Author Topic: Chain slack.  (Read 3551 times)

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Offline theslayedsaint

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Chain slack.
« on: April 24, 2016, 10:53:18 AM »
Has anyone tried to set your chain slack alone? If I recall right  there should be 3/4-1" of slack when the rider is on the bike. How can the task be done without being on the bike? Or is it just a two person job?
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Offline mystic_1

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Re: Chain slack.
« Reply #1 on: April 24, 2016, 11:31:06 AM »
You can use a ratchet strap to compress the rear suspension, or put some heavy objects on the seat.

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Offline theslayedsaint

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Re: Chain slack.
« Reply #2 on: April 24, 2016, 12:47:54 PM »
Ratchet strap is a good idea! Not sure how to apply the right amount of tension though
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Offline Davez134

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Re: Chain slack.
« Reply #3 on: April 24, 2016, 01:23:07 PM »
sit on the bike and measure the distance between the shock mounts with a tape measure. Then, use a ratchet strap to recreate that distance. Seems like that would do it.

JWExperience

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Chain slack.
« Reply #4 on: April 24, 2016, 01:31:38 PM »
Isn't the point of the slack to have room for suspension travel? Every road bike I've had I just gave around an inch of slack and been good there.


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Offline martin99

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Re: Chain slack.
« Reply #5 on: April 24, 2016, 02:26:38 PM »
Isn't the point of the slack to have room for suspension travel? Every road bike I've had I just gave around an inch of slack and been good there.


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I've always adjusted on the slack side too, on the understanding that the chain will tighten with the rider on the bike. Weirdly though, I've just replaced the chain and sprockets on my Yamaha SRX600 and the manual calls for 15-20mm without the rider. Can't say I'm too convinced, but it's what the (genuine) Yamaha manual says :-\
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Offline madmtnmotors

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Re: Chain slack.
« Reply #6 on: April 24, 2016, 02:46:03 PM »
Isn't the point of the slack to have room for suspension travel? Every road bike I've had I just gave around an inch of slack and been good there.


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Offline theslayedsaint

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Re: Chain slack.
« Reply #7 on: April 24, 2016, 03:27:44 PM »
Ok.... I'll give that a try and maybe have my wife set on it to see if it looks right.
1974 CB750 custom build cafe racer
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Offline brewsky

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Re: Chain slack.
« Reply #8 on: April 24, 2016, 03:41:40 PM »
Pull a string between the center of rear axle and the center of the front sprocket.
Adjust the rear suspension (with weight, straps or whatever), so that the center of the swingarm bolt hits the stringline.
That is when the chain will be at its tightest point.
Set the slack at that point.
It just so happens that on my 550, that match happens when the bike is on the centerstand.
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Offline strynboen

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Re: Chain slack.
« Reply #9 on: April 25, 2016, 12:40:02 PM »
try to turn the hveel..and thek the tension is konstant.
.i have seen some..go betveen teight and very Loose at one rotation..oval spokes can be a problem.
..you crash the bearings both in the engine and rearhveel if the thain get teight at any point...my 400 four had a bad fibaly bearing by a teight thail(..i think)
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Offline Chachi

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Re: Chain slack.
« Reply #10 on: April 25, 2016, 01:49:28 PM »
I also use the 1"method... 1" of slack with bike on center stand usually turns out to be 3/4" slack with me as rider.
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Offline theslayedsaint

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Re: Chain slack.
« Reply #11 on: April 25, 2016, 08:43:28 PM »
Ohh... Center stand so with no weight on he bike? I don't have a center stand so would a block under the kickstand work?
1974 CB750 custom build cafe racer
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-4-1 stainless exhaust
-GSXR front end

Offline seanbarney41

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Re: Chain slack.
« Reply #12 on: April 25, 2016, 09:51:14 PM »
just sit on the bike, reach down, and move the chain to see how much play there is
If it works good, it looks good...

