Chain question (NGC,obviously )

[Chuck in Indiana]

The Skorpion manual sez to put the bike on the side stand, and measure 30-40mm.
When checking the oil, it also says to put it on the side stand. .but it needs to be on the center stand to be correct.
So
How is a chain "normally " checked?

[Huzo]

Chuck it probably doesn't matter if you're on a mini bike or a Suzuki Hyabusa, one would think that you could not go wrong by loading the bike to normal level, then check the slack with it on it's wheels.
That is after all, where it does it's work.
Also, it's amazing how eccentrically some sprockets are churned out of the factory.
I once bought a rear sprocket for my Triumph Daytona 955 i and found the chain thrashed like combine harvester in use.
For the record, it was made by a mob called Sunstar, more like Uranus...!
I took it off and grabbed it by the outside in the lathe and clocked the inside mounting register, it was 15 thou' eccentric.
Not hard to fix, but the topic did come up when next at the shop.. 

[lucian]

Yep. bike on side stand,  30mm ,   vertical deflection at approximate center between sprockets on bottom chain links. I always move the bike back and forth once and check again. Should stay the same in all wheel positions.

[Lannis]

The Skorpion manual sez to put the bike on the side stand, and measure 30-40mm.
When checking the oil, it also says to put it on the side stand. .but it needs to be on the center stand to be correct.
So
How is a chain "normally " checked?

It's a bit by "feel", unless the manual has already taken all of the below into account and given you a "play" figure with the bike unloaded and on the sidestand.

Depending on the swingarm geometry of the bike you're checking, the chain will tighten up to a greater or a lesser degree when the swingarm pivots as you sit on the bike and the suspension compresses.   (A few bikes were designed so that the transmission output shaft and the swingarm pivot coincided, and the chain didn't change tension when the swingarm moved.)

The first couple of times I do it, I have someone who weighs similar to me (no comments from the peanut gallery please) sit on the bike while I set a comfortable amount of slack in the chain (maybe 3/4" of actual loose movement with finger pressure only at the middle bottom of the chain run).   Then I have them get off, and check the chain "feel" unloaded.  (or measure it if you're fastidious), and that's what I use when I'm on a trip, in the shop, or otherwise without a cooperative weight on the seat ...

Lannis

[Daniel Kalal]

How is a chain...

Chuck,
If you walk through the pits between races at a professional flattrack race, you'll see most everybody setting the chain slack by keeping the bike on the race stand, rotating the wheel while pinching the handle of a mallet between the chain and the sprocket--then pulling the wheel back to take out the slack, and then tightening things up (being careful to make sure the axle is exactly the same on both sides).  That's it.  I've never seen anybody measure anything.  These are guys who change sprockets and swingarm pivots between every heat.  Incidentally, the mallet is used to whack off the sprocket and brake disk with a quick-release hub.

[Guzzistajohn]

I do like Huzo sez on the tiger and KTM. But it does take a buddy to check it if he's not the same sized dude. I usually look for 1.5 to 2" deflection on the tiger and a little more on the KTM since it travels more.

[Guzzistajohn]

Chuck,
If you walk through the pits between races at a professional flattrack race, you'll see most everybody setting the chain slack by keeping the bike on the race stand, rotating the wheel while pinching the handle of a mallet between the chain and the sprocket--then pulling the wheel back to take out the slack, and then tightening things up (being careful to make sure the axle is exactly the same on both sides).  That's it.  I've never seen anybody measure anything.  These are guys who change sprockets and swingarm pivots between every heat.  Incidentally, the mallet is used to whack off the sprocket and brake disk with a quick-release hub.

Interesting Daniel, I'll have to give that a try 

[pehayes]

Hey Chuck, why title this "NGC".  I own two chain-drive Guzzis.  BTW, the old Italian manuals refer to measuring with the swingarm at "meta corsa" which would be halfway between max and min arc positions.

Patrick Hayes
Fremont CA

[Chuck in Indiana]

Thanks to all. .I think I have a handle  on it, now.

[LowRyter]

I have always had a centerstand on my bikes with chains.   Which is great to rotate the rear tire to find the tight spot in the chain. 

Then, (check or) adjust to 3/4 inch of slack at the tight spot and tighten the axle and done.  I also like to use a big reusable cotter key rather than bending a pin. 

I don't know what you do with a bike with no centerstand.  It's going to be a guess because you'll have a hard time finding the tight spot.  The book should say what the play it should have but I'd still go with 3/4 in or less, even on the sidestand.

