Engine bogs down when revving throttle By neil2no1 (Read 1,649 times)

[neil2no1]

    I'm a new scooter owner whose scooter bogs down when I rev the throttle, I have tools to go into the different engine components, I have already disassembled the the combustion chamber, cleaned it, resealed it and put it back together. I have taken the carburetor apart, it is clean. I'm new to mechanic work and i guess I don't really know too much about troubleshooting it. please help, I can give more details if and when necessary.

[twowheeler]

Is this a new scoot? If not check for air box cracks or cracks in the intake tube. The elbow where the carb attaches sometimes cracks as well.It might be getting too much air and these are finicky. There should be a cap of some sort on the end of the air intake as well. Also, since you have had the carb apart make sure you didnt pinch the rubber diaphram under the lid. Did you inspect it for holes?

[scatterbrained]

Are there any other symptoms such as back firing or popping through the carb ect?

[Bashan]

The guys are spot on. The first thing you suspect with bogging is inadequate vacuum in the carb. With a CV carb there is no direct connection between the throttle and the fuel delivery system. The throttle opens the butterfly and the rush of air over the venture causes a vacuum that raises the diaphragm and the jet needle. If the needle doesn't raise adequately you get mostly air and little gas which equals bogging. The lean mixture can sometimes make it pop also. So...what they said. I'm just here to complicate things. Make sure there's no air leaks both sides of the carb. The intake manifold leak that TW alluded to can be tricky. They can be hidden until you pull the manifold off and flex it a bit. This happened on my Puma...meow. Also, if you spray starter fluid around the manifold and the RPMs go up you have a leak. I know guys, I know, starter fluid is bad on the plastic manifold. It evaporates so quickly I don't think it hurts. And check the diaphragm like they suggested. If it still bogs or pops like SB said, it might be a leaned out mixture. Gently run the A/F screw in until it stops then back it out 2 1/2 turns.

[Alleyoop]

Where is it bogging from the get go just starting off or at higher speeds only?

Before attempting to adjust your carb always check for AIR LEAKS, now if you do have AIR LEAKS it will always bog when applying some throttle, starting off etc.. Start the motor get a Spray Bottle of water and at IDLE spray individual areas, if the idle changes when spraying you found an air leak.

Follow this procedure to adjust your carb for Fuel to Air mixture:
Alleyoop

scooterdoc.proboards.com/thread/1499/4ts-carb-tuning