new to motorized bike building

Jeffrey

New Member
Jul 23, 2017
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Hi all, brand new to this game.Just put together my first bike( An old Murray beach cruiser single speed with coaster brake) and im having some issues. when i measured the chain and broke it, the chain was pretty tight.In fact it was too tight to install the tensioner. So i left it off, thinking eventually the chain would stretch. well, i tooled around the block on it and when i pulled into garage, the chain was very loose, so loose that it comes off the rear sprocket. Now the engine didnt move, and the rear wheel didnt move. Can anyone tell me how this happened? Everything seems to be tight and in the same position it was when i first installed the chain. At first i was thinking maybe the rear sprocket was off center. But it doesnt get tight then loose as the the wheel rotates, its just loose. Any help in telling me where i should be looking would be greatly appreciated. Also if anyone has a pic of how the bikeberry upgraded chain tensioner is supposed to be installed, that would help too. Thank you
 
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mike carter 2

Member
Nov 23, 2011
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west virgina
being too tight might have caused too much pressure on the bushings in the chain,causing friction,causing heat .....stretched chain.did you lube the chain?
 

Jeffrey

New Member
Jul 23, 2017
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Yes,I lubed chain very well with high quality chain lube. How much free play is chain supposed to have? When it was tight it had about 1/2" of deflection. I wouldn't think that would be tight enough to overheat chain. But what do I know.
 

Chaz

Well-Known Member
Jun 3, 2012
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Vancouver, British Columbia
KC is right, it's time to install the tensioner. I did a quick google image search and there's a vast array of tensioners and install methods. If you search "motorized bicycle spring loaded chain tensioner" you will see how to install. I'm guessing what you have is this?

Whatever you do, don't go by bikeberry's install video because they install it upside down... good grief.
 
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KCvale

Well-Known Member
Feb 28, 2010
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Phoenix,AZ
KC is right, it's time to install the tensioner.
The only thing a spring loaded tensioner does is try to make up for a rear sprocket that is not true.

The stock tensioner does NOT need to be installed the way it comes out of box, you can put the wheel on the other side of the long mount.
 

Jeffrey

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Jul 23, 2017
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Yes Chaz, that's exactly what I have. I have it installed. It bounces a little, like rear sprocket is not exactly dead on. Then the spring came off once. I'm thinking of maybe getting a better quality, heavier spring than berry gave me. Do you think I should remove rear sprocket and try to get it perfect? The way this bike is made, I don't know if I can get it much better. I really appreciate your help guys.
 

Chaz

Well-Known Member
Jun 3, 2012
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The spring tensioner can bounce a bit even if the sprocket is perfect. The rear sprocket does need to be pretty much dead on with no wiggle or up and down. It's hard to judge how it is when you are riding the bike. It's easier to see if you can get the back wheel off the ground and move the pedals with your hands. That is probably what you are doing but I mention it just in case. I think it's better to get it centered and then go around adjusting the bolts for any wobble issues.

No harm in trying a stronger spring.

you are welcome, lots of good fellows here who are willing to help.
 

Jeffrey

New Member
Jul 23, 2017
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Yes, got wheel off the ground and tried to eye ball the sprocket, tightened a few of the bolts..I mean it's close, but without a dial indicator I can't know if it's dead on. One other thing, I'm getting a little chain pop when I roll it backwards(engine off, clutch disengaged) forward seems to be pretty smooth. Any thoughts on that?
 

Chaz

Well-Known Member
Jun 3, 2012
1,004
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Vancouver, British Columbia
I think if you can eyeball it to about 1/16 inch variance then you are good enough but keep an eye on it in case the sprocket settles a bit over time. Ideally you should be barely able to see it move if at all.

The reverse pop might be from touching a fender or brushing the tire. It could also be just wearing in. When you have the chain under load it wears in that position, but when you roll backwards it could be still a bit stiff in that direction. That should clear up over time. Make sure your master link is oriented to point (closed end) towards the engine on the upper section of chain.
 

