Small Engines (Lawn Mowers, etc.): go kart/riding mower, input shaft, hp engine

Question
hello, I am 15 and am building a go kart. I really want this thing to go fast and have power. And I also want to get used to shifting since I will be driving next year. So I decided to use a riding mower transmission with a 12-15 hp engine.
#1- If I do use a transmission and re-gear it, will it go fast?(20-30mph)
#2-How big of an engine should I get?
Thanks very much!!!
-kevin

Answer
Hello Kevin:

1- What Kind of Transmission are you Going to Use? Depending on the Transmission, you can Replace the Pulley with a Smaller Pulley and Increase the Ground Speed. If you Use a Larger Pulley on the Engine than the One on the Transmission, it Increases the Rotations Per Minute of the Transmission Input Shaft and this Increases the Ground Speed. The Type of Transmission will Also Determine if you can Shift on the Fly. Most Mower Transmissions are Not Synchronized and you will Grind the Gears when Shifting Unless you Learn How to Synchronize the Transmission Using the Engine RPMs. 2- You can Use a 5-8 HP Engine and Get the Same Ground Speed that you will Get from a Larger (and Heaver) 12-15 HP Engine. It All Depends on the Pulleys on the Engine and Transmission. If you Hit a Snag or this Does Not Correct the Problem,  I am Here if You Require More Assistance. Hope this Helps. Let me Know What Happens, Please. May the All Mighty Bless You and Yours. Thanks.

Good Luck

Respectfully

John

PS: I am Allowed to Answer 10 Questions a Day. If you See I am Maxxed Out, then Try Submitting your Question at or Just After 8pm EST (US). My New Day Starts then. Thanks.

Respectfully

John