sprocket size help

[modedmuraytr2]

So I bought a 2002 murray track 2 for $150, the throttle has a connecting wire missing, there is no brake at all, chain is loose, starts to die a couple seconds after starting. I am working on fixing all that, and will be swapping engine with a 212cc preador in a couple months.

My question is I want to turn it into a speed demon, I am unsure how to remove the governor, and I want to change the sprockets because of rust and clutch does not sound right so I’m going to mabye change that. I don’t know what sprocket size is good for speed, and I don’t know how much rpm the sprockets will cause because the engine is old and I don’t want to go over 4700 rpm.

 

[mustangfrank]

So I bought a 2002 murray track 2 for $150, the throttle has a connecting wire missing, there is no brake at all, chain is loose, starts to die a couple seconds after starting. I am working on fixing all that, and will be swapping engine with a 212cc preador in a couple months.

My question is I want to turn it into a speed demon, I am unsure how to remove the governor, and I want to change the sprockets because of rust and clutch does not sound right so I’m going to mabye change that. I don’t know what sprocket size is good for speed, and I don’t know how much rpm the sprockets will cause because the engine is old and I don’t want to go over 4700 rpm.

I would suggest getting it running as-is and wait to change gearing until you have the larger engine in it. You'll be almost doubling the power and the gears you can pull with the new engine can be much taller (top speed) than with the stock 3.5hp.

This site and others have gear ratio calculators you can play with...
Go Kart Gear Ratio | Go Kart Speed Calculator Tool (gokartsupply.com)

 

[modedmuraytr2]

I would suggest getting it running as-is and wait to change gearing until you have the larger engine in it. You'll be almost doubling the power and the gears you can pull with the new engine can be much taller (top speed) than with the stock 3.5hp.

This site and others have gear ratio calculators you can play with...
Go Kart Gear Ratio | Go Kart Speed Calculator Tool (gokartsupply.com)

thank you for the feed back, I am currently going to trade the murray track 2 for a 14.5 hp 308cc briggs and stration, and I am going to put that on a doodle bug frame with a tourqe converter. it’s going to be a huge upgrade. I am also going to run a 10 tooth clutch and 60 tooth sprocket. do you want think this will be a good fast mini bike.

 

[mustangfrank]

A 6:1 ratio is pretty balanced, your tire size (height) will factor into that as well. Do your research on clutches, 14.5hp is outside the limits of the entry level TAVs. You might want to look at Comet 40 series or Juggernaut clutches.