Low end power, possible clutch issue?

[DuckSoup]

Hey folks,

I picked up an old used go-kart that's been sitting for a while from someone. Managed to get the engine and everything working but now I'm having an issue with low end power and I suspect a clutch issue based on some of the research and reading that I've done online.

Basically, with the engine fully powered the clutch appears to not fully engage? I get this hissing sound while it's trying to engage (refer to the video) The go-kart tries to go a little bit but if I sit in it and give it the beans It goes nowhere on flat pavement.

I took a video just showing how it runs. If I lift the wheels off the ground the clutch engages and spins freely.

I'm not sure what the sprocket sizes are, my guess is a 60:10.

Just want to make sure I'm on the right track.

 

[Denny]

Nice safety shoes dude! Yea, clutch is bad. Tires may be too tall for gear ratio.

 

[Hellion]

What's the height of the rear tires?

Take apart the clutch and inspect. I'm dying to see what it looks like inside....

I'm not sure what the sprocket sizes are, my guess is a 60:10.

Well you need to COUNT the teeth and be accurate about it. Number of teeth on the clutch, number of teeth on the axle sprocket. This is no time for guessing, to be blunt.

I like your oversized clutch washer on the end.

 

[DuckSoup]

What's the height of the rear tires?

Take apart the clutch and inspect. I'm dying to see what it looks like inside....

Well you need to COUNT the teeth and be accurate about it. Number of teeth on the clutch, number of teeth on the axle sprocket. This is no time for guessing, to be blunt.

I like your oversized clutch washer on the end.

The rear tire is 14"

Also, you're right about the teeth count. It's the end of the day and I'm just getting tired and lazy.

Good call though because the clutch is a 13 tooth and the sprocket on the axle is 70. Going off the calculator that I've seen referenced on this site I might have a poor gear ratio.

 

[panchothedog]

Probably not worth the modification hassle needed to run a torque converter.
14" tall tires are the absolute limit height wise for using a centrifugal clutch.
If the rebuild works fine. If it burns out again after very little use, get a new clutch with a 10 tooth sprocket. It will make quite a difference in getting the kart to move from a dead stop.

 

[Hellion]

What kind of go kart is it? I’m always trying to build up my knowledge about classic karts.

 

[DuckSoup]

Probably not worth the modification hassle needed to run a torque converter.
14" tall tires are the absolute limit height wise for using a centrifugal clutch.
If the rebuild works fine. If it burns out again after very little use, get a new clutch with a 10 tooth sprocket. It will make quite a difference in getting the kart to move from a dead stop.

I was actually considering a torque converter as it seems like that's the way to go these days, but truthfully I don't know much about installing them. I'm still learning as I go with this thing. I'll look into the 10 tooth clutch and go from there. May end up doing a TC as well, just need to research the level of effort.

What kind of go kart is it? I’m always trying to build up my knowledge about classic karts.

So this is something I think this guy previously had welded together. I think it may have come as a kit, but it even has this formula looking body that goes with it.

I picked it up for cheap just because I wanted to get my hands dirty, fix an engine and see if I could get it running.

Has no brakes so I'll likely be installing a hydraulic kit from GoPowerSports.
The front wheels are both flat so I'll need to solve for that and the steering is quite loose, so that's something else I need to check out.
The engine was completely non-functional but after cleaning out the carb, getting rid of the old fuel and hooking up a new throttle cable, it runs pretty good now.

Wanted to see how far I could get with this thing then re-evaluate if I want to put some more power behind it with a new engine or modify it in other ways.

 

[Denny]

Is it an old promo kart? Their made cheaply from the start.

 

[DuckSoup]

Is it an old promo kart? Their made cheaply from the start.

Your guess is as good as mine, I just know the guy who had it had to weld it together himself.

It's using 1 inch steel tubing and if I could find my digital calipers I could tell you how thick. It seems sturdy enough even though some of the welds are a little spotty. :-D

Here is where I think they intended to put some brakes but just didn't get that far.

Rest of the welds look much better, there's just odd spots like that.

