New purchase Kart with 420cc Predator Belt Issues

[MaidenInk]

I'd like to say hello to everyone! I am brand new to the go kart game, but I do learn pretty quickly. A few weeks ago a picked up a few go karts for me and my kids to have some fun with, The first two I picked up were basic plain jane 6.5 horse karts. One is a Yerf Dog and the other is an American Sportworks kart. Put new belts on them, new 3 point seat belts and tires and they seem to be rolling along just fine.

Now enter kart number 3 that I picked up more for me and my two oldest kids. The previous owner bought and installed a predator 420 on it. Once he got it assembled he said it kicked the belt off. So he purchased another belt, same result. After 3 tires he gave up on it, and well now it's mine. Here is a couple of pictures of the set up. Can anyone give me any ideas of what I should do here? Basically I have not done anything at all yet, I didn't want to just start throwing parts at it until I got some input from other people who know more than me Yes I realize the center bolt is out, I just took it out to pull the assembly off just to look around a bit.

Thank you all in advance,
MaidenInk

 

[Denny]

The driver clutch is on backwards for starters. You might really want to go to gokart supply website and do some research. I can see a lot wrong with your set up. It looks like it is a 30 series but I can’t tell for sure. You will be able to with some research though. Hope this helps.

 

[MaidenInk]

The driver clutch is on backwards for starters. You might really want to go to gokart supply website and do some research. I can see a lot wrong with your set up. It looks like it is a 30 series but I can’t tell for sure. You will be able to with some research though. Hope this helps.

What else is wrong with the setup? If you take the driver pulley off and flip it, then then belt doesn't line up anymore. That's why I posted it here to see if anyone had any ideas. I am assuming I am gonna have to buy some parts, that's no problem. I was going to just order a complete 40 series set up, so I know what I am dealing with. But before I did that I figured I am probably not the only person to have ever run into this.

 

[Bansil]

Welcome, you mentioned 3 pnt belts. Do they have rollcages on them? If NOT remove belts you want your kids flung away and not attached to kart if it flips. If they have rollcages then you have to have belts to keep them in and safe..disclaimer.....do research before you heed my warning...its for the childrenzs

 

[MaidenInk]

Welcome, you mentioned 3 pnt belts. Do they have rollcages on them? If NOT remove belts you want your kids flung away and not attached to kart if it flips. If they have rollcages then you have to have belts to keep them in and safe..disclaimer.....do research before you heed my warning...its for the childrenzs

I wouldn't exactly call them NHRA legal, but yes they have overhead bars.

 

[Denny]

With that plate for the cvt and where the sprocket is it will never line up. To fix it right you will have to upgrade to a 40series you are correct about that. The absolutely best advice, anybody, anywhere can give you is do the research. The website I gave you will tell you why, how and when to install, modify, measure the cvt system for maximum success. What size sprockets are on the kart (tooth count)? What size rear tires are on it? What is the approximate weight of the kart, the passengers. These are all the things you need to know. Right now you need to know what you are talking about so you can know what we are talking about. You need to know what questions to ask us. Please go to the Gokart Supply site and look up CVT’s. That is the best we can do for you. You can weld can’t you? You will probably need to do that too.

 

[karl]

To fix it right you will have to upgrade to a 40series

He already has a 40 series, this is not good advise. Could cause someone to waste a couple hundred bucks.
Not trying to be rude, but it is quite easy to tell a 40 series from a 30, if you are familiar with this stuff.

The driver clutch is on backwards for starters.

Nope, bad advise again. The driven clutch has the red spring, not yellow. Its on the "right" way.

What else is wrong with the setup?

The backplate 40 series is inherently flawed , sorry you bought someone else's mistake.

That's why GPS won't sell it on ebay, they can't control the feedback, same with the juggernaut clutch.

The 40 series was designed to run with the driven opposite of yours, hence why its driver is "backwards"

If the driven if mounted outboard, like yours, it needs to float on a proper jackshaft the width of the belt, with
the yellow reverse wound spring. But the backplate setup does not allow this, that is why it is flawed.

