stalls when quickly pullin the throttle

[noahnic]

I just put a 24mm Mikuni knock off on my flathead briggs, and it runs and idles great, but when I rapidly or aggressively pull the throttle it stalls. I can slowly open the throttle and it'll rev, but not if i pull it fast.
Does the carb need adjusting, or different jets or what?

 

[supernova]

Sounds like it needs more air mix. It should be adjustable even on a knock off.............:hammer:

 

[noahnic]

I think it is running a too rich, the spark plug was black when I checked it, also when I try to rev it, it backfires in the exhaust. I think it is missing at the higher rpms/more throttle.

Do you think the ignition could be part of the problem? I'm going to replace the plug, but could the coil need to be replaced?

 

[The Restore Kid]

I think it is running a too rich, the spark plug was black when I checked it, also when I try to rev it, it backfires in the exhaust. I think it is missing at the higher rpms/more throttle.

Do you think the ignition could be part of the problem? I'm going to replace the plug, but could the coil need to be replaced?

yeah a new plug can't hurt.. it does sound like it may be rich.. try shutting the fuel off and run it around until the carb runs out of fuel.. if it is rich you should be able to feel he motor start to run better for brief second before it dies completely.. if it's rich it will also blow black smoke...

 

[noahnic]

it doesn't blow black smoke, but at higher rpms it spits fire out of the exhaust pipe and pops and backfires a bit, the exhaust is a straight pipe about a foot long

i let it run out of gas and i don't think it ran any better, it wouldn't let me rev it past idle

 

[The Restore Kid]

It might be too lean also... I would even say exhaust valve needs work but if it ran right before ya switched the carb it is probably a matter of carb adjustment..

 

[jesse8931]

not enough fuel

 

[badtec]

I'm sure that a timing adjustment would probably help, but I had the same problem on an engine. I richened up the low speed jet, and it rocked. Scott.

 

[noahnic]

alright, I think it is definitely running rich, I moved the e-clip on the jet needle to the leanest notch and it is running better in the 25-75% throttle range. So I believe I need to get a smaller pilot jet and main jet to lean it out some more, correct? How can I tell what size I have now, and where can I get new jets for a 24mm mikuni clone?

 

[Chippytoo]

Hey, you ever get that carb running decent? I am thinking of getting one off of ebay and was wondering how it is working out for you.

Thanks