Briggs Model 91202?? Mine Bike Exhaust

Mini Bike & Go-Kart Parts

#1
Hey everyone!!
So building a mini bike with my son and this place has been the upmost of helpful with information during this build. Have run into another question.

does anyone have experience with this motor? I have one and it didn’t come with any exhaust on it. Does anyone have any information on a head pipe for this bike or an exhaust? I got a flathead pipe but it’s too big.
Any help is greatly appreciated! Thanks
 

Harquebus

Active Member
#2
I think that's a 3.5 horsepower.

If the exhaust port is threaded, you know what to do... 1/2" threaded iron pipe and a Briggs #89966 hot dog muffler.
EDIT--otherwise, something custom made welded together...
 
#3
I think that's a 3.5 horsepower.

If the exhaust port is threaded, you know what to do... 1/2" threaded iron pipe and a Briggs #89966 hot dog muffler.
EDIT--otherwise, something custom made welded together...
it is threaded. But has flange holes as well. A piece of 1/2” threaded iron will thread into there??
 

Harquebus

Active Member
#4
it is threaded. But has flange holes as well. A piece of 1/2” threaded iron will thread into there??
I think that's the size. Plus the aforementioned "hot dog" muffler will screw right in.
I'm not really sure now. All I have is a few 3 HP Briggsies, not a 3.5. :D

For a flange exhaust pipe, you could find a large steel washer that has a 1/2" hole in it but also covers the flange holes. Drill the holes for the flange screws, then weld a pipe onto the washer of the desired length.

I like that hot dog muffler though. Flows well enough but tones down that braaap braaap of the raw exhaust.
 
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#6
So I got the hot dog muffler on there and all is well with that. However, upon firing it, it'll just stumble for a couple of second and the goes wide open. The throttle is of no effect. Just runs wide open until I pull the plug wire. I've strongly considered ditching the onboard gas tank and carb combo, but can't seem to find an intake for it. Any idea why it would just run wide open? or have an idea where I can find the right intake to put an aftermarket carb on it?
 
#7
Yay! Great success.

Any idea why it would just run wide open? or have an idea where I can find the right intake to put an aftermarket carb on it?
Uh, could it be that the idle screw is turned in all the way {thereby keeping the throttle butterfly open}?
Do you have a throttle return spring hooked up or is the throttle just swinging in the breeze like a barn door?

Make sure everything is operating the way it's supposed to.

As for a custom intake, it can be made the same way I instructed you on making a custom exhaust header. Tubing, sheet metal for flanges, a drill and a decent welder. There might be forum members who can fab one up for you.
 
#8
Yay! Great success.



Uh, could it be that the idle screw is turned in all the way {thereby keeping the throttle butterfly open}?
Do you have a throttle return spring hooked up or is the throttle just swinging in the breeze like a barn door?

Make sure everything is operating the way it's supposed to.

As for a custom intake, it can be made the same way I instructed you on making a custom exhaust header. Tubing, sheet metal for flanges, a drill and a decent welder. There might be forum members who can fab one up for you.

This is great information! Everything appears to be operating as its supposed to. I'll check the idle screw and make sure its not closed all the way.

As for someone that can fab up the intake, I'd be open to someone being able to fab one. Or I may try to tackle it myself. I'm determined to get this Briggs running right lol, I dont' want to take the easy way and just go get a predator. This is more of a challenge and more entertaining.
 

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