8 hp briggs carb

[jbruch694]

hey all,

i got an 8 hp briggs motor this weekend for free. it hadnt been started in like 10 years, and i got it running. it runs weird though, and i need help on tips of how to adjust it.

so it doesnt have a pullstart, and theres no electric start, for now ive managed with a socket attachment to a drill (which has partially ruined the drill) but its a dewalt so itll survive. anyway, this method of getting it started has worked. however, the adjustments are really screwed and i dont know how to go about fixing them.

i took apart the carb to clean it, but it was spotless, so i just shot it with a bit of carb cleaner for good measure. i put it back together, and located the 3 screws, one is on the bottim of the bowl at an angle, one is on the top of the carb, and of course one on the butterfly valve. i was told the one on the bottom of the carb is for high speed, the one on the top for low speed, etc. so i "reset" the tuning, i tightened the screws all the way and then undid them 1.5-2 turns. i tried to start it but it wouldnt go.

so i undid both screws like 1/2 a turn, and it fired right up and ran fairly consistently at 4,000 rpm (i have a tach attached). but it was running at 4,000 rpm with the butterfly pretty much 100% closed and the choke on, and when i opened the choke and butterfly valve, it sputtered and died, is this running really lean or what is it? it seems to be really touchy to any adjustment i give it. how can i make this thing run right? it seems like it is a good motor, and it ripped its way out of the screws i was holding it down with while testing it.

thanks!

 

[robbie]

Sounds like it's leaking a lot of air around the carburetor.

 

[jbruch694]

that could be it. i really havent checked the gaskets there, maybe ill replace them before doing anything else.

 

[Russ2251]

Open screws more to richen mix...gradually open choke to compensate.

 

[Doc Sprocket]

I still haven't nailed down a manual for mine, but when I tore the carb apart for cleaning, I counted the turns to seat each screw. Main was 1 3/4 turns out, low speed was 2 3/4 turns out. May not exactly match spec, but it did start and run. Still needs tweaking, but I haven't had time.

Edit- where are you? I've got a spare recoil assembly I'll likely never use...

 

[Bluethunder3320]

how did you get the carb apart? on my old 8hp (the first one) i couldnt get the carb apart. it opened a little then stopped halfway.

 

[jbruch694]

toystory - im in maryland, a pretty good distance away from ontario.

bluethunder - I took the three scrwes out on the top, and had the same issue you did. all i did was pull a bit harder though, and it came apart, nothing broke (astonishingly). i had an old Puch moped that did the same thing.

i may get around to trying these new ideas tonight, cause im off to school (on a sunday) to finish up building the set for my schools musical.

thanks!

 

[jbruch694]

oh, and i might just be able to get my hands on a 4 hp subaru robin motor, i was working with my friend and his dad on their monster trucks, "illuminator" and "screamin demon" and he has a little scooter with it on it he doesnt want.

 

[Doc Sprocket]

i couldnt get the carb apart. it opened a little then stopped halfway.

That's because (if you had the carb I think), you have to remove the high-speed jet first. It and the emulsion tube are one piece, and a good 2" long, going up thru the carb on an angle. Forcing it will bend it.

 

[Bluethunder3320]

Thanks, got it apart.