Chain Jamming

GoldenMotor.com

Soapdish

New Member
Mar 20, 2012
10
0
0
Carbondale, CO
So I've had quite a few problems with my newly acquired bike (which I love), and they've taught me a thing or two about general engine mechanics, which i greatly appreciate.

My most recent problem is that my chain keeps getting jammed up in something, stopping it from turning and completely locking the bike up. It threw me over the handlebars yesterday, and I'm scared to ride it until I can fix it. And I'm not sure what to do. A friend suggested that my chain is too loose, and to take a link out. Any suggestions and/or instructions?

(I took off part of the chain housing for reference)

 

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
11,837
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up north now
Remove a link, make sure you oil the chain too. They usually jam up inside the case. If you look closely, you will likely see fresh metal in there by the sprocket.
 

Al.Fisherman

New Member
Sep 9, 2009
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Calera, Alabama
Remove a link, make sure you oil the chain too. They usually jam up inside the case. If you look closely, you will likely see fresh metal in there by the sprocket.
Few more things that WILL help. The chains that come in these kits are really junk, sometimes the links don't rotate on the bushing. This can most of the time corrected by removing the chain and lub and work each link. Bevel each gear tooth on the rear sprocket (just enough to take the sharp edges off), as some teeth can get caught in the chain a lock it up. Proper alignment of both sprockets and tensioner. About 1/2" play in the chain. And a better chain is available. at places like Tractor Supply, among others. Now all thing said I've been running on the factory chain since 3/2009. I have done all of above, but have a new chain on hand should I have problems with mine.
 
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Bicycle Motor Fun

New Member
Sep 17, 2011
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Warren, Michigan
SoapDish; In looking at your posted photo, I would say one thing that your chain is awfully loose! It appears that you could take out at least one link(set). Like the posters ahead of me wrote, chain alignment is very critical as well. Make those changes, and take 'er out for a nice slow check ride. BMF
 

Len455

New Member
Mar 11, 2012
144
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Phoenix az
Get a new chain. Try a #41 chain, just slightly smaller. Or like said above just take out a link, well you actualy have to take out 2 but you know. Other option is to get a half link and not use your tensioner but people say thats dangerous, but what do they know lol.
Good luck
zpt
 

Motorized Bike Guy

New Member
Jan 4, 2012
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Vermont
One issue I had with mine was when I got it. I had it on correctly and it would still jam up and so I looked very closely and I saw that a link was twisted, so i had to carefully twist it back with plyers, now it works great.
 

axe

New Member
Mar 9, 2011
9
0
0
Michigan
This thread has me terrified lol,

Is this something that can "just happen" one day, like riding full speed, if the chain locks, you wont go over the handlebars right? just skid to a halt? Im new to riding, so I am still working on getting comfortable lol.
 

KCvale

Well-Known Member
Feb 28, 2010
3,966
57
48
Phoenix,AZ
This thread has me terrified lol,

Is this something that can "just happen" one day, like riding full speed, if the chain locks, you wont go over the handlebars right? just skid to a halt? Im new to riding, so I am still working on getting comfortable lol.
Well, if your ride looks like a death trap it probably is safety wise.

If your kits rear sprocket is so poorly made it isn't even flat and you have to file crap off of each of the 42 teeth then that should tell you something too.

The original poster of this topic hasn't been back but it is one of those topics people ask about so...

I would guestimate that 90% of all rookie builders chain problems are caused by simply not doing a good job installing the rag joint sprocket on the rear wheel or just flat having crap to start with.

If your sprocket does not spin true and free of both vertical and horizontal wobble you will ALWAYS have problems.
On top of that it has to be in near perfect side to side Horizontal alignment from the motor to the wheel.
Far too many rookies think they can 'bend chain' around a tire with a tensioner (just lowers and shakes head), you can't.

One last thing is the tensioner itself...
I prefer not to use one if I can, but at least if you do, mount it far enough forward on the chainstay so that if it comes loose it leans in to the rim and not the spokes.

A back wheel lockup won't sent you over the handlebars like say a broomstick handle thrust through your front wheel while riding literally bucking you off will, it will stop you rather abruptly from behind.

The bottom line here is even a stock 48cc is a high power drive train and it darn sure better be in perfect solid alignment if you don't want it to fail.
 

2door

Moderator
Staff member
Sep 15, 2008
16,302
175
63
Littleton, Colorado
Read the above post, save it and print it then paste it to your workbench.

Roller chains need to be aligned and tensioned correctly. They aren't made of rubber, they don't bend around corners and they will only perform as designed when they are straight, aligned, tensioned and lubricated properly.

The drive chain/sprocket alignment and concentricity not being correct is without a doubt one of the major causes of problems with a chain drive system on a motorized bicycle. Done right, they are trouble free and will give you miles of pleasurable riding. Done wrong and you won't go a block without problems.
Tom
 

rustycase

Gutter Rider
May 26, 2011
2,746
5
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Left coast
Bye golly, What They Said !

I'm a real hack, far too casual about many things, but I'd be a real bad person to write on a global forum that someone should do anything foolish.