The "fix" is to flip the driven, like your setup, but is not how the clutch is supposed to work.

Hence it's a "get what it is" situation.

Many are in denial and cannot admit their cart/ drag bike could possibly be flawed,
and after spending GPS money on their clutch setup, have too much pride to be capable of accepting this.

So just be aware, some will say "its just fine" but burn multiple belts a year and don't realize the power loss.
GPS sells belts, so it's fine for them. On a light bike or kart, 30-40% power loss is not very noticeable, if you
don't know better.

The solution is to make a proper jackshaft, have the driven mounted opposite of it's current state,
and have the driver inboard, unlike it's current state.

 

[Denny]

So my way of telling him he has a bad set up is not the right way to do it? It was my mistake I did not look good enough to see it was a 40. And I am sorry! But if he did the research like I suggested it would have not been a problem.
Everything you told him he would have learned and much more. Teach a man to fish and he can eat for a life time. Give him a fish he eats for a day then begs for more. The simple fact is we are both wrong, they are both on backwards from their original design.

 

[karl]

Look good at again. It sure looks like a 30 to me!

Sure, Its a 40. Look at the nut on the driven. Cut and dry. Sorry.

Also the backplate looks nothing like a 30 series backplate, if you had experience with this stuff.

 

[karl]

The simple fact is we are both wrong

No , that is what I explained. You are wrong.

Everything you told him he would have learned and much more. Teach a man to fish and he can eat for a life time. Give him a fish he eats for a day then begs for more.

Inspirational, A for effort.

They are both on backwards from their original design.

Yes, due to the limitation of the backplate, as I explained.

Nothing against you denny.

 

[karl]

You might really want to go to gokart supply website and do some research..

https://www.gokartsupply.com/4044seri.htm

 

[MaidenInk]

He already has a 40 series, this is not good advise. Could cause someone to waste a couple hundred bucks.
Not trying to be rude, but it is quite easy to tell a 40 series from a 30, if you are familiar with this stuff.


Nope, bad advise again. The driven clutch has the red spring, not yellow. Its on the "right" way.



The backplate 40 series is inherently flawed , sorry you bought someone else's mistake.

That's why GPS won't sell it on ebay, they can't control the feedback, same with the juggernaut clutch.

The 40 series was designed to run with the driven opposite of yours, hence why its driver is "backwards"

If the driven if mounted outboard, like yours, it needs to float on a proper jackshaft the width of the belt, with
the yellow reverse wound spring. But the backplate setup does not allow this, that is why it is flawed.

The "fix" is to flip the driven, like your setup, but is not how the clutch is supposed to work.

Hence it's a "get what it is" situation.

Many are in denial and cannot admit their cart/ drag bike could possibly be flawed,
and after spending GPS money on their clutch setup, have too much pride to be capable of accepting this.

So just be aware, some will say "its just fine" but burn multiple belts a year and don't realize the power loss.
GPS sells belts, so it's fine for them. On a light bike or kart, 30-40% power loss is not very noticeable, if you
don't know better.

The solution is to make a proper jackshaft, have the driven mounted opposite of it's current state,
and have the driver inboard, unlike it's current state.

Thank you Karl, this is what I was looking for. All I kept coming up with is places want to sell me their set up. I did not find any info that said 40 series backplates don't work. I have absolutely no problem taking it off throwing it in the trash and starting from scratch, I expected to put some work in. The cart was next to nothing and has a brand new electric start predator 420 on it, I figured it was worth picking up. I fully expected to put time and money into it and I am ok with that. I just needed someone to point me in a direction, so thank you very much!

 

[MaidenInk]

https://www.gokartsupply.com/4044seri.htm

Should I start with something like these?

Search Results for: jackshaft kit

www.gokartsupply.com

 

[karl]

Your welcome, those kits are just fine.

Or just pillow blocks and keyed shafting is durable, but less attractive .

The 40 series driven comes in 3/4 and 5/8. If yours is a 3/4 unit,
I would reccomend pillow blocks as the 1 and 3/8 x 3/4 bearings are not great.

