Stutter/Dead spot in motor

Lucky_7

Member
Got a weird issue during races where the motor will stutter once, more like a quick dead spot, then continue to gain rpm like normal. Its enough to unload the kart. This happened the week before as well, but it had multiple spots where the stutter was. I went to a smaller idle jet, 28 to 26, and now I get the single dead spot on exit while adding throttle, it was also less humid. I checked the fuel pump and noticed a lot of air in the supply line going from the pump to the carb, and when adding throttle I can see small air bubbles coming from the pump in the same line. Im going to try to seal the lines more later today but had a couple questions.

What kink of role does humidity play in tuning carbs, and should I change the idle jet to match air conditions?

How much air should be in the fuel line from the pump to carb, if any at all?

What do the small bubbles mean? Need to rebuild the pump, or get a new one?
 

Kart43

Member
A few bubbles in fuel will make no difference the carb draws from the supply in the bowl, a bubble of air does not stop fuel flow.
 

Lucky_7

Member
I've cleaned the carb and tried to get the motor to stutter again but it seemed fine. I'll see what happens at the track...
 

Jim46

Member
You will be better off controlling the bubbles, new fuel lines, if you have a tank with a pickup hose in it keep an eye on it
 
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