The motorcyc!e is a 1957 Model B Hummer, 125cc.
The engine idles real nice, revs up as it should so all is fine there.
The problem is on the drive, the motorcycle gains speed very nicely up to a point.
Maybe about 30 MPH and then the exhaust pipe emits a sort of a rapppp pappp pappp noise, the engine will not gain any more speed.
I easily let out of the throttle and then the engine begins to run at an easier pace and will sort of begin to gain some RPMs.
This tells Me that the fuel condition is on the lean side and needs to be enrichened.
I pull over and give the main jet adjusting screw an 1/8th of a turn out , counter clockwise, and then those same conditions are met at a much lower engine speed, Me thinking that by screwing outwards on the main adjustment needle would enrichen the fuel mixture.
Stopping the bike, screw the main back in to where it was and ride off being satisfied that maybe this is the best it will be.
One thing I did fail to mention, the main adjusting screw is 1/4 of a turn from being fully seated.
I am a little fearful of going in too far with the main adjusting needle and causing a much leaner burn and possibly scorching a holenin the piston.
Am I wrong in My thinking that running the needle screw, clockwise, and closing down the jet will lean out the fuel mixture ?
Is there a work around on getting the engine to gain more revs without seeming to run out of gas ?
I probably can not get a video of the motorcycle in motion but maybe I can somehow get a sound recording of what it sounds like. Maybe the wifey can get a recording of it when I ride past Her. Be later today though.