Incremental Chain Tensioning, Chain Management

MotorbikeMike

Dealer
Dec 29, 2007
477
1
18
Sacramento
HI well, I thought sure that I had written this here, but in case not, here goes.

Other than a true spring-loaded guide, which some I knew in the past had made, the best tension roller LIFTING the chain is NONE.

This is how it came to be that I invented the aluminum T-Shirt.

Remember that when you move the engine forward the chain slack reduction is twice the distance of the movement of the engine. One full link-set is one inch, therefore the MAX that you would ever need to move your engine would be 1/2 inch. Additionally, good is good enuf, and there is no need for perfect, which, actually does not exist.

Now, take your rear sliding motor mount, make a pattern on a piece of extruded aluminum strap, not to exceed the width of the mount or it can hang up in the chain.

Originally I drilled the holes, and slid them on the studs in-between the rear motor mount and the engine case. AFTER pulling the engine in and out several times it occurred to me that when I aligned the front-end on my 55 Chevy, that the shims had a tab-handle, and did not require removing the bolts, just loosen, pry open, slip in and re tighten.

This is where we are now, your shims look like t-shirts, and the "arms" of the t-shirt lay on top of the 2 studs, with the body of the shirt hanging down, full-length to space the engine evenly, and rock-solid.

Next installment, after you-all ask anything you like about this, I'll explain the other section of Chain Management, which we invented (Kevin "evil elvis" Waddle, and Meself), the Upstop Roller.


Mike
 

Pablo

Master Bike Builder & Forum Sponsor
Dec 28, 2007
3,665
6
38
Duvall, WA PNW
www.sickbikeparts.com
Good stuff. I really don't have, or at least don't think I have, room to "move the engine". But 1/2"? Maybe! Please post pictures (I'm a visual guy).

I am indeed interested in the next installment.

My chain is really the weakest link on my bike. When will the silly thing stop stretching?? (I'm serious - anyone know?) I take two links out, then two more, then two more and this is all after it was pretty tight to start with. This is driving me crazy!!

I took a long ride on Saturday and sure enough the chain stretched so much it wouldn't stay on. Maybe two more links!!:-||
 

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
11,843
237
63
up north now
300 miles....that's what I got to before the chain was done stretching.

Look for bending/fractures of the frame if the chain just won't tighten.
 

MotorbikeMike

Dealer
Dec 29, 2007
477
1
18
Sacramento
Hi, well, ok step two in the conquering of the "chain slappin' blues". After I once started building these bikes, I began to use KMC HD cruiser bike chain instead of whatever was in the kits.

Sadly, on about my 8th or 10th engine SpitFire had changed to the bigger, dumber, heavier chains. I revolted, and returned to the Bicycle Chain. These can be overcome with KMC's BMX chain, tho the pitch is a wee bit different.

Here a dremel, with a diamond bit is your best friend, work out all the burrs, sharp edges, reshape the teeth as needed, AND you should run the chain thru, over and over, refineing your teeth's shape, till the chain does not try to "climb" the sprocket, once this is done we can proceed to improve the rest of the system.

Also know, that the "shoulder" of the sprocket sometimes needs some relieving, AND that your master link too many times does not have the DOGBONE shape, and you either need to relieve that shoulder, or "dogbone" that master link. Taking care of this will stop many unexplained chain derailing, snapping, or blowing the master link episodes, and maybe long walks home?

I NEVER use the kit chain, they must be made of some metal version of silly putty.

Sooo, replace your chain, adjust it with the T-shirts, (With your carb as LEVEL as possible).

AFTER you replace your chains, we will get on with step 3 of the "Chain Slappin Blues".

Are ya with me?

Mike
 

bravofire84

New Member
Feb 13, 2008
46
0
0
ok this is my first time building a bike kit and my chain is to long i think i might go with a "aluminum t-shirt" show pic if u can.
 

deacon

minor bike philosopher
Jan 15, 2008
8,117
3
0
north carolina
thanks joe,

Of course now the darn chain is running like a dream. I have no idea what I did except it is as tight as a banjo drum. I didn't leave any slack at all in it. I know that's not right but it runs better now than it ever has. Of course it will probably pop tomorrow now that I have said so much about it.
 

deacon

minor bike philosopher
Jan 15, 2008
8,117
3
0
north carolina
Usually bravofire,

It is a few links too long. You can either use a chain break or take the master link loose and figure out about how many links you need to remove and carry it to the bike shop. Either way you need to save what you remove, odds are you will reconfigure it someday. That's why I'm begging chain now. I don't know where I "SAVED" mine.
 

MotorbikeMike

Dealer
Dec 29, 2007
477
1
18
Sacramento
Step 2:

IF you cannot get your single-speed chain the right lenght to work on your bike at the same point as your engine, have you considered that the drive sprocket on a coaster brake comes in (I think) 17, 18, 19 29, 22, and 24 teeth?

Adjust accordingly, Next I'll try to find a pic of my "Upstop Roller"

Mike
 

NunyaBidness

Active Member
Jun 29, 2008
1,062
1
38
memphis tn
yea I just used some nuts that were a little bigger than the studs, I put them in the same place your shims are at. works great and no chain tensioner to bugger things up
 

Rogwillsie

New Member
Oct 28, 2008
30
0
0
Seattle, WA
Thanks to all of you, especially you Mike, I am on the way to resolving my chain problem. I'll probably use the nuts idea to move my motor back and tighten the chain. I worked on it today and had trouble making it work because the bolts are too short. I moved them out of the block to have more thread, then stripped the thread on one bolt trying to get the nut tight. Oh well, will have to scare up some new bolts, longer ones and make sure they are secure in the block. I hope a hardware can furnish what I need. Didn't know this would be such a project and I have trouble thinking of anything else while the issue is unresolved. I will also get a new chain, as suggested by Mike.
 
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mralaska

New Member
Aug 16, 2008
42
0
0
Deerfield, NH
Rogwillsie - I was unable to find anything in the hardware store. My choices were to either buy american sizes and a tap, or to order metric. One threaded rod was enough to hacksaw into enough studs for the entire engine:
http://www.mcmaster.com/nav/enter.asp?partnum=99055A120
In retrospect, I might have been better off buying zinc coated because the steel rusted up the first time I rode in the pounding rain:
http://www.mcmaster.com/nav/enter.asp?partnum=99067A245
Some might be inclined to go with stainless but I do not think stainless would be appropriate for this application.

Regarding comments about chain stretch; I am using the stock chain. I have several hundred miles on it now and it immediately quit "stretching" as soon as I got rid of the tensioner. I think much of the "stretch" I thought I had initially was actually the tensioner wearing or giving. Having the smaller engine is, no doubt, easier on the chain but I still ask it to pull my 240lb bulk up the side of a mountain every time I take it out so I am not giving it any breaks.

What kind of intake manifold do you have?? Does such a short one make any difference??
The intake is stock. I have attached a picture of the engine taken from a more normal angle.
 

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