 

[Sparkwizard]

In my experience, I have come up with a formula for figuring gear ratios.
I measure the tire height in inches, divide by 2, then try to get as close as I can to that number.
Example: 14 inch tire divided by 2 would be seven. Try to get as close to 7:1 as you can.
An 84 tooth sprocket on the wheel and a 12 tooth clutch would make that kart much more fun and the clutch would be happier, too.
If you install a TC, you will smoke that tire unless you also step up and install a solid axle.
Just my opinion.

 

[DuckSoup]

In my experience, I have come up with a formula for figuring gear ratios.
I measure the tire height in inches, divide by 2, then try to get as close as I can to that number.
Example: 14 inch tire divided by 2 would be seven. Try to get as close to 7:1 as you can.
An 84 tooth sprocket on the wheel and a 12 tooth clutch would make that kart much more fun and the clutch would be happier, too.
If you install a TC, you will smoke that tire unless you also step up and install a solid axle.
Just my opinion.

Appreciate the feedback. When you say "Solid Axle" you mean one that drives both wheels instead of one? Is that essentially what's known as a live axle?

I was thinking of getting a 10T clutch from GoPowerSports and that would get me that 7:1 ratio for now. Looks like they have a couple options.

10T Hilliard Centrifugal Clutch 3/4" Bore, #420

Centrifugal Clutch fits most Go-karts with a 3/4 in. engine drive shaft and #41 or #420 chain. Manufactured by Hilliard Sprocket has 10 Teeth for chain size 41 and 420 Fits on 3/4" shaft Comes with 4 weights (shoes), "C" clips, bronze bushing and outer drum with sprocket

www.gopowersports.com

10T, 3/4" Bore, Centrifugal Clutch, #41/420

Designed to be used on one wheel karts with rear tires no larger than 15" tall, and engines 3hp-7hp. Centrifugal Clutch 10 tooth, 3/4" bore, used with #41/420/40 chain. Larger tires and live axles recommend using Torque-converter (part #218353)

www.gopowersports.com

 

[Sparkwizard]

Your chain looks like #35. The clutches you listed are for a much larger chain. (#41/420/40) are much larger links. Those clutches will not work with your chain or your wheel sprocket. That is why I suggested an 84 tooth on the wheel, because 12 tooth is the smallest #35 clutch I know about for a 3/4 inch engine PTO. Replace the clutch, chain and sprocket all at the same time so they break in together.

 

[DuckSoup]

Your chain looks like #35. The clutches you listed are for a much larger chain. (#41/420/40) are much larger links. Those clutches will not work with your chain or your wheel sprocket. That is why I suggested an 84 tooth on the wheel, because 12 tooth is the smallest #35 clutch I know about for a 3/4 inch engine PTO. Replace the clutch, chain and sprocket all at the same time so they break in together.

Ah, got it, thanks for calling that out. (I'm still learning here)

Thanks for the info, I'll do some more research and likely just replace all 3.

 

[Hellion]

That is [of course] not the original frame that goes with the Indy car body. How does it look with the body installed? I imagine you are sitting up rather high in the fiberglass body, but not sure.

I believe the original package was manufactured by F.W. & Associates as a promo car or light duty attention-getter.

Here's a few examples that have that exact style of body moulding:

No Reserve: Indy Car-Style Go-Kart Project

Bid for the chance to own a No Reserve: Indy Car-Style Go-Kart Project at auction with Bring a Trailer, the home of the best vintage and classic cars online. Lot #103,695.

bringatrailer.com

No Reserve: F.W. and Associates Pennzoil Indy Car Replica Go-Kart & Memorabilia Collection

Bid for the chance to own a No Reserve: F.W. and Associates Pennzoil Indy Car Replica Go-Kart & Memorabilia Collection at auction with Bring a Trailer, the home of the best vintage and classic cars online. Lot #194,691.

bringatrailer.com

Pretty sure he meant live axle when he mentioned "you will smoke that tire". You can still smoke the tire with a regular clutch since there is very little load or weight to overcome with a dead axle, one wheel drive, one-wheel-peel axle. Basically impossible to burn-out with a live axle. Looks like you already have a live axle since I see a bearing hanger in the above photo.

If you can weld and fabricate it would be a challenge to make another chassis that has the right ground clearance and "look".

 

[DuckSoup]

That is [of course] not the original frame that goes with the Indy car body. How does it look with the body installed? I imagine you are sitting up rather high in the fiberglass body, but not sure.

