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arwun

Low Idle After Jet Kit Installed?

15 posts in this topic

Mods: Gray Wire removed, Snorkel removed, AIS removed, White Bros silencer.

Started bike & it seems to run okay, but the pipe got red hot. So, I did some poking around on here to see about richening it up a bit. Hence, I also added the JD Jet Kit & Zip-Ty air screw. I used JD's 170 main jet, red needle @ #4 position, and the 48 pilot jet.

I took it out this weekend, and the idle was so low, that it kept stalling. So, I cranked up the idle adjustment until it would stay running. It seemed to run great all day with no problems.

However, I'm not sure that I did the proper thing... just the easiest thing. Should I have instead adjusted my fancy Zip-Ty screw? I didn't because it's kind of a bitch to get to, and pretty difficult to turn. I just set it at 1.5 turns when I installed it, but didn't check to see if it was optimal. What's the proper process for setting the idle screw & Zip-Ty air mixture screw for optimal performance?

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I think the correct procedure is to start at 1.5 turns out, adjust idle with idle speed screw to 1900 rpms and then adjust fuel screw in or out for fastest idle then readjust idle speed screw to correct idle. If you have to in to less than 1/2 turn out or out to more than 4 turns you need a leaner or richer pilot jet. 48 seems to be most common but it depends on temperature and elevation.

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I think the correct procedure is to start at 1.5 turns out, adjust idle with idle speed screw to 1900 rpms and then adjust fuel screw in or out for fastest idle then readjust idle speed screw to correct idle. If you have to in to less than 1/2 turn out or out to more than 4 turns you need a leaner or richer pilot jet. 48 seems to be most common but it depends on temperature and elevation.

How do I know when I'm at 1,900 RPMs? I was just going by what felt/sounded right.

I'm not sure what you mean by "adjust fuel screw in or out for fastest idle then readjust idle speed screw to correct idle".:thumbsup:

I'm in Michigan: elevation ~1,000', temp ~80F

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You don't need to adjust your fuel screw. Just turn your idle up until it doesn't stall.

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You don't need to adjust your fuel screw. Just turn your idle up until it doesn't stall.

Okay; that's what I did, and everything seems A-OK.

In what conditions will I need to adjust the Zip-ty fuel screw... how will I know that it needs to be adjusted?

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Correct me if I'm wrong, but the Fuel Screw adjusts the low end throttle response. Your idle screw is all that would need adjustment in your case. The Fuel Screw should be adjusted to your preference for throttle response and correcting low end bog... Right?

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The fuel screw will adjust the pilot circuit for the most part. It will effect running at a constant 1/8-1/4 throttle. It is the area between idle and the needle being lifted. It can cause popping on decel and sputtering at 1/8 throttle. If you don't have either of these issues then you are good with the fuel screw. If the fuel screw is backed out over 3 turns but your bike runs good then you probably need a bigger pilot jet. The fuel screw should be around 1 1/2 to 2 turns out. If you back it out and it doesn't help I would try a smaller pilot jet. Most people tend to make things too rich.

With all this being said, the adjustment will not work if you main jet and needle height are not correct. These must be figured out first before the low end operations can be set.

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Correct me if I'm wrong, but the Fuel Screw adjusts the low end throttle response. Your idle screw is all that would need adjustment in your case. The Fuel Screw should be adjusted to your preference for throttle response and correcting low end bog... Right?

Throttle response is effected more by the AP squirt. This is the leak jet. This will eliminate the initial bog.

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Okay, so it sounds like I did the right thing by just quickly making an adjustment to the idle screw. Is that common to need to do after rejetting? Or maybe it has always been low & not set properly from the dealer... I rejeted the bike before I ever even rode it.

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It is common.

What's common, that you need to adjust the idle after rejetting, or that you need to adjust the idle after getting it from the dealer?

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What's common, that you need to adjust the idle after rejetting, or that you need to adjust the idle after getting it from the dealer?

Both. Idle adjustment is no big deal. If you change altitude you may need to adjust it as well. Just give a 1/4 turn till you find it runs well.

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Started bike & it seems to run okay, but the pipe got red hot. So, I did some poking around on here to see about richening it up a bit.

On the WR's, the pipe WILL get red hot after idling for a short period of time. The cause is the thin walled header pipe... try sitting at a stoplight after dark and watch the eyes of the guy in the car beside you... not a HUGE problem and certainly nothing to rejet about... You didn`t mention how it ran before you noticed the header...???? If it was running good, don't mess with it... Good Luck, Jamie

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