My minibike is an unknown frame as I got it off facebook marketplace but im having a problem with the chain, its a straight chain and it falls off on a few occasions which isnt the issue, what is the issue is that the frame and the wheel are too close so when it falls off, the chain gets eaten up by the sprocket bolts. It keeps on breaking and I was wondering if there are any gaurds or anything for the sprocket to stop it from destroying the chain. Thanks!
Chain falls off and breaks. Help!
- Thread starter Lawdawg
- Start date
Do you have any photos of the back wheel/rim area and also the chain alignment? Might give some on lookers more option ideas to offer you. I understand what your saying and whats happening, sounds like a chain alignment issue is in play either under load or at high rpm causing the whole malfunction.
Sorry for the late response! Although I appreciate your very quick response. Here are the photos, the alignment seems to be alright but I think the chain might be bent slightly from the last time it fell off and broke as it hasnt always been bent. you can see the low clearance between the frame and sprocket. Any ideas on what I could do to solve the issue?
I might be crazy but the chain appears to be from a bicycle maybe? The numbers on it indicate that possibility. The links struck me as being longer than usual at first glance then of course i researched the numbers. I would look and try see what pitch that clutch and sprocket might be, my guess would be #35.
The clutch at least is #41 I previously bought a #35 and had to return it because it didn't fit either one. but maybe I get a new sprocket perhaps? The chain I bought is a basic powersports-type roller chain or at least was advertised as such. the chain has only fallen off when I’ve ridden over sticks and things like that which I’m pretty sure is just due to it being a straight chain but I’m mainly concerned about the fact that it breaks after it falls off. Is there anything that could prevent that like maybe a guard or something?
Im kind of thinking like Triley41395. What ever you have the most of alike (2/3rds) it sounds find the same for the rear sprocket. Match all your driveline groups pitches. Then you might find the chain throwing to cease. However if you want to tinker with extra chain security in a failure, try see if your sprockets thickness, once found, will allow using a countersink bit on your mounting holes and then use countersunk screws. That would flush out the clearance between wheels sprocket and frame causing minimal damage to the chain in a failure. Otherwise you would have to mount a halo ring to the sprocket to catch the chain and getting that concentric and welded or screwed on would be a task. I think you will find matching your drive group components to go a looooOng way in helping you out. Hope some of all this helps you also. Good luck with your build.
Ok, you got a 10 tooth clutch sprocket (china clutch) and a #41 chain. Next time you buy chain buy the #420 chain . Take the washer off the front that you have on the crankshaft. You want the clutch to be able to FLOAT on the crankshaft. Rear sprockets NEVER runs true and since there is more chain wrapped around the rear sprocket it dictates where the clutch will be on the crankshaft so just let it float. YOU never want to fix the clutch to the crankshaft with set screws that is why it says on the donut of a Max-Torque not to use them but use a bolt and washer. But who ever reads instruction, certainly no man ever does. You put some spacer washers on the crank and that is part of your problem. If the clutch is the same length then get some flat washers 11/16 OD with a 5/16 ID and thickness is normally .060 , put these under your flat washer on the end of the crank. These are to extend the crankshaft length so you get some float.
Normal crankshafts on American engines are 2.297" long, a Max-Torque clutch is 2.220 in length which tells you there is .070 float built into the clutch. This float is to give some play to help in alignment. Another thing to do when you cannot get the clutch to move in further towards the engine is take the snap ring off and pop off the drum and sprocket and take the sleeve of the clutch to a belt sander and take off all the material down to the inside edge of the snap ring. Since you are holding the clutch on with a bolt and washer so you really don't need the snap ring. The now 2 piece clutch has no where to go and you have just gained almost .100 in float. De3finitely will help in getting good alignment when you are fighting for an 1/8".
We do this in racing situation like on a 120 snowmobile where the clutch is inboard mounted and your gearing is correct but you want to get more slip so you can just pull out the shoe assembly without having to break a set up and put in a different shoe assembly with either a higher engagement or lower engagement depending on what you need. With six different springs and two different shoe styles in the "SS" clutch you can dial it in to what you need for engagement. You can mix shoe styles as long as you do it evenly--light /heavy, light/heavy, light/heavy.
This site is for education and that is all I try and do.
Normal crankshafts on American engines are 2.297" long, a Max-Torque clutch is 2.220 in length which tells you there is .070 float built into the clutch. This float is to give some play to help in alignment. Another thing to do when you cannot get the clutch to move in further towards the engine is take the snap ring off and pop off the drum and sprocket and take the sleeve of the clutch to a belt sander and take off all the material down to the inside edge of the snap ring. Since you are holding the clutch on with a bolt and washer so you really don't need the snap ring. The now 2 piece clutch has no where to go and you have just gained almost .100 in float. De3finitely will help in getting good alignment when you are fighting for an 1/8".
We do this in racing situation like on a 120 snowmobile where the clutch is inboard mounted and your gearing is correct but you want to get more slip so you can just pull out the shoe assembly without having to break a set up and put in a different shoe assembly with either a higher engagement or lower engagement depending on what you need. With six different springs and two different shoe styles in the "SS" clutch you can dial it in to what you need for engagement. You can mix shoe styles as long as you do it evenly--light /heavy, light/heavy, light/heavy.
This site is for education and that is all I try and do.
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I think your problem is the alignment. You cant see it accurately with the chain on but its pretty easy to see by eye with no chain especially with your huge sprocket. Im guessing your motor mount is bent or just moving around under load. That looks like a pretty weak setup. With such a big sprocket is very susceptible to throwing the chain when the axle becomes unparallel with the crankshaft because the top of the sprocket will be pointing at one side and the bottom will be pointing at the other. A 420 or better yet a #40 chain will definately help keep it on. But do a better job of the alignment first and if you have a welder add some bracing under the engine plate will help alot