Interesting findings...or not.

[Bikeguy Joe]

Just got my latest kit today.

The first thing that caught my attention was the sprocket.

First, gone are the elongated holes...does this mean I'll get it centered the first time?

Second, the teeth are more blunt and wider than the other sprockets I have, in fact a one speed bike chain fits the older sprocket, but not the new one.

Old one with regular bike chain-

New one with regular bike chain-

Comparison of teeth, new sprocket in forground, old one behind it-

The kit chain fits both, but looser on the old stlye sprocket.

Comments?

 

[deacon]

My only kit has the flat sprocket on which the chain looks like it fits the same at your new one. My holes were perfectly round. Tell me will a bike chain fit the front sprocket. The one in the motor because it looks to me like a crank sprocket could be made to work on the rear.

 

[Norman]

You might get lucky on the new sprocket. I have not been sent a sprocket with the slotted holes I have seen them on ebay kits etc. I'm glad I have not had to try the slotted sprocket. It might of ended up in low earth orbit. I was sent a bmx chain that will fit the sprockets made for the 415 chain but I have no idea that the chains size is that chain doesn't want to fit the front sprocket very well so I've not used it. Bob and I were looking at a way to poor boy a smaller rear sprocket and we fount that the front sprocket on some multi speed bikes(mountian bike I think) have a 38 tooth sprocket and the 415 chain will fit fine now we need to make a sprocket adapter to try out the idea. The adpter should not be hard to make and if we find the right front sprocket all we will need to do is get the center hole the right size to match up to one of the 415 rear sprockets we have laying around then match drill the mounting holes and away we go cheap smaller rear sprocket.
Norman

 

[nogoodnic]

Well I'll be darned. I have not run into this issue and have only used single speed chain in a pinch. One thing that I do on my builds is to take a dremmel to both front and back sprockets. This results in a much smoother chain run...Kelly

 

[Autocycler]

Hey All,

Does dremelling the sprockets help quiet down the clatter much? I'd welcome any tips on quieting the clatter down. My wife's bike has a very quiet stock exhaust, which leaves the drive chatter for all to hear.

 

[Norman]

You tried a good chain oil the kind that won't sling off? I don't know of a brand , the bike shops could point you in the right direction. There used to be a type made for motocross bikes that worked good and didn't sling off. Now I don't know if it will quiet the chain down that much but it might.It was in a spray can.
Norman

 

[Autocycler]

Hi Norman,

Yes, I'm using a name brand motorcycle chain lube from the local Honda dealership...Bel-Ray I think is the brand and it does "stick" much better than regular bike chain lube (which rained lube in every direction). It makes sense that better lubrication will quieten things down some.

It looks like my chain is riding low on the front sprocket so that the chain hits the lip below the cogs. I think this might be a source of the clatter. Would a slightly narrower chain solve this issue? I'm running a 415 chain right now.

 

[Norman]

I would have to lie to answer that as I don't know. If the chain hangs on the teeth then the thing might make more noise than it should. I don't hear as well as I used to so what you are hearing I might not. Sorry I don't have a better answer.
Norman

 

[deacon]

Is it hanging down or hitting on the sides. If it's on the sides a narrower chain might help if there was one. if it's hanging down and sagging onto the lower part of the opening it might be the slack or angle of the engine as related to the sprocket. Those are just guesses. Mine makes a lot of different noises I have about given up trying to figure them out.

I think my rear sprocket isn't quite centered as well.

 

[nogoodnic]

Hey All,

Does dremelling the sprockets help quiet down the clatter much? I'd welcome any tips on quieting the clatter down. My wife's bike has a very quiet stock exhaust, which leaves the drive chatter for all to hear.

I would say yes. On my bikes it has made everything smoother and I don't notice nearly as mych chain slap...Kelly

 

[Autocycler]

Thanks for sharing your wisdom on this. Mine makes a symphony of noises too, Deacon. It's kinda hard to pin down where it is coming from.

Now I just realized I installed an 70cc carby on her 48 motor which explains why it seems to run so lean. So, I'll swap the carbs and deremel the sprockets. Sounds like a perfect wintery Saturday afternoon!

 

[Bikeguy Joe]

I thought my chain was noisy, but after I "soundproofed" the bike, it was much quieter.

