Ok, I have this setup:
Af16e motor, 78cc Nikasil BBK, v8 28mm exhaust, nh80 carb, UNI filter. 32:1 pre-mix with sa50p cabled oil pump (adds another 1 oz per gal to make 25:1).
At partial throttle, low speeds, I have a bad stumble. I have the sa50 electric choke, #35 pilot jet & #100 main jet. The needle is at the lowest clip. It runs good at half throttle or more. I suspect the choke or pilot jet. Any ideas if the choke is correct or what pilot jet to use? I also may up the main to 105 or 110. I tried a 116 & it was too much. It was really boggy.
Bad low speed stumble.
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TiffanySpree
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- Location: Troy, MI
Bad low speed stumble.
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1986 NQ50d Spree Tiffany green/white - wifeys. Currently modding to get more *!
Early head, exhaust port, intake manifold, intake pod filter, 2.75 rear tire, pulley mod.
1986 NQ50d Spree Tiffany green/white - wifeys. Currently modding to get more *!
Early head, exhaust port, intake manifold, intake pod filter, 2.75 rear tire, pulley mod.
Re: Bad low speed stumble.
at 32:1 premix you may want to remove the pump and plug it. If it idles fine then you may just need to move the clip on the needle to smooth it out 
1986 Spree/ Eve af16 swapped 65cc Prodigy vari 8g 9:1 Ruima gears
21mm OKO 42/100 32:1 45mph kymco zx exhaust
1994 Elite S 17.5mm Arreche, Daytona reeds, SEF ramp, pump plugged
1987 Elite SE50 af16 swapped
1989 Elite E SB50p
2003 Yamaha Zuma
21mm OKO 42/100 32:1 45mph kymco zx exhaust
1994 Elite S 17.5mm Arreche, Daytona reeds, SEF ramp, pump plugged
1987 Elite SE50 af16 swapped
1989 Elite E SB50p
2003 Yamaha Zuma
Re: Bad low speed stumble.
You need a bigger pilot jet. Say a 40 to start.
Bear 45/70
'83 Aero 80 X 3
'84 Aero 80 X 3
'85 Aero 80
'84 Aero 125 X 2
'84 Aero 125
'84 Aero 125 X 2
'85 Aero 50
'85 Spree
'83 Aero 80 X 3
'84 Aero 80 X 3
'85 Aero 80
'84 Aero 125 X 2
'84 Aero 125
'84 Aero 125 X 2
'85 Aero 50
'85 Spree
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TiffanySpree
- Spree
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- Joined: Fri Mar 25, 2011 11:09 am
- Location: Troy, MI
Re: Bad low speed stumble.
Ok, I leaned out the gas a little by draining 1/4 tank and filling with straight gas. Basically, I wanted to remove the oil that the pump would have put in. I don't want to remove the oil pump. I want to avoid any off throttle oil starvation.
The choke seems to work ok but it takes a real long time to warm up and get any decent throttle response. Granted, it is about 45-50 degrees here. That might be part of why it needs a long warm up.
I will plan on the next two sizes on the slow jet. The local mc store didn't have it. What is the Keihen series pilot jet I need to ask for; series 21, 22, etc.? Can I get a bigger factory pilot jet? I'm on my iPhone and I can't check it. I was thinking a 40 & 42 or 45.
I found that once warmed up, it runs really good. My only issue now is the cold running until it warms up. I hope the bigger pilot jet cures it. On my previous af05, I was able to basically rev it a few times and I'm off riding.
The choke seems to work ok but it takes a real long time to warm up and get any decent throttle response. Granted, it is about 45-50 degrees here. That might be part of why it needs a long warm up.
I will plan on the next two sizes on the slow jet. The local mc store didn't have it. What is the Keihen series pilot jet I need to ask for; series 21, 22, etc.? Can I get a bigger factory pilot jet? I'm on my iPhone and I can't check it. I was thinking a 40 & 42 or 45.
