Post by Brandon R on Jul 21, 2007 20:12:59 GMT -5
This is a simple guide for tuning your carb. Works with practically all of the two-stroke carbs.
First we need to know where the tuning screws are. On Viza/Bladez/Evo/China Scooters their carb is called a barrel carb. It looks likes this:
Shot at 2007-07-21
The low speed screw is located on the very top, in the middle of the black barrel swivel. Most of them are gold. It should generally be 1 full turn out. (turn it in till it stops, DO NOT TIGHTEN, then turn it out.) you might have to turn it alittle one way or the other for it to start. Turning it in will produce a higher idle and out will produce a lower idle. Now for the high speed screw. It should be anywhere from 1 1/2 turns out to 2 full turns out. this is the part where you must ride to find the good settings.
Go by these hints to help tune it to your preference.
If your engine stutters at full throttle and cannot reach full RPMs:
The high jet is too far open. Close the jet by turning it clockwise slightly, and then ride-test. If no improvement, repeat until desired results are achieved. Once you have found a workable setting, open the jet approx 1/16 of a turn to ensure sufficient fuel/air mix.
If your engine bogs out when transitioning from low speed:
The high jet is too far closed. Open the jet by turning it counterclockwise until you are at least 1 1/2 turns open, and then gradually close the jet until performance is as desired. Poor engine compression, blocked exhausts, and very heavy engine loading can all also cause bogging.
If your engine idles very fast and kills if you attempt to slow the idle:
You may have an air leak in your intake. An easy way to check for leaks is to spray the intake manifold and area surrounding it with WD-40. If the idle changes after you spray the WD-40, there is an air leak. Common areas for leaks are between the manifold and the cylinder, and between the carb and the intake manifold. Inspect the manifold, carb gasket, and intake gasket for cracks or other signs of damage, and replace if necessary.
If your engine idles but then slowly kills:
Your low jet is too far open. Close the low jet by turning it clockwise until a stable idle is achieved.
Now for the Butter fly carbs. Their mostly found on Go-Peds and some weedwackers. They look like this:
Shot at 2007-07-21
Before adjusting the carb on your Go-Ped, make sure your spindel isn't too tight. That can can horrible engine response. (To test to see if it is your spindel, loosen it. Ride. If it runs better problem solved. If not, continue reading.)
Both of the adjustment screws are beside each other. Their marked L for LOW and H for HIGH. Turn both of them in untill they stop, DO NOT TIGHTEN, then turn the low speed out about 1 - 1 1/2 turns out. (You might have to turn it one way or the other to start it) Turning it in will produce a higher idle and out will make a lower idle. Too far and it will flood it and it will shut off.
Turn the H screw out about 1 1/2 turns out. Ride the scooter and Use these hints to find your preffered settings.
If your engine stutters at full throttle and cannot reach full RPMs:
The high jet is too far open. Close the jet by turning it clockwise slightly, and then ride-test. If no improvement, repeat until desired results are achieved. Once you have found a workable setting, open the jet approx 1/16 of a turn to ensure sufficient fuel/air mix.
If your engine bogs out when transitioning from low speed:
The high jet is too far closed. Open the jet by turning it counterclockwise until you are at least 1 1/2 turns open, and then gradually close the jet until performance is as desired. Poor engine compression, blocked exhausts, and very heavy engine loading can all also cause bogging.
If your engine idles very fast and kills if you attempt to slow the idle:
You may have an air leak in your intake. An easy way to check for leaks is to spray the intake manifold and area surrounding it with WD-40. If the idle changes after you spray the WD-40, there is an air leak. Common areas for leaks are between the manifold and the cylinder, and between the carb and the intake manifold. Inspect the manifold, carb gasket, and intake gasket for cracks or other signs of damage, and replace if necessary.
If your engine idles but then slowly kills:
Your low jet is too far open. Close the low jet by turning it clockwise until a stable idle is achieved.
Now the Idle screw. The idle screw on the barel carb is located on the top to the side. It's generally gold. Turn that in enough for the scooter to run, but not engage the clutch. ( on spindles, turn it in enough to keep the engine running without shutting off with it in the air)
The idle on the butterfly carbs is generally silver. It's located in different areas for different engines. Look for the throttle plate (The piece of metal your throttle cable connects to, unless it's a Chung Yang, then it's on the opposite side the cable is) Adjust as said Above.
