How do you make a lawn mower (engine) fast enough for racing?

Question

and how fast can you actually make one go?

Answer 1

Gear ratios..  I dont think it will have good enough acceleration to be competative..  If its for a child and you  are really interested in racing you would really have to get a Comer 80 engine or something like that..  High rpm 2 stroke..  Lots of accel...

Answer 2

Nobody so far has given you the real answer because they obviously don't know.  The MOST important and first thing you should do is switch out the pulleys on the engine and transmission so that you achieve a larger drive ratio.  The main pulley on the transmission should be switched out for a smaller one.  One of the best places to find such a pulley is on the mower deck.  If desired, switch out the pulley on the engine that drives the main belt for a larger one.

After you do this, then you could start working on other things, like possibly getting larger tires & removing the muffler [I personally like doing this because it gives the engine a lot of grunt (you will not believe how loud it makes your engine)].

It is hard to say how fast your mower will go; each case is different, plus depending on which modifications you choose.  You should expect at least 40 mph or so, but this is no guarantee.

Remember in everything, safety first!  Good luck!

Answer 3

40+ mph if you want to spend a lot of money.

Sart off by using performance fuel additives and see if you can get a larger carberettor from an equivalent manufactures engine.

Take off unesseary parts like seat cut out mechanisms etc.

If you know someone ( or you if you can) fabrecate a larger exhaust, parts can be brought from specialist companies if you are going to spend big,

Answer 4

Well out here in Wisconsin we have lawn mower races and it's really kind of funny! But they take it very seriously! I've seen them go over 50mph which in my opinion is insane!

I don't know what you'd do to the engine, however I saw a lawn mower with a Subaru engine in it, I think it was from an Impreza!

Answer 5

The key to how fast you can go is the difference or lack there of between the sprocket on the engine/clutch and the sprocket on the axel.  the closer they are the faster the engine will move the (go cart).  Now the closer they are in size the less torque or take off speed you will have, but the higher top end speed you will have.  

40-50 mph would be tops.  

Now a chain saw engine would make one go faster.  More revolutions per second.