Burros90

New Member
Aug 17, 2017
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Hello guys, my son 15 years old bought the silver horse kit in Amazon, also bought a huffy beach bike to install it, since the mountain bike trek he has there is not enough space to mount the engine.
We put it together ran for a few miles, the front studs broke almost flush with the block, remove them and reinstall new ones of SS seems they are holding now since them.
Then after that the chain broke, first time installing it, we used 2 small pieces of rubber 1/8" thick between the two side of the tensioner and the bike frame to avoid direct vibration metal to metal, after install new chain the tensioner keeps sliding or actually rotating towards the rear wheel, making the chain to rub agains the tire and the chain to move out of the tensioner, popping the chain out of the rear sprocket and tensioner wheel, I think that maybe the reason for the chain to break on us. We did removed the rubber to generate better grip, however the tensioner still rotating towards the wheel making the same effect than before when the chain broke, wold you be so kind to shed some light here?
I saw a chain tensioner with a spring a a black wheel may help, what's your opinion? suggestions?
thanks in advance for any help.
 

crassius

Well-Known Member
Sep 30, 2012
4,032
155
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USA
when chain stay is a bit thin to hold the tensioner, I cut an inch or so of old handlebar, split it into "C" sections and use them as shims to hold the tensioner

when chain is adjusted right, there are NO tight spots to pull the tensioner down
 

allen standley

Well-Known Member
Oct 22, 2011
1,115
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Bangor, Maine
Yes Chaz, that's exactly what I have. I have it installed. It bounces a little, like rear sprocket is not exactly dead on. Then the spring came off once. I'm thinking of maybe getting a better quality, heavier spring than berry gave me. Do you think I should remove rear sprocket and try to get it perfect? The way this bike is made, I don't know if I can get it much better. I really appreciate your help guys.
Hello Jeff and Welcome!
For you and others, If you cannot afford the aftermarket 3 bolt Adapters and sprocket specific to them, you may want to consider this affordable upgrade to the Kit supplied Sprocket and Rag Joint. This mount actually grabs the hub and insures a true mount without the Rag only bobble set up supplied with the kits. Best part is you can use the sprocket you already have.It is used in conjunction with the rag joint. So far I've used 3 of em easy peasy no issues.
https://www.amazon.com/Sprocket-Ada...=8-1&keywords=motorized+bike+sprocket+adapter
 

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Feb 2, 2017
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California
Guys.... if you have beach cruisers with fenders, either take them off the bike or reinforce them before they break apart and kill you! Search up on this site before it's too late.
 

allen standley

Well-Known Member
Oct 22, 2011
1,115
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Bangor, Maine
Good point Potato about the Safe fenders. Thread is about tensioners. I try to avoid using them. I'll go so far as half links on motor side, Pedal side or both. I've also had good luck by changing pedal side wheel sprocket from smaller to bigger. I have shortened and lengthened Rear engine mounts. Experimented alot. There is no magic formula. To achieve happy chains is a time consuming quest and sometimes a fruitless effort. My advice- avoid the stay mounted tensioners and look at the engine case mounted ones.
Tips for happy chains go here
https://motorbicycling.com/media/albums/happy-chains.1499/
Tips for safe fenders go here
https://motorbicycling.com/media/albums/safe-fenders.1277/
Notice the chain tensioner on that White bike. Those are custom Built by a member of this forum
Turbobuick, the wheels are custom cut by another member Mapbike.
Good luck to ya and be patient.
 

KCvale

Well-Known Member
Feb 28, 2010
3,967
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Phoenix,AZ
Guys.... if you have beach cruisers with fenders, either take them off the bike or reinforce them before they break apart and kill you!
If your build vibrates so bad you are shaking the fenders off, I think it best you look into your engine mounting problem and not scare people away from having fenders.

~85% of my builds have fenders and no problems.

If you start with a good bike you check it of course, maybe reinforce an 'L' bracket for the front, but that's it.

Just count your mount points.
The more you have, the better.
This Micargi build has 5 fender mount points front the rear.



That of course was a bad example because electric bikes have no vibration at all, a fender isn't going to hurt you without giving you ample warning either.
 
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