Any Creative ideas for this problem?

[Allthingswithamotor]

Hey folks!

Any help will be appreciated!

I have a loose chain from my motor to the jack shaft (please see pic) and I am having trouble making a spring loaded chain tensioner for it.

The other picture shows (with red minibike) how I would like to make it however i am not sure If it is possible as my chain is outboard of the frame rather than like with this red mini bike where the chain is inside of the frame.

Has anyone got any ideas of how I could make it? Ideally I would like the spring to be as short as possible (to avoid it wobbling too much) however I do not have much to attach it to.

Thanks!!

 

[Ebrownie]

It it too short to put in a half link? A half link would help it a lot if you could fit it in. If not, then you would want the tensioner on whichever side does not have the load on it. However, I see an issue where if you have the tensioner push in, it may hit the other side of the chain since both of your sprockets are so small.

 

[mckutzy]

First start by shortening the chain by a link or so... Then make the same but reverse.
Attach the spring to the motor. There is a threaded boss near the exhaust to put a bolt(I think it's metric).

 

[Ebrownie]

I don't know how this would work, but you could try putting an idler sprocket between the two sides and just having it sit there, fixed. It would spread them apart and tension it, but you would have to get the right sized sprocket. I think this should work because theoretically both sides go at the same speed.

 

[mckutzy]

In this application a ghost tensioner won't work well... On a bicycle yes...

 

[ML-TOYS]

Dont you have slots in your motor plate ? Shorten chain, half link if need be and push motor forward.
DONE !

 

[big-d]

I agree^^^^^^^

If you need, want, an option to add a spring tensioner though. This is how I would do it. The pink circle is the roller, the blue lines are the arm and pivot shaft, and the green line is the arm on the opposite side that the spring attaches to. It could (would) be at a different angle then the arm with the roller. That way you could have room for a spring to pull down on the arm. This would also put it on the slack side of your chain.

You could use a piece of tubing for the pivot shaft and flat strap for the arms. That way you could use a through bolt for it to pivot off of with simple tabs on the frame.

 

[Allthingswithamotor]

Thank you very much for the helpful replies!! I did not know that you had to put the chain tensioner on the side with no load. This will make it more awkward as the no lode side is on the bottom but I can see that it makes sense!
Unfortunately I do not have slots for my motor plate. However I could add a half link! big-d where would the spring go? As doesn't the tension have to be downwards?
Thanks again!

 

[big-d]

The spring would go from the bottom frame rail on the right side of the bike up to the green arm. That is the only purpose of the green arm in the drawing. (there is a faint yellow line representing the spring in my drawing)

I think You would be better off shortening your chain and adding slots to your motor plate in the long run though. That way you would just slide the engine forward to tighten he chain.