I used an adhesive backed foam weatherstripping on the back side of the chain guard and under the fenders. I also sprayed some of that "Great Stuff" foam in the tubes of the frame.

My off center sprockets made the chain quite noisy too.

Too tight on the drive chain will make it noisy as well.

 

[paul]

thats a great idea about spraying foam in the motor bicycles tubes. gonna have to do that

 

[Bikeguy Joe]

Just be very careful not to get it in the bearings where the pedal crank goes....don't ask me how I know.

Best if done with the bike apart, you can use tape to seal the areas where you don't want foam. Remove the tape when the foam has cured.

Dont forget to do the handlebars and seat post as well.

I also forgot, silicone caulking (cheaper to buy it in a caulking gun tube than to buy it in the little toothpaste type tube) can be used to deaden sound in the same manner, apply liberally to any sheet metal.

 

[billy02]

I thought my chain was noisy, but after I "soundproofed" the bike, it was much quieter.

I used an adhesive backed foam weatherstripping on the back side of the chain guard and under the fenders. I also sprayed some of that "Great Stuff" foam in the tubes of the frame.

My off center sprockets made the chain quite noisy too.

Too tight on the drive chain will make it noisy as well.

I'm just doing my second build of a 50cc Starfire & after 4 or 5 tries the rear sprocket is almost, but not quite, centered. Will anything get damaged if I use it that way? Billy02

 

[BarelyAWake]

Well - while there's no gettin' it perfect sadly, but ya gotta be really picky 'cause even a lil offset will cause excessive vibration, spoke damage, and can even lead to motor mount failure

Get a sprocket adapter ifn ya can - the stock sprocket mount is by far the biggest problem w/these things.

 

[Bikeguy Joe]

I ran one bike with the sprocket waaaay off for 750 or so miles. While it did make a ton of noise, it never caused me any other problems.

Take your time, and get it as straight as possible....it can be done.

One tip is tighten it down most of the way, then use a heavy rubber mallet to do the "fine tuning", then finish tightening.

 

[billy02]

I thank you guys for the responses, however varied. I've got it centered within 1/32 which should be fine. I had used the method Joe suggested, tapping with a rubber hammer & re-tightening, but, the sprocket wouldn't change position. I think that once you tighten it the spokes make indentations in the pads that you're pretty much stuck with! I thought of turning the pads over but I was afraid that a second set of indentations would be too much for those pads. Also, when I first tightened the bolts I went around snugging every other bolt until they were all tight. I believe that was a mistake that gave me some wobble in the other direction that is more troublesome than a little bit off center!! Too late it hit me that a 9 bolt pattern has 3 equilateral triangles that should make a perfect tightening pattern. I think that the most important thing I learned was to get the sprocket where you want it before you tighten it all the way!!! I'd like to hear any more thoughts y'all have on the subject.

 

[2door]

Billy,
That's what Joe meant when he suggested using a hammer to get it right. Don't tighten the bolts completely until you have 'tapped' the sprocket into position. 1/32" is close but not perfect. Believe me, it can be done with some work, some patients and understanding of the mechanics involved. I've had better luck with a metal hammer and a block of wood than a rubber hammer. The impact is more solid. Off center is bad but a wobble can cause just as much trouble. Some kit supplied sprockets have a built-in wobble that needs to be addressed and some are actually drilled off center. If you have one of those puppies then you have two choices; replace it or make it work. I've streightened warped sprockets with large crescent wrench and/or a block of wood and a hammer. If the center hole is drilled off-center you can either mill out the hole to a larger size and center the sprocket by the teeth (outside diameter) instead of the hub. Good luck, keep us posted.
Tom

 

[billy02]

Well, surprise surprise, I was mistaken. I went back & loosened all 9 bolts til I could center the sproket by hand. Then I began tightening the bolts a little at a time using the 3 triangle method I spoke of earlier. Along the way, 2 of those cheapa.. bolts stripped & were replaced. Anyway, I kept checking the centering & this time it was staying on center. I have a small work table with a hole in the center large enough to accomodate the smallest 2 gears of the 7 speed sprocket. The wheel will then spin freely resting on the 5th gear sprocket. This is where I check & adjust for wobble. This time it came out perty durn good.