off road gokart

[questseeker]

have 139cc 2stroke motor want to hook up to cvt what would be the best

 

[landuse]

You are going to have to give us a lot more info than that to give you a hand. Is this going on a kart? Where are you planning on riding? Have you got pics? How much does your kart weigh? Are you asking what CVT will be the best, or the best way to hook one up?

 

[questseeker]

we are driving on gravel roads right now with 5.5 4 strokes speeds of 40 mph+ .drives have been changed for larger drive gear for better hole shot my cart weight is aprox 100 lb we drift left racing. these are off shore carts that we mod wheel base stock is 4 ft width 3ft . few straight a ways regarding cvt looking at best way to mount and what cvt to use for best out of the hole shot. mounting i can figure out will be custom this is what the carts look like and how we drive them some carts have already been mod on length and width we only have one disk brace and it is on drive axle we are using 40 pitch chain now one mod cart is using 32 pitch this is a cart that was striped and built from frame up. using racing cart axles this made cart wider and longer but also gave better stability

 

[Doc Sprocket]

Tell us more about he current drive train? Can we assume there is a centrifugal clutch used? How many teeth on the clutch sprocket, and how many on the axle. What is the overall diameter of the rear tire?

 

[fowler]

what is this 139cc 2 stroke
what was its past use?
what is the shaft diamiter?


the only concer major i see is the engagement speed

 

[questseeker]

regarding centrifugal clutch 13 teeth drive sprocket 54 teeth tires are 3,5 wide 5 in high motor was a snow thrower Tecumseh it was neglected and dis respected needs new carb not issue shaft diameter not an issue as have lathe to turn to size and enough material to work with

 

[Doc Sprocket]

What is the overall diameter of the rear tire?

Do you know this measurement? Also- do you know what speed (RPM) the engine is maxing out at?

 

[questseeker]

13 inches tire rpm around 5thou

 

[Doc Sprocket]

Cool. If you put a Comet 30 or TAV2 on there, your top speed with current gearing should increase by upwards of 10%, thanks to the 0.90:1 overdrive of the unit. At 5k, your kart theoretically tops out around 42MPH...

 

[questseeker]

these are mod engine also no governor emulsion tubes changed fuel pumps intakes ported straight exhaust 1 ft max on exhaust pipe no muffler heavy valve springs

 

[questseeker]

this will require a jack shaft or not thanks toy story

 

[Doc Sprocket]

The TAV2 is a self-contained, "1-piece" unit that has it's own, built-in jackshaft. The Comet 30 (IIRC) requires a separate jackshaft assembly. Basically, when you're shopping for a CVT, it should be pretty obvious whether the unit you're looking at has a back plate that bolts to the engine or not.

 

[Bluethunder3320]

heavy valve springs

2 strokes dont have valves. you sure?


the comet 30 (i think) doesnt have a backplate. mine has a plate that bolts between the engine and frame.

TAV2 has backplate that bolts on the engine.

http://www.bmikarts.com/item/Comet-TAV2-Torque-Converter-218352-218353-218354-or-218355-646

 

[Mrpinhead11]

do u have a pic of the engine?

 

[Doc Sprocket]

2 strokes dont have valves. you sure?

I skimmed his post so fast I missed that!!!

EDIT- The top pic is blurry as he//, but back end of engine looks like stock GX/Clone- see the black squares?

 

[questseeker]

right now we are running 5.5 4strokes also where to get said cvt all places out of states wll not ship to canada

 

[Doc Sprocket]

Wherabouts in Canada?
Try here, maybe? I've never used them, just did a search. http://www.ubuilditplans.com/NEWUBUILDIT.HTML#40

 

[questseeker]

if i would go to 16 in would i get a better hole shot with a tvc

 

[questseeker]

how do i figure rpm for 138 cc two stroke i am planing on no governor running 13 drive centrifugal clutch secondary54 drive tires are 13 in and what would be max speed with this set up

 

[Doc Sprocket]

You can't "figure" the RPM for that. You can guess, and that's about it. Most likely, you will be looking at 5000 on an otherwise stock engine IF your gearing allows it- Which, at 4:1, it will not.