First we need to know where the tuning screws are. On Viza/Bladez/Evo/China Scooters their carb is called a barrel carb. It looks likes this:
Shot at 2007-07-21
The low speed screw is located on the very top, in the middle of the black barrel swivel. Most of them are gold. It should generally be 1 full turn out. (turn it in till it stops, DO NOT TIGHTEN, then turn it out.) you might have to turn it alittle one way or the other for it to start. Turning it in will produce a higher idle and out will produce a lower idle. Now for the high speed screw. It should be anywhere from 1 1/2 turns out to 2 full turns out. this is the part where you must ride to find the good settings.
Go by these hints to help tune it to your preference.
If your engine stutters at full throttle and cannot reach full RPMs:
The high jet is too far open. Close the jet by turning it clockwise slightly, and then ride-test. If no improvement, repeat until desired results are achieved. Once you have found a workable setting, open the jet approx 1/16 of a turn to ensure sufficient fuel/air mix.
If your engine bogs out when transitioning from low speed:
The high jet is too far closed. Open the jet by turning it counterclockwise until you are at least 1 1/2 turns open, and then gradually close the jet until performance is as desired. Poor engine compression, blocked exhausts, and very heavy engine loading can all also cause bogging.
If your engine idles very fast and kills if you attempt to slow the idle:
You may have an air leak in your intake. An easy way to check for leaks is to spray the intake manifold and area surrounding it with WD-40. If the idle changes after you spray the WD-40, there is an air leak. Common areas for leaks are between the manifold and the cylinder, and between the carb and the intake manifold. Inspect the manifold, carb gasket, and intake gasket for cracks or other signs of damage, and replace if necessary.
If your engine idles but then slowly kills:
Your low jet is too far open. Close the low jet by turning it clockwise until a stable idle is achieved.
Now for the Butter fly carbs. Their mostly found on Go-Peds and some weedwackers. They look like this:
Shot at 2007-07-21
Before adjusting the carb on your Go-Ped, make sure your spindel isn't too tight. That can can horrible engine response. (To test to see if it is your spindel, loosen it. Ride. If it runs better problem solved. If not, continue reading.)
Both of the adjustment screws are beside each other. Their marked L for LOW and H for HIGH. Turn both of them in untill they stop, DO NOT TIGHTEN, then turn the low speed out about 1 - 1 1/2 turns out. (You might have to turn it one way or the other to start it) Turning it in will produce a higher idle and out will make a lower idle. Too far and it will flood it and it will shut off.
Turn the H screw out about 1 1/2 turns out. Ride the scooter and Use these hints to find your preffered settings.
If your engine stutters at full throttle and cannot reach full RPMs:
The high jet is too far open. Close the jet by turning it clockwise slightly, and then ride-test. If no improvement, repeat until desired results are achieved. Once you have found a workable setting, open the jet approx 1/16 of a turn to ensure sufficient fuel/air mix.
If your engine bogs out when transitioning from low speed:
The high jet is too far closed. Open the jet by turning it counterclockwise until you are at least 1 1/2 turns open, and then gradually close the jet until performance is as desired. Poor engine compression, blocked exhausts, and very heavy engine loading can all also cause bogging.
If your engine idles very fast and kills if you attempt to slow the idle:
You may have an air leak in your intake. An easy way to check for leaks is to spray the intake manifold and area surrounding it with WD-40. If the idle changes after you spray the WD-40, there is an air leak. Common areas for leaks are between the manifold and the cylinder, and between the carb and the intake manifold. Inspect the manifold, carb gasket, and intake gasket for cracks or other signs of damage, and replace if necessary.
If your engine idles but then slowly kills:
Your low jet is too far open. Close the low jet by turning it clockwise until a stable idle is achieved.
Now the Idle screw. The idle screw on the barel carb is located on the top to the side. It's generally gold. Turn that in enough for the scooter to run, but not engage the clutch. ( on spindles, turn it in enough to keep the engine running without shutting off with it in the air)
The idle on the butterfly carbs is generally silver. It's located in different areas for different engines. Look for the throttle plate (The piece of metal your throttle cable connects to, unless it's a Chung Yang, then it's on the opposite side the cable is) Adjust as said Above.
