Another Hawk 250 jet thread. HELP!

Johnetattoo · 03-27-2022, 06:07 PM

I'm at 300ft elevation running a 115 main and honestly haven't noted the VM26 clones pilot size. I'm using the stock exhaust minus the CAT and running a pod foam filter. Only problem is a slightly rich at idle, which a smaller jet may fix. I've ordered what I believe to be the correct pilot assortment to remedy that. What puzzles me is the needles affect on idle. I moved the main jets needle clip down 2 notches to see what would happen at WOT and the bike would barely idle with the idle screw in almost all the way. The plunger was installed correctly also. I was under the impression that the needle height didn't drastically change anything about the pilot circuit. I have moved the clip around and recreated this issue everytime i put the clip any lower than half way. Anyone out there who can school me on why this happens?

tknj99 · 03-27-2022, 06:15 PM

I had a similar issue with the vm26. I started with needle I step below center mark and I found that I had the most annoying hesitation between idle and 1/8th throttle. I moved the needle to center and voila the issue was resolved.. so the needle had an impact at slightest of throttle position off idle. I recommend you keep at middle.

Megadan · 03-27-2022, 07:18 PM

First of all. You need a better understanding of what jet affects what throttle position. The needle is going to have zero effect on WOT. 3/4 to wide open is 95% main jet. A 115 main with a decatted stock exhaust might actually be a tad big. The 115 works well with the aftermarket system, which does flow better than the stock system, even with the cat removed.

The needle mainly affects 1/4 to 3/4 with slight crossover past either end. The pilot jet has the strongest influence up to 1/4, and almost entirely off idle to 1/8th.

A lean idle would be caused by your mixture screw being turned in. That screw adjusts fuel. Turning it out = more fuel. In = less.

Also, a bigger jet numer means richer, not smaller.

If it does use the mikuni pilot and main jets, I would look at a 25 pilot to start, mixture starting at 1 1/2 turns out from seated, and a 112.5 main. Needle in the 3rd notch.

Start by getting your idle mixture dialed in with rhe engine at operating temp. Then, if you notice a slight hesitation at up to 1/8th steady throttle the pilot may still be lean, go to a 27.5 pilot. Then readjust the idle mixture. Once you have all that sorted then you can move on to the main.

Johnetattoo · 03-27-2022, 08:00 PM

Its running rich at idle even with the mixture screw all the way in....gas smell and slight black/Grey smoke. . I'm going to put the clip back in the middle, actually see what pilot came in it and install a leaner pilot I guess. It runs out great with the 115 and the clip in the middle....just that annoying idle that doesn't change with the mixture screw at all. Appreciate the feedback guys.

I said LEAN idle in my original post. Sorry, it's a rich idle I'm dealing with

Megadan · 03-27-2022, 08:59 PM

Quote:

Originally Posted by Johnetattoo

Its running rich at idle even with the mixture screw all the way in....gas smell and slight black/Grey smoke. . I'm going to put the clip back in the middle, actually see what pilot came in it and install a leaner pilot I guess. It runs out great with the 115 and the clip in the middle....just that annoying idle that doesn't change with the mixture screw at all. Appreciate the feedback guys.

I said LEAN idle in my original post. Sorry, it's a rich idle I'm dealing with

Double check the float height while you have it apart, make sure the seat and flow needle (not slide needle) are also functioning. I would suspect the pilot it came with is too big though. Seems to be the case. Too small or too big

Johnetattoo · 03-27-2022, 09:47 PM

Will do. Thanks man

tknj99 · 03-28-2022, 10:34 AM

I get the technical around the needle jet and pilot jet, but, can say from experience, that i tried everything with the stock pilot, adjusting a/f all over the place, and the only thing that helped was putting the needle clip back to center, so im thinking id does have an influence off idle up to maybe 1/4, enough to annoy the heck out of me during rides

Megadan · 03-28-2022, 02:01 PM

Quote:

Originally Posted by tknj99

I get the technical around the needle jet and pilot jet, but, can say from experience, that i tried everything with the stock pilot, adjusting a/f all over the place, and the only thing that helped was putting the needle clip back to center, so im thinking id does have an influence off idle up to maybe 1/4, enough to annoy the heck out of me during rides

It has a small influence from 1/8th to 1/4. I mean, technically all jets are constantly contributing to fueling, that is why I stated, strongest influence at a given throttle position. The pilot jet can alter WOT fueling the tiniest bit as well. Which is why I stated 95% of the fueling from 3/4 to WOT is going to be the main jet. Not an actual accurate number mind you, just an example. It still gets the point across that, at the end of the day, if your fueling is off from just off idle to 1/4 throttle, the pilot jet is going to be the most likely culprit, especially if it is off up to 1/8th throttle. I see way too much bad carb tuning "advice" get tossed around, less so here than the facebook groups, where literally everybodies solution is a stop gap to the tune of "Put in a bigger main jet" or "just adjust the needle" when the persons issue has almost nothing to do with those things. So I take the time to write a novel every time I give carb tuning advice because too many people over simplify things and give horrible advice.

There is a reason I said basically everything I said, and stated the order in which to do those things in. I also always make sure the needle starts in the center and do my pilot and main jets first. They are the easiest to dial in thanks to their strong influence on either end of the throttle sweep, and the main jets influence on the needle and needle jet across the rest of the throttle range.

