kart wont move

[Vtecmonster]

I have everything tightened down but the kart wont move. 45T sprocket and 10T clutch. The only thing i can think is wrong would be the clutch but its new. Under full throttle it wants to pull forward but doesnt. I dont smell the clutch burning either so that makes me think my diagnosis is wrong. Any and all help is appreciated.

 

[Texan]

Prop up the rear of the kart on block or bricks then give it a try.

 

[anickode]

You should be around a 6:1 ratio.

You are currently at 4.5:1, which given your tire size, would be doable with a torque converter. But not a centrifugal clutch.

 

[Tpdingo]

Try pumping up the tires well past their original spec(20 psi in a 10 psi tire). AFAIK, thjs should be safe for one or two tests, but DO NOT run this for normal use. With overpressure tires, put the kart on a driveway or a straight, no grade road and have a helper move the kart while you step on the gas. If it struggles but moves, the clutch is slipping bad.

 

[Vtecmonster]

Anickode, will you help me understand why the centrifugal clutch wouldnt work with this ratio. In my head even with the silliest ratio the kart should move even at a snails pace. Ive already dumped abt 400 in replacement parts and would rather not drop another $100+ on a TC. Thanks for your help.

 

[mckutzy]

On paper it should rip....
But as you can see it doesn't...
The usual ratio to start with is the 6:1...
You might be able to get away with a bigger sprocket, but your ground clearance will be real short...
A jack shaft might be on the order to help... You do have real estate to work with, and can be done with out welding, all bolt and clamp on...

 

[Tpdingo]

Anickode, will you help me understand why the centrifugal clutch wouldnt work with this ratio. In my head even with the silliest ratio the kart should move even at a snails pace. Ive already dumped abt 400 in replacement parts and would rather not drop another $100+ on a TC. Thanks for your help.

Here's a little tool I like that will help you too. The Go Kart Guru's Performance Program. Link here: http://gokartguru.com/images/Go_Kart_Drive_Line.htm

One of the points it measured was if the clutch will slip or not.

I plugged some approx numbers in for you, and the result...Smoking clutch.

 

[Vtecmonster]

Just curious but would engine modification play a role here? If so its has some stage 1 upgrades. Pipe, larger main jet, airbox delete, autolite sparkplug, governor delete, and stiffer valve springs. If i added a jackshaft what would i be looking for exactly? Recs on where and what size sprocket to buy.

---------- Post added at 05:12 PM ---------- Previous post was at 05:09 PM ----------

I revved the **** out of it trying to see if i smelled clutch and nothing. But i will look at the resource you provided. Thank you

Here's a little tool I like that will help you too. The Go Kart Guru's Performance Program. Link here: http://gokartguru.com/images/Go_Kart_Drive_Line.htm

One of the points it measured was if the clutch will slip or not.

I plugged some approx numbers in for you, and the result...Smoking clutch.

 

[Tpdingo]

A T/C will give you way more power and acceleration than a stage 1 will ever on a centri-clutch. You will end up spending more beating around the bush then you will just burning the bush with a flamethrower.

Also, if you really don't want to spend 100$ on a T/C, don't. Get a 60$ one instead!

This specific one is 70$ but you can get cheaper on other places

**Sidenote: what clutch are you using? When I was smoking my Hilliard clutch, it never smelled. It isn't a good signal for a slipping clutch.

**Sidenote 2: Let me help you understand what anickdote is saying. Most karts really require a 5:1 - 6:1 ratio. My kart at home runs a 3:1, but it also weighs 40lbs(100lbs with a 8 y/o on it) and has 9.5" tires. You have a likely 100+lbs kart with 13-15" tires on it. My clutch struggles to get me moving with 3HP. Your kart, well thats no game. Its all about the foot-pounds. My Dingo has 18 tires, so 9" from the axle. It takes maybe 10lbs of force to move it from the outside edge of the tire. That means it takes around 7.5 ft-lbs of torque to make it move on level ground w/ properly inflated tires. Well my T/C has a 3:1 ratio and my axle has a 6:1 ratio. It engages around 1800rpm, so you take the torque measurement from there. So lets say ~6 ft-lbs. 6*18 = 108 ft-lbs of torque @ 100rpm. That sends the kart flying up to speed in no time, and the T/C changes to get the wheels up to 600 rpm. Your clutch doesn't directly connect untl around 2600, so lets say due to slippage half the torque gets through. ~3 lbs of torque * 4.5 = 13.5lbs of torque. Remember that it takes 8 ft-lbs of torque WITHOUT the passenger. 2x - 3x the weight is 16-24 ft-lbs of torque and you are staying at a standstill all day.

 

[Vtecmonster]

clear as crystal. Thank you for the time and explanation. GPS is where i got my $100 number from. so, another thanks for the link. Dingos are pretty cool looking. A buddy had this kart just laying around and i have played with the predators a bit, albeit on smaller frames and i havent come across this issue since most of my builds were either mini bikes or one wheel peel karts with 60T sprockets. About $400 bucks later i was hoping to see a little money back with the cool albeit rusty setup it already had. I'll be lucky to break even. Thanks again tpdingo.

