Go kart sprocket too close to ground

[bladeZjack]

Okay thank you. I’ll go ahead and purchase the tires. I’m posting photos of the sprocket I removed. I’m planning to use a split sprocket for easier installation/removal. I saw some sprockets on GoPowersports. It looks like the shape will fit. I don’t see any specs on the website. Just the tooth numbers. I could call them and get the specs. I’m planning to purchase an identical 72 tooth replacement. In case the tire change doesn’t work out or I wanna keep the original tires. I will need a split sprocket that’s 2 inches smaller in diameter than the one I currently have to be 1 inch higher to the ground. How does the smaller sprocket affect the performance? Faster speed, less torque? Or slower speed, more torque?
Thank you.

 

[Hellion]

How does the smaller sprocket affect the performance? Faster speed, less torque? Or slower speed, more torque?

https://www.gokartguide.com/gear-ratio-chart-speed-calculator/

Try this speed calculator. Enter the drive tire diameter, tooth count on your clutch and the expected size (tooth count) of the axle sprocket you're looking to buy and you can see the speed change as the sprocket gets smaller/larger. EDIT: you have to have a good gear ratio or you either won't move or the engine will be over-revving but you won't be going very fast.

The calculator is interactive so you can drag the red sliders instead of entering data.

 

[bladeZjack]

Hello everyone,
I finally have some free time to get back to working on my go kart. I’m gonna go with using a smaller sprocket first. The sprocket that I have now is 8.5 inch in diameter. It sits too close to the ground. If I want to increase my ground clearance by an inch, I would need a sprocket that’s 6.5 inch in diameter right?

 

[ezcome-ezgo]

It will massively impact your gear ratio to shrink the sprocket that much. Have you concluded what the ratio will be using the calculator Hellion suggested?

 

[bladeZjack]

Thank you for mentioning that. I will recheck the the ratio using the calculator. But am I right with using a 6.5 diameter sprocket increasing my clearance by an inch? Or will a 7.5 inch diameter sprocket increase my clearance by an inch?

 

[Hellion]

A 7.5 inch sprocket is exactly 1 inch smaller than 8.5 inch. The 6.5 is 2 inches smaller (than 8.5). When you measure it, like your photo in post #23, put the ruler directly across the center. Your ruler is placed slightly above the centerline.

Don't forget to count your teeth! I mark the starting point on mine, like with a magic marker (Sharpie) and then count. Then I usually write the tooth count right on the sprocket.

 

[bladeZjack]

I only have the 8.5 original sprocket. I’m actually just doing some head calculations on what would increase my clearance by an inch. Will using a 7.5 inch diameter sprocket increase my clearance by an inch? Or will a 8.5 inch sprocket increase my clearance by an inch?

 

[bladeZjack]

Sorry typo:
I only have the 8.5 original sprocket. I’m actually just doing some head calculations on what would increase my clearance by an inch. Will using a 7.5 inch diameter sprocket increase my clearance by an inch? Or will a 6.5 inch sprocket increase my clearance by an inch?

 

[Master Hack]

If yer original sprocket 8.5 and you buy 7.5 your clearance will increase by one half inch. Yer gear ratio will be all honked up. You would need to reduce the drive sprocket by a bunch. The problem is finding one small enough. Sprockets are labled by tooth count.
if you proved that info, we could give ya better info.
maybe l missed it but, l don’t see an actual measurement other than “vert close” to the ground. Has any one suggested a guard or skid plate or other proctive device? Sounds like it would be an easier solution.

 

[Edwin Spangler]

If yer original sprocket 8.5 and you buy 7.5 your clearance will increase by one half inch. Yer gear ratio will be all honked up. You would need to reduce the drive sprocket by a bunch. The problem is finding one small enough. Sprockets are labled by tooth count.
if you proved that info, we could give ya better info.
maybe l missed it but, l don’t see an actual measurement other than “vert close” to the ground. Has any one suggested a guard or skid plate or other proctive device? Sounds like it would be an easier solution.

 

[Edwin Spangler]

Obviously its cleaned up and looking better than that...

 

[Hellion]

Where’s the pics? I want to see the new tires/wheels mounted up and the ground clearance they provide for the original sprocket.

As long as there’s some ground clearance, and the sprocket isn’t actually rolling on the ground acting like a 3rd wheel, it’ll be fine. I don’t think we addressed what is acceptable clearance or not. You should probably keep in mind that kart tracks are a lot more consistent than your undulating neighborhood street with ripples, dips and patched potholes.

If yer original sprocket 8.5 and you buy 7.5 your clearance will increase by one half inch.…

He’s right. Overlapping the 8.5” and 7.5“ sprockets center to center nets you a mere half inch of clearance. The 7.5” is a half inch smaller all the way around.

 

[bladeZjack]

Thank you all for confirming my inquiry about the sprocket size and clearance situation. I called GoPowersports about needing a 7.5 inch sprocket but unfortunately their inventory details doesn’t show the diameter of the sprockets, just the tooth count. I currently have a 72 count sprocket and it’s 8.5 inch. What tooth count should I get that would be around 7.5 inch? Attached photo of the type of sprocket I plan to purchase. Thank you!

 

[Hellion]

Is the chain you are using #35? If not, what is it? I bet Master Hack has some clever math to determine diameter with tooth count....

 

[Master Hack]

Apparantly he didn't hear anything that was said.
The only cleave formula is to ditch the diameter thing. I suppose you could take circumferance divided by pitch.
Or look it up here.
Nitrochain.com
I'm done he's not listining.

 

[bladeZjack]

Yes I’m using a #35 chain. Thanks.

 

[Master Hack]

Just BTW, Circumfrence divided pitch is about right. Get ya purdy close.
6.5 x 3.1417= 20.421/.375=54.4556 so ya gots to cut one half tooth off.

 

[Denny]

A 72 tooth sprocket should be right for your kart. With a 12 tooth clutch.

 

[anderkart]

Yes I’m using a #35 chain. Thanks.

 

[Hellion]

A 72 tooth sprocket should be right for your kart. With a 12 tooth clutch.

That's the axle sprocket he originally had. We've been going around in circles for a while and have come full circle.

How does the smaller sprocket affect the performance? Faster speed, less torque? Or slower speed, more torque?

Of course with the calculator I provided in post #22, you can mess around with gear ratios for sprockets that you do not even own to get the top speed for those gears, provided you know your engine's top RPM as well.... but ratio calculators don't tell you anything about acceleration: