 99 WR400.

3 replies to this topic
  • standup rider

Posted October 02, 2006 - 08:37 AM


I recently installled a Powernow on the air filtter side of my carb. The OEM part that it replaces had a hose connection that went to the AIS. I capped the hole to that AIS port and also capped the port hole that tee's into the hose line that goes to the port opening that is located between the carb and the engine which also connects to my hot start button. By doing a search in this forum as to disconnecting the AIS there was a number of ways but by plugging the hose that connected to the opening located between the carb and the engine I would not have to change my stock pilot jet so that is what I did.
My question is disconnecting both these lines cause me any potential problems? The bike start and runs well. I noticed that it does not idle as fast as it used to. I also noticed that now when I adjusted my fuel screw which seemed before to idle the fastest at three turns out now idles best when it is turned most all the way in. Closed to 1&1/2 turns out seems to idle about the same.
I have done all the free mods but have stayed with the WR timing. I installed a JD jetting kit and did what was recommended for riding a sea level, (red needle as I remember).
The bike seems to run pretty much the same as before but with better low end responce though it does not seem to rev out as well as it used to.
Any suggestion as to things I need to consider with what I have done?
Want to make sure I did not do something wrong or need to do something more. Thanks for whatever advice you can give.

  • JSanfilippo

Posted October 02, 2006 - 09:09 AM


There is no AIS on a 99 WR 400f, you must be talking about the ACV on the carb

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  • standup rider

Posted October 02, 2006 - 09:29 AM


Sorry about that, thanks for correcting me.

  • neilking

Posted October 02, 2006 - 08:04 PM


The reason you had to turn in the fuel screw is because the hoses you blocked off is causing it to run rich. You need to replace the pilot air jet using the method you chose. The only hose you really need to block to the ACV is the one at the bottom that T's in with the hot start. I took the T out and hooked the hose from the hot start direct to the engine. And plugged the one at the ACV just to keep dirt out of it. That is the hose that actually opperates the device. The ACV is a valve that is normally open connecting the top two hoses, high vaccum from a throttle chop closes the valve to enrichen the mixture to prevent decel popping.


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