Johnetattoo · 04-11-2022, 04:34 PM

I was having so much trouble getting the jetting and Idle mixture right. I pulled the carb so many times to end up feeling absolutely dumb...so..... If you buy an extended fuel/air mixture screw... Don't use the spring that came with it. My screw was not seating correctly and was staying completely open/rich no matter the position.

I reinstalled the longer screw but this time used the orig. spring that came in the fake Mikuni and run a 20 pilot and 15 main jet for now. The jet needle clip is in the middle position...3rd notch down I believe. The bike runs great and idles perfectly now. I think I will probably just leave it alone. Until I get bored again

03-27-2022, 06:07 PM	#1
Johnetattoo Join Date: Mar 2022 Posts: 38	Another Hawk 250 jet thread. HELP! I'm at 300ft elevation running a 115 main and honestly haven't noted the VM26 clones pilot size. I'm using the stock exhaust minus the CAT and running a pod foam filter. Only problem is a slightly rich at idle, which a smaller jet may fix. I've ordered what I believe to be the correct pilot assortment to remedy that. What puzzles me is the needles affect on idle. I moved the main jets needle clip down 2 notches to see what would happen at WOT and the bike would barely idle with the idle screw in almost all the way. The plunger was installed correctly also. I was under the impression that the needle height didn't drastically change anything about the pilot circuit. I have moved the clip around and recreated this issue everytime i put the clip any lower than half way. Anyone out there who can school me on why this happens? Last edited by Johnetattoo; 03-27-2022 at 08:04 PM.
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03-27-2022, 06:15 PM	#2
tknj99 Join Date: Oct 2020 Location: Central VA Posts: 1,258	I had a similar issue with the vm26. I started with needle I step below center mark and I found that I had the most annoying hesitation between idle and 1/8th throttle. I moved the needle to center and voila the issue was resolved.. so the needle had an impact at slightest of throttle position off idle. I recommend you keep at middle. __________________ 2024 Zuma Storm 150 DLX 2019 Beta 430 RRS 2018 VStrom 1000 XT Former China Bikes: Tao DBX1, Brozz 250, CSC RX4, Titan DLX, Templar X
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03-27-2022, 07:18 PM	#3
Megadan Join Date: Apr 2017 Location: Omaha, NE Posts: 8,030	First of all. You need a better understanding of what jet affects what throttle position. The needle is going to have zero effect on WOT. 3/4 to wide open is 95% main jet. A 115 main with a decatted stock exhaust might actually be a tad big. The 115 works well with the aftermarket system, which does flow better than the stock system, even with the cat removed. The needle mainly affects 1/4 to 3/4 with slight crossover past either end. The pilot jet has the strongest influence up to 1/4, and almost entirely off idle to 1/8th. A lean idle would be caused by your mixture screw being turned in. That screw adjusts fuel. Turning it out = more fuel. In = less. Also, a bigger jet numer means richer, not smaller. If it does use the mikuni pilot and main jets, I would look at a 25 pilot to start, mixture starting at 1 1/2 turns out from seated, and a 112.5 main. Needle in the 3rd notch. Start by getting your idle mixture dialed in with rhe engine at operating temp. Then, if you notice a slight hesitation at up to 1/8th steady throttle the pilot may still be lean, go to a 27.5 pilot. Then readjust the idle mixture. Once you have all that sorted then you can move on to the main. __________________ Hawk Information and Resource guide: http://www.chinariders.net/showthread.php?t=20331 2018 Hawk 250 - Full Mod list here. http://www.chinariders.net/showpost....62&postcount=1 2024 Royal Enfield Shotgun 650 https://chinariders.net/showthread.php?t=34124
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03-28-2022, 10:34 AM	#7
tknj99 Join Date: Oct 2020 Location: Central VA Posts: 1,258	I get the technical around the needle jet and pilot jet, but, can say from experience, that i tried everything with the stock pilot, adjusting a/f all over the place, and the only thing that helped was putting the needle clip back to center, so im thinking id does have an influence off idle up to maybe 1/4, enough to annoy the heck out of me during rides __________________ 2024 Zuma Storm 150 DLX 2019 Beta 430 RRS 2018 VStrom 1000 XT Former China Bikes: Tao DBX1, Brozz 250, CSC RX4, Titan DLX, Templar X
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03-27-2022, 08:00 PM	#4
Johnetattoo Join Date: Mar 2022 Posts: 38	Its running rich at idle even with the mixture screw all the way in....gas smell and slight black/Grey smoke. . I'm going to put the clip back in the middle, actually see what pilot came in it and install a leaner pilot I guess. It runs out great with the 115 and the clip in the middle....just that annoying idle that doesn't change with the mixture screw at all. Appreciate the feedback guys. I said LEAN idle in my original post. Sorry, it's a rich idle I'm dealing with
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03-27-2022, 09:47 PM	#6
Johnetattoo Join Date: Mar 2022 Posts: 38	Will do. Thanks man
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04-11-2022, 04:34 PM	#9
Johnetattoo Join Date: Mar 2022 Posts: 38	I was having so much trouble getting the jetting and Idle mixture right. I pulled the carb so many times to end up feeling absolutely dumb...so..... If you buy an extended fuel/air mixture screw... Don't use the spring that came with it. My screw was not seating correctly and was staying completely open/rich no matter the position. I reinstalled the longer screw but this time used the orig. spring that came in the fake Mikuni and run a 20 pilot and 15 main jet for now. The jet needle clip is in the middle position...3rd notch down I believe. The bike runs great and idles perfectly now. I think I will probably just leave it alone. Until I get bored again
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