G 16 yamaha

[Chubbers]

Hi All new guy here! I just bought a Yamaha g16 and when its pedal to the metal it runs fine. When starting it sputters and backfires occasionally .
I have changed the carb fuel pump and filter. I cant figure out how to adjust the settings with the air box on so am trying to adjust with it off. I read in the forums that it will misfire with the airbox off. I have left the settings in the same position as the old carb. Still jerky performance at low speed.

[crash12888]

More than likely the low speed fuel circuit is clogged and you need to pull the carb and soak/clean it.
While you are at it go ahead and adjust the valves while cold.

[pilotdane]

You said you replaced the carburetor. What did you replace it with specifically? Was is a genuine Mikuni or a clone? If it was a inexpensive clone I have run into several that just don't run right and they can't be adjusted to work properly.

[rstacy]

Originally Posted by pilotdane

You said you replaced the carburetor. What did you replace it with specifically? Was is a genuine Mikuni or a clone? If it was a inexpensive clone I have run into several that just don't run right and they can't be adjusted to work properly.

Exactly. What did you pay for the new carb?

A G16 will run without the airbox but you will need to restrict the airflow by choking it.
There isn't much to adjust on the carb. The pilot screw should be out 1.5-2 turns. That's it.

[crash12888]

Ok, I read Carb fuel pump not carb, fuel pump.
Yep, go back to the oem carb and give it a good carb cleaner soak/clean/blow

[Chubbers]

i put humpty back together and added seafoam to the gas --still a fartin cartin
the carb was an oem replacement so thinking maybe a linkage problem
Any ideas
Took it up the road and under full throttle it seems to run ok
Low speed jerky like on and off

[Chubbers]

The carb was with the cart when i bought it --Pretty much identical to the old one , however the problem is the same old carb new carb
Got a fartin cartin

[crash12888]

Originally Posted by Chubbers

i put humpty back together and added seafoam to the gas --still a fartin cartin
the carb was an oem replacement so thinking maybe a linkage problem
Any ideas
Took it up the road and under full throttle it seems to run ok
Low speed jerky like on and off

With that statement, I'm betting the throttle is opening way before the micro is energizing the starter making the slow speed travel actually coming from the micro going off and on.
Take a close look at your carb butterfly, with the key off slowly push the gas pedal until you hear the micro "click", your throttle butterfly should just start to open right after the click.
If it opens before the click you will have half throttle when starting and the issue you describe.

[Chubbers]

That makes a lot of sense i will go back in. So then i just have to adjust the throttle cable then correct? Any ideas where the micro switch is located on a Yamaha g16
I just pulled it apart again and the throttle is 1/2 open when the pedal is at rest i tried to adjust the cable but cant get the throttle plate to close fully when stopped. Thinking this may be the problem

[Chubbers]

Should the throttle butterfly be partially open at rest mine id about 25% open \