Offline calj737

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Re: Chain slack.
« Reply #13 on: April 26, 2016, 04:21:03 AM »
just sit on the bike, reach down, and move the chain to see how much play there is
Exactly. Or have your wife measure...
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Offline PeWe

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Re: Chain slack.
« Reply #14 on: April 26, 2016, 04:31:59 AM »
You will get the feeling for it by experience.
Chain needs a little bit slack, a tensed chain can still be moved up-down. Too much slack and you'll here the chain  when shift gear
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Offline 70CB750

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Re: Chain slack.
« Reply #15 on: April 26, 2016, 04:39:22 AM »
just sit on the bike, reach down, and move the chain to see how much play there is

My method.  Or put 240 pounds of my son on it while I check  ;D

Offline Chachi

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Re: Chain slack.
« Reply #16 on: April 26, 2016, 06:03:35 AM »
I don't run with a center (service) stand -- but I keep one in the garage for maintenance. Pick one up on eBay or from someone on here. You can install in less than a minute and it makes basic service like chain adjustments, rear brake adjustment (even front brake adjustment) and oil changes a lot easier. It's just as quick to remove and you're back to where you were. There are other ways to do the chain slack adjustment, but the center stand would make it faster and easier (IMO) and it would help with a lot of other things as well. You just install with the pin/sleeve/long center bolt, no springs or anything. Add a cotter pin if you like. I just make sure it's on and skip the cotter, unless I'm doing more involved maintenance. And a block under kickstand would not get rear wheel off ground to spin for chain adjustment check (looking for tight spots, binding, etc.). Plus bike could tip over.
« Last Edit: April 26, 2016, 06:05:35 AM by Chachi »
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Offline theslayedsaint

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Re: Chain slack.
« Reply #17 on: April 26, 2016, 07:18:31 AM »
Yeah my bike is a little to "custom" for a center stand install I have one just can't put it back on... I'll go with the hey honey this should only take a mintue method...
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Offline CBDee

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Re: Chain slack.
« Reply #18 on: April 26, 2016, 11:04:14 AM »
Here's what Honda has to say: "Adjust to provide approximately 3/4 inch (20mm) of [minimum] chain slack at a point midway between the drive sprocket and the rear wheel sprocket. Rotate the wheel and recheck slack at other sections of the chain. Slack must not be less than 3/4 inch (20mm) at a point midway between the sprockets, regardless of the chain section at which measurement is taken"
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Offline przjohn

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Re: Chain slack.
« Reply #19 on: April 26, 2016, 12:05:16 PM »
Isn't the point of the slack to have room for suspension travel? Every road bike I've had I just gave around an inch of slack and been good there.


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Same here. I've never even heard of a bike that the manufacturer wants the chain slack measured with a rider aboard. That's why you have slack, to make up for the suspension arc. If you are leaving 3/4 - 1 inch slack with a rider aboard that chain will be too loose and may even start to slap around on the swingarm. Even dirt bikes that have way more slack and suspension arc than street bikes spec out measured on a stand.
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Offline przjohn

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Re: Chain slack.
« Reply #20 on: April 26, 2016, 12:18:40 PM »
From a 1973 750 Owner's Manual,

"Place the motorcycle on its center stand, with transmission in neutral."
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Offline Chachi

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Re: Chain slack.
« Reply #21 on: April 26, 2016, 12:34:41 PM »
Edit: Just re-read basic owner's manual:
Approximately 3/4" on center stand which decreases (less slack) with rider; make sure no less than 1/2" with motorcycle on wheels and laden with rider.

And shop manual is even more vague than owner's manual:
Slack on center stand should be 1/2" to 1".

So it's a range. I always went 1" on center to equate to about 3/4" with rider. I may just tighten mine up a little. 3/4" on center stand to hit 1/2" with rider.

To OP... are your tabs cut off for center stand install?
« Last Edit: April 26, 2016, 12:36:56 PM by Chachi »
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Offline theslayedsaint

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Re: Chain slack.
« Reply #22 on: April 26, 2016, 01:05:28 PM »
There not cut off but there also not able to install center stand to many thing in the way and onside is being used as a bracket for pipes.
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Offline PeWe

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Re: Chain slack.
« Reply #23 on: April 26, 2016, 01:19:47 PM »
I feel the slack with my foot, boot on. The chain must be easy to push upwards about 1 inch  in the area between rear and front sprocket where visible and possible to touch. All links on this side relaxed not stretching the other links. I do this with bike on center stand.

Sometimes a double check by a friend when I'm sitting on the bike or by my foot again. Chain must not has tension. When chain hits the center stand while riding the slack is too much

Important to roll the bike and feel same slack in increments of about 0.5m. If chain slack differ, chain need to be replaced, maybe sprockets too. Check on rear sprocket if chain can be lifted so half of the cogs can be seen under chain...
CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967