Chain and sprocket hate eachother

[imclix]

For longer than I would like to say, I've been trying to resolve the issue of my chain not correctly seating on my sprocket, causing a loud bang.

Chain is DID 525 Heavy Duty
Front and rear sprockets are 14t 525
All test runs are up a small incline, I do 10-20 meters at low throttle and then about 80% throttle.
Engine, sprockets are from a DL650 Suzuki Vstrom.

In no particular order, here's a list of everything I have done prior to these videos to fix this:
Replaced chain
Adjusted chain tension from very loose to street bike spec
Cut off and re-welded sprocket as it wasn't perfectly straight
Installed a Panhard rod so the sprockets are always aligned
Aligned the sprockets to within 0.5mm
Added a third bearing to axle to eliminate any flex
Moved control arm mounts to pivot inline with jackshaft to remove any change in tension over suspension travel

The only thing that I can think of to fix it is to cut off the sprocket and put a new one on as there is a small chip in one of the teeth from when the chain has snapped on. The chip seems far to small to cause this issue but right now I'm out of ideas.

Video #1
- Spring loaded tensioner, was fairly well lined up but under load may have been a few mm out.
- Chain can be seen not seating perfectly throughout the video but mainly at 36sec
https://www.youtube.com/watch?v=amjK_QH9M7I

Video #2
- Chain guide and no spring tensioner but a bit more overall tension than video 1.
- Chain doesn't seat until high load
https://www.youtube.com/watch?v=hnTOOGOiNHg

Video #3
- Tried to align the guide better but the kart kept stalling. This ended up happening.
https://www.youtube.com/watch?v=7-ieE0CCqKM


Thanks for reading, any advice would be greatly appreciated.

 

[GreyW00lf]

Whats your Overall gearing like as we're only seeing the axle spocket... and that looks to be on the small size, unless you have something on the other end that we're not seeing.

 

[Marius]

sizing up the axle sproket might help

 

[imclix]

Whats your Overall gearing like as we're only seeing the axle spocket... and that looks to be on the small size, unless you have something on the other end that we're not seeing.

Thanks for the reply.

I've got 15t off the engine to 40 something tooth on the jack shaft. Then 14t from the jackshaft to 14t at the axle.

 

[GreyW00lf]

Thanks for the reply.

I've got 15t off the engine to 40 something tooth on the jack shaft. Then 14t from the jackshaft to 14t at the axle.

Could we either get a short video or some pictures please, of the whole setup starting from engine to jackshaft. Something just doesn't seem right and without seeing it i can only guess.

Edit: 15 to 40 is too low you need 6:1 gear ratio meaning for example, 10 tooth on engine, 60 on jackshaft.

 

[imclix]

sizing up the axle sproket might help

Thanks for the reply.

Yeah I've thought that a few times but I have seen at least one or two builds with relatively small sprockets (maybe a bit more than 14t) work perfectly fine.

Thinking about it now, it does seem like the most likely culprit.

 

[GreyW00lf]

Thanks for the reply.

Yeah I've thought that a few times but I have seen at least one or two builds with relatively small sprockets (maybe a bit more than 14t) work perfectly fine.

Thinking about it now, it does seem like the most likely culprit.

plus what size tires do you have as well as it will effect the speed too as it's likely changing the final gearing.

 

[imclix]

Could we either get a short video or some pictures please, of the whole setup starting from engine to jackshaft. Something just doesn't seem right and without seeing it i can only guess.

Edit: 15 to 40 is too low you need 6:1 gear ratio meaning for example, 10 tooth on engine, 60 on jackshaft.

Sorry I only mentioned this in my build thread, forgot to say it here. The engine is straight out of a Suzuki vstrom road bike and I have kept the stock gearing. So that adds 2:1 of the primary reduction and 2.5:1 of 1st gear

Also having smaller tyres than the motorbike's has shortened the gearing more.

 

[GreyW00lf]

hmm, i think i'll have to bow out and let another answer your questions from here on out as my knowledge is a bit limited at this time.

 

[imclix]

hmm, i think i'll have to bow out and let another answer your questions from here on out as my knowledge is a bit limited at this time.

Your help is greatly appreciated, I hadn't even considered that gearing could effect it in any scenario.

 

[GreyW00lf]

your very welcome, if i come across any info that might help you i'll send it your way.

 

[MattWll]

I solved this problem by welding the tension roller.

 

[imclix]

I solved this problem by welding the tension roller.

I don't quite follow what you mean by this. Could you please elaborate?

 

[mckutzy]

Lets see some pics of the whole machine and rear end, not so close up.... I think I see something that needs a whole picture...

 

[imclix]

Lets see some pics of the whole machine and rear end, not so close up.... I think I see something that needs a whole picture...

Thanks for the reply,

I've added some pics and there are some more on my build thread.

If there's any other photos that could be helpful I can take some more.

 

[anickode]

I think your axle is bending under heavy acceleration.

Try adding a center bearing? Axle flex puts extra slack in your chain and throws off the sprocket alignment.

 

[imclix]

I think your axle is bending under heavy acceleration.

Try adding a center bearing? Axle flex puts extra slack in your chain and throws off the sprocket alignment.

Thanks for the reply.

Originally I just had a bearing near each wheel and I ended up bending the axle. I've since straightened it and added in a center bearing.
You can see it in the video just next to the sprocket.

I might try to take a video from a different angle to see how much its still bending and possibly add in another bearing on the other side of the sprocket.

 

[anickode]

Thanks for the reply.

Originally I just had a bearing near each wheel and I ended up bending the axle. I've since straightened it and added in a center bearing.
You can see it in the video just next to the sprocket.

I might try to take a video from a different angle to see how much its still bending and possibly add in another bearing on the other side of the sprocket.

It could be tweaking the entire crossmember assembly a bit too. I do see the center bearing now... Maybe that square tube isn't stiff enough to brace it sufficiently?

 

[imclix]

It could be tweaking the entire crossmember assembly a bit too. I do see the center bearing now... Maybe that square tube isn't stiff enough to brace it sufficiently?

I have noticed a fair amount of extra slack under load. You're definitely right. I will add some bracing in this weekend.

I hate to get my hopes up but this seems like it could be the fix.

Thanks heaps mate

 

[mckutzy]

As I understand this... The chain is coming off under acceleration and under recoil...

I see one issue...
Is the center of pivot of the rear end, the sprocket in the middle?? Or not..

It looks like the recoil is loosening the chain...