 

[anickode]

The Chinese ones are down to like $52 on eBay now. Still free shipping.

 

[Tpdingo]

clear as crystal. Thank you for the time and explanation. GPS is where i got my $100 number from. so, another thanks for the link. Dingos are pretty cool looking. A buddy had this kart just laying around and i have played with the predators a bit, albeit on smaller frames and i havent come across this issue since most of my builds were either mini bikes or one wheel peel karts with 60T sprockets. About $400 bucks later i was hoping to see a little money back with the cool albeit rusty setup it already had. I'll be lucky to break even. Thanks again tpdingo.

No problem. I remember when I did clutch gearing with my small kart that I converted it from 2 to 4 stroke. For your reference, it came stock with a 8:1 ratio, but wasnt a big deal because it could rev to 10K w/o fail so it moved(if the previous owner is tellimg me correcly)

 

[mckutzy]

Just curious but would engine modification play a role here? If so its has some stage 1 upgrades. Pipe, larger main jet, airbox delete, autolite sparkplug, governor delete, and stiffer valve springs. If i added a jackshaft what would i be looking for exactly? Recs on where and what size sprocket to buy.

Typically those modifications dont really do much... Especially the plug(it would need to be a built motor for real use of this type)....

Gov delete, helps to get more revs... Only to about 5K.. the springs should be left alone till a billet con-rod is installed to warrant an upgrade...
The stock spring will float just above 5K as to allow that as a gov, whereas the upgraded ones will rev quite past that, about the time the con-rod will rapidly self-destruct...

Exhaust, airfilter and re-jet(do a plug test and drill to size, to refine is the best method) are a good start... these typically all go together..

As for the jackshaft... youll need to fillout your profile to get a better idea of where abouts you are located, as to better suggest a location...
But a typical JS is just 2 sprockets, bearings and a support to hold the shaft... The sprockets are aligned to the clutch and drive sprocket on a plane that will work with both.....

Offhand a few sizes I calc'd are 12t-16t-30t-45t....

You can look up others if you wish, using a JS calculator like this one...
https://affordablegokarts.com/pages/gear-ratio-calculator

 

[Kansaskart]

Try pumping up the tires well past their original spec(20 psi in a 10 psi tire). AFAIK, thjs should be safe for one or two tests, but DO NOT run this for normal use. With overpressure tires, put the kart on a driveway or a straight, no grade road and have a helper move the kart while you step on the gas. If it struggles but moves, the clutch is slipping bad.

Holly cow! Lmao! That still doesn't isolate the issue as clutch related.

First things first, can you freely push this kart by hand? Meaning standing behind it, give it a shove will it roll or is it tight? It should easily roll. If not you have, most likely, a drive chain that is way too tight. Maybe not the best gearing but with such small wheels it should at least move some. Unless that clutch is a royal piece of work. There's other things, too. Bearings, brakes etc. If all checks out then spend money. My as well get the 60 tooth axle cause your just going to smoke clutches.

Agreed, a tc would be best. I use mine with a light kart, small tires and a 48 tooth no problem.

 

[landuse]

It is a gearing problem. I can guarantee you that. Even with a TC, at 4.5:1 you are still pushing the limit. I would get the TC with a 60T axle sprocket. You won't regret it

 

[Kansaskart]

It is a gearing problem. I can guarantee you that. Even with a TC, at 4.5:1 you are still pushing the limit. I would get the TC with a 60T axle sprocket. You won't regret it

I'd like to point out that lighter karts with smaller tires do ok with a 48 tooth I run them that way with no issues with a tc.

 

[landuse]

I'd like to point out that lighter karts with smaller tires do ok with a 48 tooth I run them that way with no issues with a tc.

I'm not saying it won't work, but in general karts are probably heavier than yours, and a ratio in the 4's wouldn't be something that I recommend right away unless the tyres are pretty small, which his aren't.

 

[Kansaskart]

I'm not saying it won't work, but in general karts are probably heavier than yours, and a ratio in the 4's wouldn't be something that I recommend right away unless the tyres are pretty small, which his aren't.

Right. And I'm not adding anything else till I wake up lol it's definitely Thursday lol.

 

[anickode]

:

I'd like to point out that lighter karts with smaller tires do ok with a 48 tooth I run them that way with no issues with a tc.

I run my small one that way. Light weight with a TC and 4.8:1 ratio.

But it's small and quite light. It's not a missile off the line, but it does pretty good.

 

[Vtecmonster]

thanks for all the advice guys. The 60T sprockets ive seen have a 9-3/4" dia. The tires i believe are 10" tall, so that doesnt leave much room for clearance. Not looking to break land speed records just want to move this buggy (running so i can max profit) to someones elses garage and cash out. The plan is to stick with my 45T and grab a TC. Yal think that will work?