How can I figure my air/fuel mixture on my scoot

[jaranda]

Hello,

I have a 72cc big bore kit on a Lance Charming scoot. I've changed the stock carb with one that has an accelerator pump on it. I have not made any adjustments to this carb, and wanted to know how I can get the air/fuel mix just right. Right now the carb has the jet it came with. I am thinking of installing the main jet that my kit came with, but so far the scooter starts right up and goes up to 37mph on a downhill. When I accelerate, it seems a bit slow to gain acceleration, but once it gets going it will do ok. My scooter does not have a dial that shows the RPM's, so this is the reason I've been reluctant to mess with the carbs mix. How can I achieve this setting to get the most out of this new Carb without having a way to measure RPM'S?

[als01seville]

You are going to have to listen to the engine and listen if it gets faster or slower.
But here is how you get the most out of your Air/Fuel mixture:

ADJUSTING YOUR AIR/FUEL MIXTURE:
YOU WANT THE HIGHEST RPMS OUT OF THE AIR/FUEL MIXTURE SCREW:
This is for you common CV Carbs that have the Air Fuel Mixture Screw Near the INTAKE goint to the Engine. Other Carbs may have the Air/Fuel Mixture On the Air Filter Side with those JUST CHANGE the WORDS "CLOCKWISE to COUNTER CLOCKWISE" and "COUNTER CLOCKWISE to CLOCKWISE" other than that same thing applies.

Before you start it Turn the Air/Fuel Mixture Screw CLOCKWISE UNTIL IT STOPS do not tighten it just until it stops BUT COUNT how many TURNS IT TOOK TO CLOSE it. Then Turn it COUNTER CLOCKWISE the same amount of turns back to where it was.

Then Start your scoot and Get The Engine Nice and Hot about 10 minutes so that the Enricher is no longer Allowing Extra Fuel to come in.

Then do the following to fine tune the Air/Fuel Ratio:

RICHEN THE AIR/FUEL MIXTURE:
1. Turn the Air/Fuel Mixture COUNTER CLOCKWISE 1/4 turn and wait 10-15 seconds to let the engine catch up with the new setting.
a. If the RPMS go up REPEAT 1 UNTIL the RPMS GO DOWN.
b. Then TURN the Air/Fuel Mixture 1/8 CLOCKWISE and that should be your highest Air/Fuel Mixture setting.

"""If on the FIRST 1/4 TURN from the STARTING Position IN #1 ABOVE the RPMS GO DOWN, turn the Air/Fuel Mixture Back the 1/4 turn to the Starting position and wait 10-15 seconds until the engine catchs up and go to #2"""

LEAN THE AIR/FUEL MIXTURE:
2. Turn the Air/Fuel Mixture CLOCKWISE 1/4 turn and wait 10-15 seconds to let the engine catch up with the new setting.
a. If the RPMS go up REPEAT 2 UNTIL the RPMS GO DOWN.
b. Then TURN the Air/Fuel Mixture 1/8 COUNTER CLOCKWISE and that should be your highest Air/Fuel Mixture setting.

IDLE SPEED SCREW:
3. If after adjusting your Air/Fuel Mixture your idle is to fast Turn the IDLE SPEED SCREW COUNTER CLOCKWISE until your Rear Wheel JUST Barely wants to Turn or around 1500-1800 rpms.

4. If 1 or 2 above DOES NOT produce any RPM Change you most likely have a CLOGGED PILOT JET "OR" you did not get the ENGINE HOT ENOUGH and you were working against the ENRICHER which has not yet closed off the extra fuel. If the engine was nice and hot running for about 10 minutes and the Enricher was off then its time to take off the Carb and Clean out the Jets and all the Carb Passages.
Alleyoop

[jaranda]

Aug 10, 2010 2:58:17 GMT -5 als01seville said:

You are going to have to listen to the engine and listen if it gets faster or slower.
But here is how you get the most out of your Air/Fuel mixture:

ADJUSTING YOUR AIR/FUEL MIXTURE:
YOU WANT THE HIGHEST RPMS OUT OF THE AIR/FUEL MIXTURE SCREW:
This is for you common CV Carbs that have the Air Fuel Mixture Screw Near the INTAKE goint to the Engine. Other Carbs may have the Air/Fuel Mixture On the Air Filter Side with those JUST CHANGE the WORDS "CLOCKWISE to COUNTER CLOCKWISE" and "COUNTER CLOCKWISE to CLOCKWISE" other than that same thing applies.

Before you start it Turn the Air/Fuel Mixture Screw CLOCKWISE UNTIL IT STOPS do not tighten it just until it stops BUT COUNT how many TURNS IT TOOK TO CLOSE it. Then Turn it COUNTER CLOCKWISE the same amount of turns back to where it was.

Then Start your scoot and Get The Engine Nice and Hot about 10 minutes so that the Enricher is no longer Allowing Extra Fuel to come in.

Then do the following to fine tune the Air/Fuel Ratio:

RICHEN THE AIR/FUEL MIXTURE:
1. Turn the Air/Fuel Mixture COUNTER CLOCKWISE 1/4 turn and wait 10-15 seconds to let the engine catch up with the new setting.
a. If the RPMS go up REPEAT 1 UNTIL the RPMS GO DOWN.
b. Then TURN the Air/Fuel Mixture 1/8 CLOCKWISE and that should be your highest Air/Fuel Mixture setting.

"""If on the FIRST 1/4 TURN from the STARTING Position IN #1 ABOVE the RPMS GO DOWN, turn the Air/Fuel Mixture Back the 1/4 turn to the Starting position and wait 10-15 seconds until the engine catchs up and go to #2"""

LEAN THE AIR/FUEL MIXTURE:
2. Turn the Air/Fuel Mixture CLOCKWISE 1/4 turn and wait 10-15 seconds to let the engine catch up with the new setting.
a. If the RPMS go up REPEAT 2 UNTIL the RPMS GO DOWN.
b. Then TURN the Air/Fuel Mixture 1/8 COUNTER CLOCKWISE and that should be your highest Air/Fuel Mixture setting.

IDLE SPEED SCREW:
3. If after adjusting your Air/Fuel Mixture your idle is to fast Turn the IDLE SPEED SCREW COUNTER CLOCKWISE until your Rear Wheel JUST Barely wants to Turn or around 1500-1800 rpms.

4. If 1 or 2 above DOES NOT produce any RPM Change you most likely have a CLOGGED PILOT JET "OR" you did not get the ENGINE HOT ENOUGH and you were working against the ENRICHER which has not yet closed off the extra fuel. If the engine was nice and hot running for about 10 minutes and the Enricher was off then its time to take off the Carb and Clean out the Jets and all the Carb Passages.
Alleyoop

Thanks als01seville,

I will do this. I want to make sure that my scooter is giving me its full potential. I am worried that if I am running to rich or lean it might screw up the bike. Thanks again.

[tomcas]

If you're using a 18 to 19 mm carb then you've probably got a 32 to 35 idle jet and a 75 to 78 main jet. If you're using a stock air cleaner with the 72cc kit then leave the idle jet alone and increase the main jet to an 85.

[jaranda]

Aug 10, 2010 20:05:26 GMT -5 tomcas said:

If you're using a 18 to 19 mm carb then you've probably got a 32 to 35 idle jet and a 75 to 78 main jet. If you're using a stock air cleaner with the 72cc kit then leave the idle jet alone and increase the main jet to an 85.

I have an 85 main jet that came with the upgrade kit. I am currently not using it with the carb I've ordered, since I would need a screw removal tool to take the bottom part off. I contacted the manufacture of this carburetor and was told that the carb manufacturer cuts the screws off according to US regulations. After having a few words with that company I ordered from, they are going to send me the unit that was pictured on their website which showed removable screws on the carb. As soon as I get this replacement I will install the 85 main jet. So do you think this will give me a little more speed?