Binding, popping or whatever you call it.

[Sauer_35]

I picked up a Yerf Dog 3203 for the kids. I tested it before I bought it and had no issues. It has a new Predator 212 and the floating torque converter setup. I only took off once and ran it around the block never coming to a complete stop. When I got home and started riding it, I noticed a binding feeling and heard pop. Upon inspection I noticed the sprockets were out of alignment, easy fix. But the binding popping is still happening. I notice when it does it the swing arm torques up and releases. Not sure that is the actual cause, but I can see the shocks compress some when this happens. below are some pictures. I have videos but haven't figure out how to upload if I even can.

 

[Denny]

That belt may not be the right one. The numbers don’t look familiar. GoKart Supply has a great write up about servicing the cvt and measuring for the proper belt. Use only a Genuine Comet belt. Cheap belts don’t last and cause other problems.

 

[Sauer_35]

I was thinking that maybe a possibility but haven’t had the time to inspect it this afternoon. That will be an easy fix and I hope it is it.

 

[Sauer_35]

Just checked it, it’s the right shape, asymmetrical with the flat side to the motor. Doesn’t t appear too loose.

 

[Sauer_35]

12-8487 is the same as the Comet 203589A. The driven pulley is 6” and the center line distance is 6.75”. So according to that this is the correct belt.

 

[Denny]

Maybe they just need taken apart and serviced? The site I told you about above has great instructions.

 

[madprofessor]

Chain and sprockets alignment looks good, teeth are sharp, guessing you've got good chain tension when parked also. That only leaves flex and/or twist in my mind. Like under load, the motor mounting plate (which is kind of long) flexing down towards the axle a smidgin bit, which loosens the chain tension when you can't be watching it very well. Then the chain skips teeth, but has proper tension again when you stop. You need to know for sure if the popping is from the chain, or from the belt binding in the driven.

 

[Sauer_35]

I’ll check it out today. I can tell you the the swing arm flex’s up. The very back end of the kart, behind the axle flexes up off the ground.

 

[ezcome-ezgo]

Image 7 on the far side of the axle there is a fair amount of daylight between chain and sprocket. You sure they are the same gauge?

 

[Sauer_35]

Pretty sure both at 41, it’s the stock sprocket. But it won’t hurt to confirm

 

[Sauer_35]

Pulled the drive to clean it and just a general check. This washer was stuck behind the clutch pack.

 

[Sauer_35]

Pulled the drive to clean it and just a general check. This washer was stuck behind the clutch pack. View attachment 135068

Well this was not the issue. So far I’ve clean the driver, removed a loose washer from the inside, confirmed the chain is aligned and loose enough but not too loose. The chain measures to be a #40, i don’t think changing to a #41 will make a big difference since they are so close in size. But the issue is still there.

 

[panchothedog]

You used the term floating torque converter set up. I am not sure what you mean by that. The plate part of the torque converter should be bolted to the side cover of the engine and torqued to about 20 lbs. No movement at all. The belt really has no way to pop. They are supposed to be lose at idle,and sometimes squeal if they are slipping. It sounds more like a frame issue of some sort. But even that, if rear subframe picks up, the motor and rear axle should be moving in unison, thus not affecting chain tension. Can you get someone to follow behind you and try to watch what is happening.

 

[Denny]

I wonder if the secondary is binding in some way? It’s tough trying to diagnose these things since we are not there in person. You did use only graphite powder or liquid to lube the primary correct? I just don’t know. You are sure the sprocket is correct behind the driven also?

 

[Sauer_35]

I wonder if the secondary is binding in some way? It’s tough trying to diagnose these things since we are not there in person. You did use only graphite powder or liquid to lube the primary correct? I just don’t know. You are sure the sprocket is correct behind the driven also?

I used graphite. As far as I can tell, I haven't pulled it off, it is the correct size and said to be the original

You used the term floating torque converter set up. I am not sure what you mean by that. The plate part of the torque converter should be bolted to the side cover of the engine and torqued to about 20 lbs. No movement at all. The belt really has no way to pop. They are supposed to be lose at idle,and sometimes squeal if they are slipping. It sounds more like a frame issue of some sort. But even that, if rear subframe picks up, the motor and rear axle should be moving in unison, thus not affecting chain tension. Can you get someone to follow behind you and try to watch what is happening.

