Bike is nearly perfect NOW....

This works, made mine a bit differant and gotta do it again as LoneWolf described.

But for the swivel action, instead I used flat washer type needle roller bearings. Not cheap but worth the extra smoothness of the swivel action.
The needle roller bearings come in 3 parts.
1a. the actual needle roller in flat cage. Measure the same size as the bolt to fit through.
1b. The hardened bearing metal washers ( 2) that go on either side of the needle roller bearings.

2. Molly Grease
3. "End Float Nut" so you tighten the swivel bar just enough so there is no slack in the bearing, then a lock nut and do it up tight on 2 nuts type of thing, leaving the bearing tensioned just right; firm but no slack.

And you need that bolt to stop the swivel from going too far down.

It's awsome, a "springy" feel when slowing, all that tension being taken up by the spring. Taking off is another "planet", smooooth.

Post my version pics soon when it's all finished.
 
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Well I finaly got one to work for now.
It does take a bit of beating about, there are angles to think about, not too much spring tightness and not too much loosnes either.

One of the problems encountered is when releasing the clutch, the swivel arm can tend to go down too far, lonewolf has added a bolt to stop this.

I suggest a 2nd spring, just lose enough to not be active during normal riding, but cuts in when releasing the clutch. ( double action spring chain tensioner)

I did not use the drill hole method, but used the kit's adjustment slot, but has a lock washer to grip.

The swivel bolt swivels on a flat needle roller bearing set. By "set" it means it comes in 3 pieces, 2 are flat washer like bearing metal that is a must, to work with the needle rollers. This gives the swivel 0 tolerance therefore no side play.
Lots of molly and it works fine. Tighten it up with lock washer on inside, so the lock washer is between the bearing washer and kits tensioner arm.

Stage 2 pictures will show another version I'm working on the next build, but I must admit, the one shown here;
fenderhole: you can also buy one from livefastmotors
http://cgi.ebay.com/ebaymotors/Motor...spagenameZWDVW
its the same one i used on my bike, works excellent! but i guess that takes all the fun out of making it yourself.
is a good alternative also, but have not tried it yet.

On early test, when releasing the clutch and as soon as the engine starts, the chain may lock up up against the casing and the small sprocket.
Idler wheel may have to be implemented at the small sprocket end to stop the chain from jumping to high.

This is a viable project for anyone to try.
Well worth the effort, smoother riding and no metalic jolting which may cause stress on bike's frame and engine mounts.
or buying a ready made spring tensioner is a cool option to.

Available tools used for now; drill press, angle grinder, bench grinder.
 

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The best chain tensioner is no chain tensioner.....

Here is a pic of one of my customers bikes.

Much quieter and smoother with none of the idlers churning.

To do this you need to use a quality chain that won't "stretch"
and the strongest chain is a KMC K910 as used in the pic

Standard 1/2" pitch with only 3/16" between the plates and sexy
cut off side plates!

I don't understand you guy's that keep pushing 41 chain. It has 1/4"
between the plates
, skinny sideplates and isn't as strong.

On the Chinese two strokes front sprocket the 41 chain can move so far
to the right ( engine side) that it rubs the case
 

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Forbisher, the chain in the pic is KMC 910.
It's half a link too long, if I remove 1 link it is too short.
The supplier say's they cannot supply half a link, nor can they supply a spare master link if the original is lost or damaged.

For the record; a place that does chains, they wanted AU$100.00 labour plus cost of chain to make one fit right.
About AU$160.00 - AU$180.00 in total.
 
Forbisher, the chain in the pic is KMC 910.
It's half a link too long, if I remove 1 link it is too short.
.
You solve the chain tension problem by moving the motor up or down in the frame.

Cut the back mounting block down
make a custom back mounting block
or use spacers
 
You solve the chain tension problem by moving the motor up or down in the frame.

Not on this particular bike, previous owner's builder had already crucified it by driling a hole in the front down tube.
Also, the standard chain tensioner is too short in adjustment, meaning if you place the kit's tensioner in line with the rim, the wheel don't reach.
The tools available are minimal, no milling machines, lathes, all that sort of stuff to make custom as required
There was some milling done, the C-Clamp had to be milled to fit the seat down tube, cost: $20.00 and had to wait 2 weeks and 3 days.

Having a go at making spring tensioner is what this thread is about.
 
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Running the chain with no tensioner works. When you put the rear sprocket on the rim it is impossible to get it completely true. I have a gauge used to put on sprocket that got mine to within 1/16" either way. A 1/16" on one side when rolled around is 1/8" difference on the other. Without a spring tensioner you are constantly loose and tight. To me the tight is worse than the loose. I ran mine awhile with no tensioner but did not like the feel. If yours works thats good. I think the tensioner is the way to go for me.
 
Quieter Tensioner?

Has anyone come up with a way to build a tensioner that is quieter? I hate how much noise mine adds.....I attract attention riding under pedal power only simply because the tensioner makes so much noise.
 
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