Whats the gearing and tire size?

 

[MaidenInk]

Your welcome, those kits are just fine.

Or just pillow blocks and keyed shafting is durable, but less attractive .

The 40 series driven comes in 3/4 and 5/8. If yours is a 3/4 unit,
I would reccomend pillow blocks as the 1 and 3/8 x 3/4 bearings are not great.

Whats the gearing and tire size?

If I remember correctly the little gear is 10 and it looks like the big fella is 60, the rear tire size is 23x10x10. Also I should probably clarify the intention......off road fun. Trails and such. Also looks like the one that is one there is 5/8. Thank you

 

[madprofessor]

Others here will have a better guess than myself, but I'm guessing that with those extra tall tires the current 6:1 ratio needs to be reduced down via the jackshaft sprockets to nearly twice that ratio. Thinking 10:1 minimum, could even go 12:1 if you don't need a lot of top end speed.
When selecting jackshaft sprockets, remember that pillow block bearings (I've got 8 of them on my current kart) are pretty much all rated at only 4K rpms, although they'll take more.
Example: My CVT output sprocket is 12-tooth on a motor that should spin up over 7K rpms. Went from the 12-tooth CVT to a matched pair of 24-tooth on jackshaft. Since they match, it keeps my final axle ratio of 6:1 unchanged, but now 7K rpms of the motor is only 3.5K rpms of jackshaft's pillow block bearings.
You could do something like the 24 on your primary drive, and only 15 on the secondary, just an example. Regardless of choice, the jackshaft's where you do your ratio change.

 

[Denny]

Your ratio should be a good starting point for now. You may have to lower it some though.

 

[ThunderKart79]

I promise you the red spring is inboard ad the yellow is outboard at least for comet and the back plates are the easiest way to install these clutches with your driven clutch on backwards you cannot create any preload it is kind of like installing a turbo 400 and putting just enough fluid to mess the Tranny up you know it does not work the way it is so try flipping both of the clutches around if you need an extra kick go to go power sports and watch there video and they will walk you through the way the manufacturer drained the system to work and I will bet $500 that yellow spring is outboard and red is inboard to get the red to work the outboard you have to bend the snot out off the spring to make it work the bet is for the way comet designed it to work

 

[LSDOG]

Others here will have a better guess than myself, but I'm guessing that with those extra tall tires the current 6:1 ratio needs to be reduced down via the jackshaft sprockets to nearly twice that ratio. Thinking 10:1 minimum, could even go 12:1 if you don't need a lot of top end speed.
When selecting jackshaft sprockets, remember that pillow block bearings (I've got 8 of them on my current kart) are pretty much all rated at only 4K rpms, although they'll take more.
Example: My CVT output sprocket is 12-tooth on a motor that should spin up over 7K rpms. Went from the 12-tooth CVT to a matched pair of 24-tooth on jackshaft. Since they match, it keeps my final axle ratio of 6:1 unchanged, but now 7K rpms of the motor is only 3.5K rpms of jackshaft's pillow block bearings.
You could do something like the 24 on your primary drive, and only 15 on the secondary, just an example. Regardless of choice, the jackshaft's where you do your ratio change.

This probably don't do anything, you have the max acceleration a = g * fraction
If the ratio is too high the wheels will struggle because they have too much power that pass that power to the ground can handle

 

[Millwright]

Re: series 40 install, I have seen many YouTube videos on this, all of them, including one from go power sports, show the driven pulley with the spring positioned outboard. Can all of these experienced " builders" be wrong?
I'm am in my first build attempt, and have set up torque ( 40 ) the same way. As it is, turning the driven pulley around will require a fair amount of redesign and rework. I am thinking of purposely putting the belt out of alignment in the idle position, so that it reaches alignment when under throttle. Still not perfect, but I think it would help on belt life.
Also, I have a 13 tooth drive sprocket and a 48 tooth driven sprocket with 16.5" wheels. Any opinions on this. I'm more interested in top end speed, put of course need a little get up and go!