Probably an easy problem for the pros

[cwicher10]

I bought a motorized bicycle from a guy on ebay, and sadly I wish I would have gotten a kit and done it myself in order to better learn about all the functioning parts. The bicycle was shipped with the motor mounted and everything besides a couple wires and other basic parts to throw on. (Chain was on as well)

After I got the bike assembled, I took it out for it's first start up outside. I played with the choke, primed, and went down a hill for the start. As soon as I let off the clutch, the motor turned over and then then chain almost immediately jammed on the sprocket (assumption) and I came skidding to a halt. A simple backwards roll released the chain. I tried a couple more times and got the same results.

I walked the bike back into the garage and played around with the tensioner a little bit. I made it a tad bit more snug thinking that it had too much play and was getting jammed because of it. I took it back out and got the same results. This ****ed me off and I threw it in the garage and haven't touched it until the other day.

I love the concept of a motorized bicycle and want to invigorate my motivation to make it work. Since I gave up on my initial attempt, I've managed to misplace the tensioner that came with it, and I'm not sure of where to get another one that's compatible. All that's left of it is the bracket that it bolts onto near the chain to push it up.

I'm at a crossroads, because I want to look for another tensioner to order so that I can troubleshoot more with the bike, but I never figured out why the bike was jamming and skidding to a stop on every start up attempt. I'm not a "bike guy" at all and I'm new to all this, so any information that will help me sort this out and enjoy this concept would be amazing. I realize I'm probably leaving out much needed information, so just ask away and I'll do my best to comply.

Thank you ahead of time for the help.

-Chris-

 

[Hammond Egger]

Don't despair, you can order a new tensioner from about any of the vendors on here. Try Bikeberry or pirate cycles. Can you take pics and post them? It sounds like the sprocket is seriously out of alignment.

 

[chainmaker]

Welcome to the forum..youll get it figured out with a little help and soon enough youll be off and motoring!!

 

[rohmell]

Try these things:

Ride down the hill without releasing the clutch. The engine drive gear and rear sprocket will spin and if you make it down the hill, then nothing is jamming.

You should be able to ride around while holding in the clutch. If this is the case then the drive gear, chain and rear sprocket are OK, since they all turn anyway, whether the engine is running or not.

Let us know the results of this test, and then we can go to some more troubleshooting steps.

 

[2door]

8 days after the original post:

I really don't understand it when a guy comes here, asks a question, get's replys then doesn't come back to say thank you or at least tell us what he found. I'm sorry, newbie or not, I think that's being inconsiderate.
Tom

 

[rohmell]

Some people just give up too easily, then its off to Craigslist to dump the thing onto someone else.

 

[Schwinn the Fox]

Well, does anyone have a way to fix this? I have the same problem. When I hold in the clutch it freerolls just fine, but when I release it. The chain gets jammed up into the clutch arm housing almost rightaway. Sometimes I can roll it backwards and retry, but most of the time when It jams up, I need to take the clutch arm cover off and pry the chain out of its bunched up position. It never jumps off the sprockets though, just bunches up. Im fed up to with this thing >.< anyone know a good way to actually fix it? And yes I have a chain tensioner on my bike, a good one.

 

[baadboy]

The chain gets jammed up into the clutch arm housing almost rightaway. Sometimes I can roll it backwards and retry, but most of the time when It jams up, I need to take the clutch arm cover off and pry the chain out of its bunched up position..

sounds like the chain is to long or there is to much slack in the chain

 

[Schwinn the Fox]

Thats what I thought, So I took off the chain and shortend it one link, but then it was too short, so I had to make it its original length.

 

[baadboy]

try to adjust ur idler pulley to take out as much slack as u can

 

[Schwinn the Fox]

If your not talking about the chain tensioner, then I dont know where to find the idler pully, I didnt thing these engines had one; or maybe I dont know what Im looking at.

 

[baadboy]

lol yes that what im saying

 

[Schwinn the Fox]

lol ok, Ill tell what I did in detail with pictures ^^.

This is my bike.

You guys already know the problems, now heres what I did about it.

I adjusted the chain tensioner a few times to reduce some slack, and that still didnt work. as you can see this tensioner was custom made to prevent chainslap, and it works quite nicely... when the bike does.

This is the tensioner without compression.

This is the tensioner with compression.

As you can see, it works quite nicely with chainslap. Anyway, the tensioner works and keeps the chain nice and stiff (The bottom chain). The top chain will be all tence, then so loose the top of the chain almost hits the bottom. So I tried shortening it, and it was to short, so I put it back together... Man this stinks... the chain is not bent and everything rolls fine with the clutch in... I dont get it. Below is a picture of where the chain gets stuck whenever I let out the clutch.

Now you guys know what everything looks like and what I did about it.

 

[baadboy]

well bro im out of ideas some one here mite have a better idea on this one all my builds ive did i use a stock idler pulley with a screw thro the frame to hole it in place

 

[Schwinn the Fox]

Its pretty much the same thing, But mine moves with the chain, not that big of a difference... I was thinking maby the chain rides up the teeth in the engine sproket? Maybe but i dont know...

 

[camlifter]

you have a spring tensioner on there, those need a positive stop to work right. with out it the top run of the chain gets slack in it and lets the chain catch inside the front sprocket cover. get rid of the spring tensioner or make a stop for it.

 

[baadboy]

thats what i was just thinking about

 

[rohmell]

You wrote that the top chain is tense, then so loose that it almost hits the bottom. This happens when you turn the wheel? If so, then to me, this means that the rear sprocket is not centered.

 

[Schwinn the Fox]

Its centered, theres no wobbel at all when I ride (when I did ride) lol and what to you meen positive stop?

 

[camlifter]

when you bump start the bike it's being driven by the rear sprocket at that point. the rear sprocket is pulling on the bottom chain run to turn the engine sprocket. the spring tensioner is being pulled to it's max, the bottom chain run gets tight, the top chain run goes slack and the chain bunches up in the engine sprocket cover and jams, in time it will break the engine case. thats why the stock tensioner doesn't have a spring.
push your bike with the clutch in, then pop the clutch and watch what the chain does. wou'll see what i mean.
a spring tensioner needs a bolt or something to limit how much it will move so you don't get to much slack in the top run of the chain while starting.