modifying lawnmower engine...

[Rubber314Chicken]

does anyone know what is a standard rpm that lawnmowers run at? and the little thingie on the carburetor (like a pentagon on the top) adjusts rpm, right, not the mixture (that is a screw, right)

 

[borat_sagdiyev]

Reduce the size of the sprocket on the engine and this will increase the rpm's of the transmission input shaft

found that on some website

 

[Rubber314Chicken]

Yeah, I know that, but I want to be able to have a throttle control (a pedal), becuase me and my friend are making a go cart...

 

[bullzi]

lawn mower engines are the exact same as gocart engines, the only thing is that lawnmower engines are vertical not horizontal, if you are going to run a lawnmower engine on its side, it will not work, the oil will not flow right in the engine,

im no trying to be a fag by saying this, but if you dont know where the throttle adjustment is on the carb, maybe a little more research would be better before building one, because if you dont know this chances are there are more things you dont know..., just somethin to think about, but if you ever have any questions about gocarts let me know, my dad and i have built 10, 5 of which are racing and go 65mph (clocked with a radar gun)

as far as this carburetor goes, i need to know who makes the engine, should be briggs and stratton, robin, tecumseh or something like that, also, was it vertical? (meaning was it mounted in the lawnmower with the shaft pointing down, horizontal is when the shaft is horizontal) i need to know this so i can help you out

 

[bullzi]

Reduce the size of the sprocket on the engine and this will increase the rpm's of the transmission input shaft

found that on some website

wow, that website is wrong.. you would want the sprocket on the transmission smaller, and the sprocket on the engine bigger, but that wouldnt work for a gocart

 

[Rubber314Chicken]

Yeah, I know that the engine wouldn't work right on its side (but my friend nor my dad don't)

Here is some info off the side of the engine:
Sears Roebuck, And Co.
Model #: 143.986002
Family: STP185ULGIRA
Displacement: 186
D.O.M. 8103D


There is a little spring loaded torx screw on the side of the carb, I'm guessing that is the mixture, and the pentagon spring loaded thing is the throttle, becuase it has holes to attach cables and such.

 

[bullzi]

ya, and if you can take the air filter off and look inside, try moving the one that you think is the throttle and see if you can see the little metal disc inside the carb opening up or not, if not, then its somethin else on the carb

 

[Furby123]

Sounds like a fun thing to do.

 

[CompMan]

Cut the muffler off lol.

 

[Rubber314Chicken]

Cut the muffler off lol.

yeah, its a bolt on directly to the exhaust valve, so that would create issues with crap getting in the engine, but we might rig something...


edit- and yeah that is the throttle and the scree is the idle adjust. any idea what the rpm could be?