Chains 410 vs 415 drive chain, catasrophic failure brand new engine

bike issues solved

ok first thing's first, all bolts and nuts on the back sprocket need to be changed, chinese metal is very weak same as the ones in the chain tensioner go to your local hardware store match up the bolts and buy 10.9 higher the number stronger the bolt. get yourself a good chain tensioner the stock one with out the spring is useless. then change the gas line to rubber fuel line (canadian tire). after that change all rings those ones they give (red) that go on the carb toss them and get better ones they leak. last but not least chinese 415 chain is weak so if you can find a better chain thats the key im trying out kmc 415h right now on amazon to see if that will make a difference if not back to the original.

i hope this thread helps! ive been doing trial and error and for the abuse i put mine threw i find these things will save you a whole lot of headache. oh and go to walmart for 5.99 you can get a whole pack of bike cables universal. you will eventually need them. and a chain breaker wouldn't hurt, i got a heavy duty one at princess auto for 15.00 walmart canadian tire ones that say made in taiwan are junk!

reember when getting this bike heavy duty all the way. trust me you will be happy. and be safe these things can go fast enough to kill ya. get a full face helmet. (motocross)

anything else questions or something i don't know you can email me will.canada19855@gmail.com
 
I just had my first chain failure. I have less 12 miles on it. One of the links split in half on one side.

I'm assuming the chain that came in my kit was a cheap, junk chain from China. And I want to put one on there that I'll never have to worry about. Provided I don't have any clearance issues with the #41 chain, is there any reason not to run it?
 
I just had my first chain failure. I have less 12 miles on it. One of the links split in half on one side.

I'm assuming the chain that came in my kit was a cheap, junk chain from China. And I want to put one on there that I'll never have to worry about. Provided I don't have any clearance issues with the #41 chain, is there any reason not to run it?

I have a Kip chain tensioner and there are clearance issues with the #41 chain so I use 415 from manic mechanic which also fits my custom sprocket and hub assembly perfectly. No more squashing my spokes. A little pricey but well worth it.
 
Pics of the breakage:

20130819_131544_zpsdbb2c58e.jpg


20130819_131619_zpscbe93b75.jpg



Judging from the wear on my chain and sprocket, a slightly wider chain would serve me well. Being that I know I have the clearance, I'll throw a #41 on it and see how it does.
 
I've only seen chain failures in two situations, no matter how cheap the chain, it will work fine if installed properly. The two things that tear up a chain are engine coming loose or frame bending/cracking/breaking. Your pics show that your chain was rubbing on something at the outside of the links and the twisted look implies a bad alignment (most likely at the rear sprocket).

Hard to tell from just a pic, but maybe your tensioner fails to feed chain perfectly straight onto rear sprocket.
 
Pics of the breakage:

20130819_131544_zpsdbb2c58e.jpg


20130819_131619_zpscbe93b75.jpg



Judging from the wear on my chain and sprocket, a slightly wider chain would serve me well. Being that I know I have the clearance, I'll throw a #41 on it and see how it does.

I've never had the motor side chain break but I've snapped two on the pedal side. It looks like that chain is dry as a bone. Do you have any lube on it at all?
 
I've only seen chain failures in two situations, no matter how cheap the chain, it will work fine if installed properly. The two things that tear up a chain are engine coming loose or frame bending/cracking/breaking. Your pics show that your chain was rubbing on something at the outside of the links and the twisted look implies a bad alignment (most likely at the rear sprocket).

Hard to tell from just a pic, but maybe your tensioner fails to feed chain perfectly straight onto rear sprocket.
The two sprockets are aligned well. And the twisted look is probably because the spring-loaded tensioner is still putting tension on it with one broken side.

When I originally built this bike, I opted against a tensioner and shimmed the lower mount to get the proper chain tension. I found that within short periods of use, the engine would roll left along the lower mount centerline. The front mount would limit movement to some extent, but it rolled enough to give enough chain slack that it would jump teeth. So, I added a sprung tensioner and all has been wel until now. I wonder if this slight roll could have caused the chain to fail? if so, I'll have to fab something up to prevent it from rolling...

20130801_231254-1mod_zps40430453.jpg
 
I've never had the motor side chain break but I've snapped two on the pedal side. It looks like that chain is dry as a bone. Do you have any lube on it at all?
Honestly, it is dry. I've had the bike out twice since I built it, and I forgot to ever lube it. I'll be sure to lube it's replacement.
 
Looks like the chain may have hit something. There are scape marks just to the right of the broken link. Look for something that may be in the route of the chain that my have done this or you my have curbed it. Never seen a chai n do that unless under a really heavy load and these bikes don't produce that much load.
 
Even the cheapest bicycle chain will have greater tensile strength than the torque of a motorized bicycle engine can overcome.

Looking at your photo, the chain side plate has failed at the largest sectional thickness which leads me to believe that the chain did not fail from exceeding maximum tensile loading.
The failure looks like impact damage, which is most likely caused from a sprocket tooth striking the side plate or a foreign object being wedged in between the sprocket and the chain.

My motorized bicycle has covered over 50,000 kilometers (31,000 miles) and i have never had a chain fail (9 speed, 8 speed, or 415) from exceeding the rated tensile strength, even at 100% stretch
I have however had a failure caused by chain to sprocket misalignment, resulting in the side plate being punched in half.
 
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