Doing "Stage 1" of that one power increase thread

BladeVortex · 07-07-2019, 11:38 PM

Hello all,

As above, i'm about to do the re-jetting of the carburetor and put in the K&N SU-5589 while i'm at it. Main jets 140, 142.5, 145, 147.5, 150, and 152.5 are on the way in the mail, as well as the air filter. I have already done the 16T sprocket modification.

Currently I think the bike is running close to stoichiometric because the plug is that beautiful tan, and the current air filter is the most disgusting thing i've ever seen inside, absolutely clogged up and looks like a dryer lint trap, so I think this is constricting air flow and making it run stoichiometric, but underpowered.

The bike cruises at 60 mph and anything higher feels like it's over revving. It was scary before the 16T sprocket, I felt like I was in "redline" the whole time.

Anyway, any tips or stuff I should know about before doing this that isn't mentioned in the tread? I'll post my results in this thread as well as any tips for other random kids jumping into something that seems pretty daunting.

BladeVortex · 07-15-2019, 10:53 PM

The jets arrived, so I sawed off that air restrictor and put #140 main jet in. All I can say is oh my god. Top speed went from 65 on a serious downhill to 78 on a gentle downhill. I feel like it should be running rich since I haven't put the K&N in, but I didn't feel the "jerking" he describes for being too rich.

Here's something though, I guess some GZs don't have an adjustable jet needle!
67007531_2050635801899938_8973563394456027136_n.jpg
So I guess what I have to do is buy a couple washers to emulate a 5th position. I'll pick up a bunch in case I ever mess with the exhaust.

BladeVortex · 07-31-2019, 07:51 PM

Before putting the K&N in, I took the stock air filter and cut out the restrictor and let the filter soak in detergent all night. The K&N was on the way anyhow, so if it ruined it, it wouldn't have mattered. The next night there was a layer of silt on the bottom of the container I let it soak in, but after thorough rinsing and drying, I don't feel this improved airflow at all. I modified the exhaust without making it louder, and with the smallest jet that I bought, 140, it was still slightly rich.

After putting the K&N in, I was able to go all the way to the biggest jet I bought, the 152.5, and it is ever so slightly rich I believe which is what I would prefer. With the unfortunate single clip position needle jet, I recommend doing a combination of both the needle jet shim as well as the stuff recommended in the power increase thread, move all the stock pieces on the needle to below the circlip and then what I did was add 2 more washers that are ever so slightly thinner to the suzuki washer. I would say it's about 2.5 "stock suzuki needle washers" between the circlip and the plastic ring. This was the richest I could go with no "jerking".

Part three of the power increase thread I'm finding very concerning. Stock is 1.75 turns out, and he claims that after his modification that he was at 2.25 turns out. I followed his instructions and turned out till the RPM maxed. This occurred distinctly at 5 turns out, not 5.25, not 4.75, a distinct peak at exactly 5, which should be really rich??? Not only does the RPM max at 5 turns out, but it doesn't have any signs of "stalling or doubts" and it drops right to idle RPMs beautifully. Any other settings and I see the symptoms he describes for being lean or rich.

The conclusion? It's as everyone says, a lot more confident in the low and mid range, not much effect on the high end, but it doesn't sound or feel like its going to vibrate in half at 65mph now, and i've hit 78 on huge downhills. So i've got a bike I can bring on the NY thruway now!

So tl;dr im perfectly dialed in after A LOT of work and it's surprisingly rich settings. Strongly recommend this mod to everyone, even non experts.

07-31-2019, 07:51 PM	#3
BladeVortex Junior Member Join Date: Jul 2018 Posts: 20	Before putting the K&N in, I took the stock air filter and cut out the restrictor and let the filter soak in detergent all night. The K&N was on the way anyhow, so if it ruined it, it wouldn't have mattered. The next night there was a layer of silt on the bottom of the container I let it soak in, but after thorough rinsing and drying, I don't feel this improved airflow at all. I modified the exhaust without making it louder, and with the smallest jet that I bought, 140, it was still slightly rich. After putting the K&N in, I was able to go all the way to the biggest jet I bought, the 152.5, and it is ever so slightly rich I believe which is what I would prefer. With the unfortunate single clip position needle jet, I recommend doing a combination of both the needle jet shim as well as the stuff recommended in the power increase thread, move all the stock pieces on the needle to below the circlip and then what I did was add 2 more washers that are ever so slightly thinner to the suzuki washer. I would say it's about 2.5 "stock suzuki needle washers" between the circlip and the plastic ring. This was the richest I could go with no "jerking". Part three of the power increase thread I'm finding very concerning. Stock is 1.75 turns out, and he claims that after his modification that he was at 2.25 turns out. I followed his instructions and turned out till the RPM maxed. This occurred distinctly at 5 turns out, not 5.25, not 4.75, a distinct peak at exactly 5, which should be really rich??? Not only does the RPM max at 5 turns out, but it doesn't have any signs of "stalling or doubts" and it drops right to idle RPMs beautifully. Any other settings and I see the symptoms he describes for being lean or rich. The conclusion? It's as everyone says, a lot more confident in the low and mid range, not much effect on the high end, but it doesn't sound or feel like its going to vibrate in half at 65mph now, and i've hit 78 on huge downhills. So i've got a bike I can bring on the NY thruway now! So tl;dr im perfectly dialed in after A LOT of work and it's surprisingly rich settings. Strongly recommend this mod to everyone, even non experts. Login or Register to Remove Ads
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07-07-2019, 11:38 PM	#1
BladeVortex Junior Member Join Date: Jul 2018 Posts: 20	Doing "Stage 1" of that one power increase thread Hello all, As above, i'm about to do the re-jetting of the carburetor and put in the K&N SU-5589 while i'm at it. Main jets 140, 142.5, 145, 147.5, 150, and 152.5 are on the way in the mail, as well as the air filter. I have already done the 16T sprocket modification. Currently I think the bike is running close to stoichiometric because the plug is that beautiful tan, and the current air filter is the most disgusting thing i've ever seen inside, absolutely clogged up and looks like a dryer lint trap, so I think this is constricting air flow and making it run stoichiometric, but underpowered. The bike cruises at 60 mph and anything higher feels like it's over revving. It was scary before the 16T sprocket, I felt like I was in "redline" the whole time. Anyway, any tips or stuff I should know about before doing this that isn't mentioned in the tread? I'll post my results in this thread as well as any tips for other random kids jumping into something that seems pretty daunting. Login or Register to Remove Ads Last edited by BladeVortex; 07-07-2019 at 11:41 PM. Reason: Mentioning that I am in fact going to contribute to this specific category of the forum
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07-15-2019, 10:53 PM	#2
BladeVortex Junior Member Join Date: Jul 2018 Posts: 20	The jets arrived, so I sawed off that air restrictor and put #140 main jet in. All I can say is oh my god. Top speed went from 65 on a serious downhill to 78 on a gentle downhill. I feel like it should be running rich since I haven't put the K&N in, but I didn't feel the "jerking" he describes for being too rich. Here's something though, I guess some GZs don't have an adjustable jet needle! 67007531_2050635801899938_8973563394456027136_n.jpg So I guess what I have to do is buy a couple washers to emulate a 5th position. I'll pick up a bunch in case I ever mess with the exhaust.
	0