I found that once warmed up, it runs really good. My only issue now is the cold running until it warms up. I hope the bigger pilot jet cures it. On my previous af05, I was able to basically rev it a few times and I'm off riding.
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1986 NQ50d Spree Tiffany green/white - wifeys. Currently modding to get more *!
Early head, exhaust port, intake manifold, intake pod filter, 2.75 rear tire, pulley mod.
1986 NQ50d Spree Tiffany green/white - wifeys. Currently modding to get more *!
Early head, exhaust port, intake manifold, intake pod filter, 2.75 rear tire, pulley mod.
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mousewheels
- Veteran OG
- Posts: 3639
- Joined: Tue May 22, 2007 8:10 pm
- Location: North of Seattle, WA
Re: Bad low speed stumble.
Using the base part number of 99103-GC8-XXX, Honda shows part numbers for:Can I get a bigger factory pilot jet? I'm on my iPhone and I can't check it. I was thinking a 40 & 42 or 45.
99103-GC8-0350 #35
99103-GC8-0400 #40
99103-GC8-0420 #42
99103-GC8-0450 #45
99103-GC8-0480 #48
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TiffanySpree
- Spree
- Posts: 162
- Joined: Fri Mar 25, 2011 11:09 am
- Location: Troy, MI
Re: Bad low speed stumble.
Sweet! I'll order now while I wait in line! Thanks!
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1986 NQ50d Spree Tiffany green/white - wifeys. Currently modding to get more *!
Early head, exhaust port, intake manifold, intake pod filter, 2.75 rear tire, pulley mod.
1986 NQ50d Spree Tiffany green/white - wifeys. Currently modding to get more *!
Early head, exhaust port, intake manifold, intake pod filter, 2.75 rear tire, pulley mod.
-
TiffanySpree
- Spree
- Posts: 162
- Joined: Fri Mar 25, 2011 11:09 am
- Location: Troy, MI
Re: Bad low speed stumble.
Whoa! $13.72 for a jet?! I'll buy only one, not two. So, I better think about what size to get. Maybe 42? Better to error on the rich side?
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1986 NQ50d Spree Tiffany green/white - wifeys. Currently modding to get more *!
Early head, exhaust port, intake manifold, intake pod filter, 2.75 rear tire, pulley mod.
1986 NQ50d Spree Tiffany green/white - wifeys. Currently modding to get more *!
Early head, exhaust port, intake manifold, intake pod filter, 2.75 rear tire, pulley mod.
Re: Bad low speed stumble.
Dump that carb with auto choke 
some people dream of speed, i own your dreams!
Re: Bad low speed stumble.
you may want to move the clip on the needle up some could be too rich on the bottom
1986 Spree/ Eve af16 swapped 65cc Prodigy vari 8g 9:1 Ruima gears
21mm OKO 42/100 32:1 45mph kymco zx exhaust
1994 Elite S 17.5mm Arreche, Daytona reeds, SEF ramp, pump plugged
1987 Elite SE50 af16 swapped
1989 Elite E SB50p
2003 Yamaha Zuma
21mm OKO 42/100 32:1 45mph kymco zx exhaust
1994 Elite S 17.5mm Arreche, Daytona reeds, SEF ramp, pump plugged
1987 Elite SE50 af16 swapped
1989 Elite E SB50p
2003 Yamaha Zuma
Re: Bad low speed stumble.
DON'T remove your oil pump. It's an excellent. well-designed device and it's designed to handle 100cc no problem. Premixing oil & gas is for model airplanes, not Honda scooters on the road.Mystic wrote:at 32:1 premix you may want to remove the pump and plug it.
Your problem could be as simple as running gas with ethanol. Like many 2-strokes, my Dio doesn't run worth a d*** with ethanol in the gas. It stalls and stammers. Try a tank full of straight 90+ octane. Costs nothing to check this.