Even the tiny 48cc ht chinagirl kits have the capability of taking almost any pedal bicycle to it's design limits.

Safety should be a primary concern.

Stopping quickly becomes more important than gaining speed!

The china products we are playing with here are suspect, to say the least.

Any component could give up the ghost at any point in time, so do your best to see that all the others are in the best condition you can keep them in.

These are the same folks who killed off a bunch of our kittycats with melamine plastic laced food meant for them, included sulphur compounds in residential sheetrock, and build boatloads of plastic toys for children with known toxic ingredients in them.

They are fun, they are cheap, but DO exercise appropriate caution!

:-||
rc
 

KCvale

Well-Known Member
Feb 28, 2010
3,966
57
48
Phoenix,AZ
Read the above post, save it and print it then paste it to your workbench.
Thanks Tom, and wouldn't it be nice if the poor excuse for an Instruction Manual in the kits did too? ;-}
I try to pound that same message home every time I see one of these chain topics here.

Other than a solid motor mount THE most important part of these builds is the chain drive, and you simply can't fudge either and expect it to work under load for long.

I have 2 simple drive tests I always do.

1.
I hold the bicycle top bar with one hand, then try to rock the motor back and forth as hard as I can with the other hand.
If it moves at all it fails, period.

If I can wiggle it with my 50+ year old arm strength then even a bone stock 48cc is going to lean left and throw off the chain alignment.

2. I put the rear wheel in a front fork (upside down bike) and give it a spin.
If the wheel isn't even true it has to be made true because if the whole wheel wobbles any sprocket mounted to it will too.

I am lucky enough to have a close fellow bike builder friend that helps me double team installing these rag joint sprockets to a wheel in 20 minutes or so... we have it down to a science actually heheheh ;-}

It sucks having to do one on your own, I know, but with help you can breeze through the several steps of checking and tightening everything for a good solid and true sprocket mount.

Once you have your sprocket mounted you can easily judge how much vertical up and down wobble it has from the sprocket not being centered on the hub (every other step of checking as you tighten), and also see the side to side horizontal wobble if the rag joint bolts are not all torqued down correctly.

There is almost always a bit of wobble even with direct hub mounted sprockets one way or the other, and a little (1/16") is acceptable, it is the big wobbles that will screw you up, especially if you have more than one or two.

"My chain gets tight, then it gets loose when I roll it..."
Well, the sprocket isn't centered (vertical wobble) ;-}

One thing you should ALWAYS do BEFORE you mount the rag sprocket is check the the level of the rag sprocket itself on a true flat hard surface, lay it cupped side with the teeth down, bowl side up, and see if it rocks in any direction.

If you can make it wobble on a table it's going to horizontal wobble the chain no matter how you adjust the rag joint bolts, it's a bent gear!

Again, for me 1/16th" is acceptable, and I have had luck putting an 1/8th", maybe even a 1/4" wobble sprocket on a concrete floor with a chunk of wood on top and giving it a couple of blows with my 4 pound short handle sledge hammer to true it up, if it is much more than that you better make sure every other aliment is perfect is all the more I can suggest.

Well, that and when you roll it around looking for final alignment you oil the chain at the rag sprocket as you go ;-}
 

Soapdish

New Member
Mar 20, 2012
10
0
0
Carbondale, CO
Remove a link, make sure you oil the chain too. They usually jam up inside the case. If you look closely, you will likely see fresh metal in there by the sprocket.
Bikeguy Joe, I sincerely apologize for not replying, I've been getting sidetracked with many more issues ive had with this piece of work. I tightened the chain by raising up the pulley wheel, and to be honest, the thing ran like a dream for 3 days. Then, the inevitable breakdown happened. Previously I re-bolted the motor to the frame, but the back mount only had 1 of the 2 screws in it. I thought it'd be fine. Well, the vibrations were so bad that my intake manifold snapped right off the f*cking motor. So now I've got to order new parts and wait a week probably for them to get here. And seeing as I don't have a car, this is gonna be ****.

 

killercanuck

New Member
Dec 17, 2009
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Wallaceburg ON
Great advice by all. That sucks Soap... you could always remove the drive chain altogether so it'll ride like a bicycle until your intake comes. :)

gl, don't wear out the shipping tracking number :p
 

2door

Moderator
Staff member
Sep 15, 2008
16,302
175
63
Littleton, Colorado
I hope your replacement manifold is steel and not the cast aluminum one that came with earlier kits. They had a bad reputation for breaking like yours did.
When you get the new one make sure the gasket mounting surface is flush. Run it over a sheet of sandpaper backed up with a sheet of glass or another surface which you know to be flat. You'll quickly see that it needs some work. The flatter that surface, the better the gasket will seal.
Good luck, keep us posted on your repairs.

Tom
 

rustycase

Gutter Rider
May 26, 2011
2,746
5
0
Left coast
Ouch!

That hurts when your only transportation dies.

Gosh, if you notice some sort of vibration, it's best to investigate before it does damage... vibration is an indicator of a problem coming on, and something always breaks!

Sry to see you are having a run of bad luck.

Good luck!
rc