Rear Sprocket Jumping Under Chain

[JaggerWolf]

Today out of the blue I started hearing a really rough rumbling noise when taking off in our Manco Ez Rider kart. I got out and gave it gas and noticed that the rear sprocket would spin under the chain, causing the chain to ride over the teeth.

The chain was old so we went and bought a new chain....threw it on aligned everything, gave it the appropriate slack and tried it again....same issue.

Took apart the rear driven unit and checked the spring - put it all together like I have done a few times - Everything looked good. Started it up....same issue.

I tried moving the engine back and forth to try different tension - still no fix.

I am at a lose and have tried everything I can think of - The only thing that even helped a tiny bit was to ratchet the engine a bit to the right (see pic) But even then it still slips when starting out - once its up to speed it's fine...but then the minute you have to slow down and speed back up it does it again. I will try to make a small video of it in case that helps.

Any ideas??

 

[JaggerWolf]

Here is a quick video - If you watch close at the beginning you will see the chain rise up as the sprocket spins under. This is a brand new chain, and brand new sprocket with the correct tension on the chain.

https://www.youtube.com/watch?v=75g46thMsLw&feature=youtu.be

 

[OzFab]

I could be wrong but, it appears the sprockets are not aligned; also, is it just the camera or is the back plate vibrating?

 

[JaggerWolf]

The vibration was the camera - It definitely doesn't vibrate like that

After some more investigation I took the engine completely off the kart.....found out it had a cracked support bar under the engine, that was allowing the whole motor to tweak whenever it got some torque....which would in turn cause the sprocket to go out of alignment. I welded it all up and threw it back together and so far the issue seems fixed.

 

[OzFab]

Yep, that'll do it...

Congrats on investigating & finding the issue

 

[BirdFanatic]

have you tried pushing the engine forward or back ? to tighten chain and using lock washers

 

[OzFab]

Cam, read post #4; he already solved the problem...