go cart speed

#1
Ive started building a go cart out of some scrap metal and lawn mower parts. Im almost done, i just need to get another spool of wire for my welder so i can make a mounting plate for the motor. i was wondering how fast it might go. im putting a 2 cylinder 18 horsepower briggs on it with a 5 inch pulley on the motor and a 3 inch pulley on the axle.
 
#2
it wont go anywhere with those size pullys. 3 on the engine and 5 on the axle might work but you say your using pullys and a belt and not a chain? My experience with pullys is that they suck. If you can get it up to speed with the 5 on the engine and 3 on the axle it depends on how big your wheels are too but youll be pushin 70 id say but youd have no low end power and slip the clutch alot. Not to mention its extremely dangerous with lawn mower parts. i hope your building in a stout roll cage aswell :) Post some pics
 
#4
what kind of tranny does it have? a 5 on the engine and a 3 on the tranny will make you FLY as long as you change out the tranny lube to a thinner viscosity, and take the reverse chain out of the tranny so it dosent explode and destroy your tranny.
 
#5
i am not using a tranny.I am going to put a electric clutch from a mower deck on the motor and have a belt going right from that to a pulley on the axel. what size gear should i put on the axel and still keep a 5 inch pulley on the engine. i want it to go somewhat fast but still have a little low end power. i think the tire size is 12x10-8. thanks for the help.
 
#6
you need a bigger pully on the axle than on the engine for sure but youll probrobly need to expeariment to find the right speed you want. It has an electric clutch? how does that work iv never come across anything like that
 
#7
well using an electric clutch is a BAD idea for a lot of reasons:
#1 electric clutches can only be engauged or disengauged, so once you hit the clutch switch, its going to either snap your belt, flip the whole cart over, or stall your engine depending on your gearing. if you are planning on using a tall-ratio belt drive you will need a manual clutch so you can ease the clutch in yourself to prevent engine stalling or flipping right over. trust me, lots of people try to use an electric clutch on a racing mower, and it has NEVER worked...
 
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