You are correct, I had never heard the term "floating" until I bought this cart, and it may not be the correct term. I was told that they meant floating because it's attached to the frame. But it's all tight. I have a video where I followed behind and you can see what is happening. I'm going to try to get it uploaded to YouTube and post the link on here. And I think it's something to do with the frame too.
.

 

[Sauer_35]

Here is a quick video I threw together.

Yerf Dog 3203 swing arm/drive train binding and popping.

Enjoy the videos and music you love, upload original content, and share it all with friends, family, and the world on YouTube.

youtube.com

 

[madprofessor]

It's like I said about the motor mounting plate...............While your swingarm does jump up/down a little while the chain is skipping teeth, it's still like Pancho said about the engine and swingarm moving in unison, that ain't it.
In the rear shots of the acceleration, you can see plain as day the motor mounting plate flexing up/down like a flag flapping in the wind. That's loosening the chain as torque pulls down on the flexible mounting plate, then the chain skips teeth, giving the plate a moment to flex back up, then the process repeats. A few times per second.
Momentum of the 40 lb. motor jouncing up/down is jerking on the swingarm, making it have the up/down motion as a secondary effect of the motor already in motion. (1): Plate flexes down, taking motor with it. (2): Chain skips, releasing tension on chain. (3): Plate and motor flexes back up, retightening the chain. (4): Sudden stop of motor upward motion (chain retightening) yanks up on the swingarm, making it hop up/down a little also. Lather, rinse, repeat.
When it happened to me on my 17" long by about 6" wide plate, I spliced on (2 pieces because of chain proximity) underneath on the chain side some 1/2" angle iron, welded every couple of inches. Not good enough to stop the flexing. Eventually had to wedge in crossways a removeable piece of 1" angle iron that basically shortened the mounting plate's flexing portion to about 10" instead of 17".
That fixed it. Now the 15+ hp. motor no longer flexes the plate, so the tooth-skipping of the chain is cured completely.

 

[Sauer_35]

It's like I said about the motor mounting plate...............While your swingarm does jump up/down a little while the chain is skipping teeth, it's still like Pancho said about the engine and swingarm moving in unison, that ain't it.
In the rear shots of the acceleration, you can see plain as day the motor mounting plate flexing up/down like a flag flapping in the wind. That's loosening the chain as torque pulls down on the flexible mounting plate, then the chain skips teeth, giving the plate a moment to flex back up, then the process repeats. A few times per second.
Momentum of the 40 lb. motor jouncing up/down is jerking on the swingarm, making it have the up/down motion as a secondary effect of the motor already in motion. (1): Plate flexes down, taking motor with it. (2): Chain skips, releasing tension on chain. (3): Plate and motor flexes back up, retightening the chain. (4): Sudden stop of motor upward motion (chain retightening) yanks up on the swingarm, making it hop up/down a little also. Lather, rinse, repeat.
When it happened to me on my 17" long by about 6" wide plate, I spliced on (2 pieces because of chain proximity) underneath on the chain side some 1/2" angle iron, welded every couple of inches. Not good enough to stop the flexing. Eventually had to wedge in crossways a removeable piece of 1" angle iron that basically shortened the mounting plate's flexing portion to about 10" instead of 17".
That fixed it. Now the 15+ hp. motor no longer flexes the plate, so the tooth-skipping of the chain is cured completely.

So, if I'm following, I could just go back to this setup and resolve the issues.

 

[madprofessor]

Is that a new motor mounting plate with a jackshaft? Whatever the motor is mounted on, it absolutely must be as rigid as anywhere else on the frame is. I'd guess almost anything could improve things over the rubber bands it's mounted on now.

 

[Sauer_35]

To be on the same page this is the stock swing arm, the black plate is the original jack shaft plate that mounts between the motor and swing arm. It has 6 bolt holes. And the aluminum plate is what is currently attached to the side of the motor and has not frame mounting location.