5HP Bogs out when throttle is punched

I have a kart with a briggs on it and I just got it all tuned up, but when Im riding it and I punch it, it bogs out and I have to keep tapping the gas and put the choke back on and then I can feather the gas and it does fine. I just would like to know why it bogs when punched? I heard it could be the jet or a gasket? It has a Pulsa-Jet carb on it. Please help. :bowdown:


Well-Known Member
The pick-up tube on the Pulse-Jet have dirty screen or possibly the diaphragm is not functioning well. Does the Pulse-Jet have one or two tubes that dip down into the fuel tank?
It's the fuel mixture.. A lack of power BUT CAN GO wide open IF YOU MANAGE to get it there..

Means your fuel is too lean.. You need more gas in your air.. On a dual adjustable carb you'd wanna give it a little more idle fuel, to help punch it to the high end jet..

But on a Pulsejet, you're pretty well fcked.. You just pic what works best for ya and go with it.....

They kinda like to be a little to lean at idle, with no power, then kinda stumble and work to GET UP TO SPEED, like you are describing... If you CAN'T get it rolling, you'll want to give it just a little more fuel....

The RICHER you get the carb, the easier and better it'll start and run and go the lower end of the rpm range, but the piss poor design of the carburetor, has so much restriction, that when you get the engine up to a good screaming wide open speed, it loads up like a bitch because it's now to rich to go like a racer.....

You can get your screw set at one setting.. get the kart up to speed (half assed) until you get to like 3,000 rpms

THEN REACH BACK whilst the engine is running, and lean the fuel miixture screw out with your fingers as you're riding... And they will go pretty goood....

If you have the way newer Pulsejet with no mixture screw, you're pretty well screwed, as you can't adjust the fuel at all.....

Briggs pulsejets were designed for old women with rototillers.. If you want a motorcycle engine, buy a Honda CL350 of off craigslist for 600 bucks..


Well-Known Member
I doubt that there's nothing you can do to improve the current situation. Does your carb have the main jet (high speed) mixture screw? IMO, it should not bog that badly on throttle snap.
I got it to run but its just when I try to accelarate off the line it bogs out. after I rol at about 8 mph im good to go. I m thinking about puttin a motorcycle carb on there and welding a gravity fed tank. I also am putting a disc brake on it and its a single wheel drive so that will be fun... anyways thanks for the help guys.
Is the carburetor the adjustable carb, or non adjustable?? The adjustable carb will have a fuel metering screw with a nurled outer edge so you can turn it by finger, and has a spring locking it in place.. If it's adjustable all you have to do is screw that screw out a little bit, it will pull more fuel, and make more power..

If your carb is NON adjustable, the fuel screw will be a brass jet, predrilled for the size that Briggs says it should be.. It just screws in tight and there it is forever...

Sometimes, you can LOOSEN that jet up like a 1/3 of a turn, and that will cause an internal leak.. That helps if you can make it work just right... YOU HAVE TO!! destroy the threads, or fill them with thread locker or silicone or something, because if the jet is loose, it will just vibrate out and get lost...

I'd recomend silicone..... Screw the jet out a few turns, wad some silicone around it, screw it back in till it's tight, then back it off JUST a litle bit.. THEN rev it up and see how it sounds... Not enough, screw it out a little more... If it starts loading up screw it back in...

It was never meant to be an adjustment.. and it will go from working right but running lean, to leaking JUST A MOLECULE and running good, to a BIG leak and loading up and running like shit, all in a real tight spectrum... maybe 1/2 turn out from tight, and thats too far.. you're talking 5/32 or 11/123 or something goofy like that... Just exactly in the right spot, 1/3 out from tight, can save you buying a new jet sometimes....

Just remember to goober it up so it doesn't fall out.. :mellow: