To use or not to use???


4 replies to this topic
  • Wrfrk

Posted August 27, 2009 - 04:52 PM

#1

Ok so I'm trying to get my WR all setup and right now I'm working on jetting. I've had one guy from my area tell me that when he sets up WR's he likes to use the Air&Leak jet's that come with the AIS kit. Well, my bike already came with the AIS system removed but it's a home fabbed kit, well done I might add. However it does not have those jets, so I'm wondering if it's worth it to run them? I've never used them in any other 4t's and I do plan on getting a JD kit.
Honestly I'm not even sure what those jets do and what they would improve. I also understand the only way to get them is to buy the AIS kit from Yamaha?

  • ww44wrf450f

Posted August 27, 2009 - 06:07 PM

#2

Order the jd kit, or get a yz needle and some jets. See you had a 300 ktm? how did you like it? Could you give us an opinion once you get the wr dialed in? also check out your ap squirt and do the o-ring mod (use 2 ) getting the suspension right is a must too! time to grease it and change fork oil, check valves, etc. Be on the safe side on knowing "what's-up". Personally I have been happy with the jets and needle that came with the ais kit, fuel screw, o-ring mod. and a Dr.d slip-on, on the hot and humid days I could tell that I could go a little leaner? It's all-good? But I would say that I am running leaner than other riders settings? as far as my main jet goes?

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  • bg10459

Posted August 28, 2009 - 02:25 PM

#3

The leak jet goes in the float bowl and only affects the accelerator pump. It only comes in to play with a quick blast of throttle, but it's still very important in eliminating the bog. There's plenty of info if you search.

The air jets (pilot air and main air) control the vacuum signal at their respective jets. I believe the main air jet is fixed at #200, but the pilot air jet can be changed. I wouldn't change it, though, unless you're modding the ACV, because it (a larger PAJ) will pull more fuel through the pilot jet, causing an overly rich pilot circuit. Again, there's lots of info on the subject if you search.

Some jets can be ordered from Yamaha and some from Sudco. I don't think you need the AIS kit to get them.

  • Wrfrk

Posted August 28, 2009 - 03:34 PM

#4

The leak jet goes in the float bowl and only affects the accelerator pump. It only comes in to play with a quick blast of throttle, but it's still very important in eliminating the bog. There's plenty of info if you search.

The air jets (pilot air and main air) control the vacuum signal at their respective jets. I believe the main air jet is fixed at #200, but the pilot air jet can be changed. I wouldn't change it, though, unless you're modding the ACV, because it (a larger PAJ) will pull more fuel through the pilot jet, causing an overly rich pilot circuit. Again, there's lots of info on the subject if you search.

Some jets can be ordered from Yamaha and some from Sudco. I don't think you need the AIS kit to get them.


I was not referring to the PJ or MJ, there is a spot in the front of the carb where the airbox boot connects to the carb that houses jet's. There is one in the hole on the left side but not the right, that is where the air jet goes that I ma reffering to.

  • bg10459

Posted August 29, 2009 - 05:26 AM

#5

I was not referring to the PJ or MJ, there is a spot in the front of the carb where the airbox boot connects to the carb that houses jet's. There is one in the hole on the left side but not the right, that is where the air jet goes that I ma reffering to.

Yeah, they're the ones. Like I said, one is the main air jet, which is the one on the right. There's no jet in there because it's fixed at #200, i.e. can't be changed. The other is the pilot air jet which can be changed. The air jets control how much vacuum the pilot or main jets will see, or how much fuel will be pulled through them. A bigger pilot air jet means more vacuum at the pilot jet which means more fuel will be pulled through it, and vice-versa. If you increase your PAJ you will need to make your PJ smaller, but the air cut valve (ACV), or coast enricher, as the DRZ guys call it, will cause problems unless you disable it in the proper manner. I can't remember all the details, but they are there if you search.




 
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