I believe the original package was manufactured by F.W. & Associates as a promo car or light duty attention-getter.

Here's a few examples that have that exact style of body moulding:

No Reserve: Indy Car-Style Go-Kart Project

Bid for the chance to own a No Reserve: Indy Car-Style Go-Kart Project at auction with Bring a Trailer, the home of the best vintage and classic cars online. Lot #103,695.

bringatrailer.com

No Reserve: F.W. and Associates Pennzoil Indy Car Replica Go-Kart & Memorabilia Collection

Bid for the chance to own a No Reserve: F.W. and Associates Pennzoil Indy Car Replica Go-Kart & Memorabilia Collection at auction with Bring a Trailer, the home of the best vintage and classic cars online. Lot #194,691.

bringatrailer.com

View attachment 156345


Pretty sure he meant live axle when he mentioned "you will smoke that tire". You can still smoke the tire with a regular clutch since there is very little load or weight to overcome with a dead axle, one wheel drive, one-wheel-peel axle. Basically impossible to burn-out with a live axle. Looks like you already have a live axle since I see a bearing hanger in the above photo.

If you can weld and fabricate it would be a challenge to make another chassis that has the right ground clearance and "look".

Huh, that's awesome you found that. I'm not sure what their plan was with this setup. I actually haven't tried mounting the body on yet as I've been still trying to get it working. The body isn't super important to me though, just having something that works and learn from for the fun of it.

We have a karting track just down the road that lets you bring home projects too, so I thought it would be fun to get this little guy working and maybe take it there. Lots of work to be done still.

 

[Hellion]

The body isn't super important to me though, just having something that works and learn from for the fun of it.

Then sell the body for big bucks and keep the frame as your "learning test bed". I think it has the makings of a good off-roader with that ground clearance. The previous owner didn't skimp with the Azusa Tri-Star wheels, those are fancy.

Does it indeed have a live axle (both rear wheels joined together and turning as one)?

 

[DuckSoup]

Then sell the body for big bucks and keep the frame as your "learning test bed". I think it has the makings of a good off-roader with that ground clearance. The previous owner didn't skimp with the Azusa Tri-Star wheels, those are fancy.

Does it indeed have a live axle (both rear wheels joined together and turning as one)?

Not a bad idea, I'll see what I can get for the body assuming it doesn't fit. Maybe I can ask for a few hundred or something.

The front two wheels are flat, not sure if I can repair those or if I just need to replace them.
The rear wheels I suppose I could keep though maybe going slightly smaller would help with some of the gearing ratio unless I just replace the sprocket, chain, and clutch.

It does not have a live axle. The left wheel drives and the right rear can spin independently.

My hope is that maybe with the extra space in the back, I could throw a larger predator engine on it to get some more speed.

 

[Hellion]

The front two wheels are flat, not sure if I can repair those or if I just need to replace them.

Try some air first. They are split rims so they take an inner tube. Inner tubes are infinitely patchable (to a point). Best to have several spare inner tubes.

I could throw a larger predator engine on it to get some more speed.

Bigger engine does not mean more speed, it means more torque and more 'oomph' for moving fat people lol. All Predators are governed to 3600 revs maximum. Removing or adjusting the governor (wow what a concept) to attain a higher engine speed, plus gearing, determines vehicle speed.

 

[DuckSoup]

Try some air first. They are split rims so they take an inner tube. Inner tubes are infinitely patchable (to a point). Best to have several spare inner tubes.



Bigger engine does not mean more speed, it means more torque and more 'oomph' for moving fat people lol. All Predators are governed to 3600 revs maximum. Removing or adjusting the governor (wow what a concept) to attain a higher engine speed, plus gearing, determines vehicle speed.

Tried the air approach, it was coming out faster than I could put it in. :-D

Good call on the inner tube, I didn't know it had those. I'll crack it apart and see what we've got in there, thank you for that.

On the engine size, I've been playing with that kart calculator just plugging in numbers. I'm seeing that I can potentially run a gear ratio that supports a higher top speed with a stronger engine. Combined with a TC you can get some pretty good performance. But this is making a lot of assumptions on my part and may not be reality.

 

[Denny]

That chassis is definitely a home brew. If you can weld you can do anything.