And you know the chain is worn out when the chain is too loose when it's adjusted at the tight spot or you have no more adjustment left to tighten it (seldom happens) (although the "old school" guys would just take out a link   ).

And I found more chains have been worn out by over maintenance (over tightening) than neglect.  Most "o" ring chains need an adjustment after a couple hundred miles from new and perhaps every thousand or two thereafter.  Clean them with kerosene or WD40 (which is the same stuff) and if you wanna be neat, spray it with chain wax, smells good.

[Rough Edge racing]

 Bike swing arms generally or always move up and down on an arc...The chain is best adjusted when swing arm is at the "longest" position because of the "arc" And rotating the chain within this to find the tightest point..For all the street bikes I have owned it's done best with the rider seated on the bike and not on any stands... and about an 1-1/4 inch chain slack...Shifting problems on some bikes are because of a too tight chain..

[pyoungbl]

Bike swing arms generally or always move up and down on an arc...The chain is best adjusted when swing arm is at the "longest" position because of the "arc" And rotating the chain within this to find the tightest point..For all the street bikes I have owned it's done best with the rider seated on the bike and not on any stands... and about an 1-1/4 inch chain slack...Shifting problems on some bikes are because of a too tight chain..

Yes!  To elaborate, the swingarm arc means that the chain will tighten up until there is a straight line between the rear axle, swingarm pivot, and front sprocket (and then  get loose again as the suspension compresses until it bottoms out).  That might be the midpoint of the available arc, all depends on the motorcycle and how far the shocks will allow the swingarm to move.  It's usually too hard to get the suspension compressed enough to achieve the straight line alignment with someone sitting on the bike.  Most designs are setup so the rider is only compressing the suspension 20-30% with a seated rider.  As a result the manufacturer gives a slack figure based on having the bike on the side stand.  The amount of slack has been determined based on a pretty constant starting point (unladen bike on side stand) that is a known distance away from the straight line alignment.  1"~1 1/2" might be a common amount of slack (I just looked at my chain drive bike and the spec is 10~25mm, so .4" to 1").  The important point here is that you never want to have the chain completely tight, ever.  That will cause excess wear on the chain, sprockets, bearings and maybe even the transmission case.  At the same time you do not want the chain so loose it slaps the swingarm or jumps from the rear sprocket. 

[Tusayan]

The biggest issue with adjusting chain slack is a worn chain that varies in slack as it rotates.  The manufacturers figure applies to a new chain, typically with the rear suspension fully extended and any ride height adjustment set to the standard setting.

In an ideal world you would resolve all the issues by installing an unworn chain and sprockets, then remove the rear shocks, then lift the wheel/swingarms to the tightest point and set just a little slack in the chain.  That would then translate to an amount of slack that you could measure with the bike in the assembled and ready to ride configuration.  The real world tends to be a little less perfect and the main thing is not to overtighten (as others have said) because the countershaft bearing will not appreciate it one bit.  Having inadvertently run chains too tight any number of times, it amazes me what that bearing will put up with, but better not to press your luck.

In a really perfect world you could ride a Bimota SB2 that placed the swingarm pivot outboard and concentric with the countershaft.  With an unworn chain, that design leaves tension unchanged as the suspension moves through the full range of travel 

[LowRyter]

let's overthink this now.

[kballowe]

I give it about a 3/4" deflection when changing a tire.
Otherwise, (on the side stand) a bump with the end of my boot usually suffices to check the "tension"

[redhawk47]

I don't know if chains would wear unevenly, but I do know that sprockets can be manufactured/mounted off center.
So, the first step is to find where the chain is the tightest: easiest on the centerstand or a jack, but can be found by rolling the bike around the shop.
Second step is to adjust the chain to the manufacturer's spec with the chain at the tightest position. If they say "on the sidestand" they have calculated the change in length as a result of the swing arms arc. I try to get it to the low value.

BTW: I have had several chain driven bike that had a "wa-wa" at speed - I thought it was the engine pulsing, but there was no indication of that on the tach. I finally figured out that it was an off-center sprocket and the chain was going loose to tight.
PS: I think I heard a similar "wa-wa" sound from my V7II the other day. That could be caused by the single U-joint working at an angle.

[Tusayan]

I don't know if chains would wear unevenly, but I do know that sprockets can be manufactured/mounted off center.

I’d agree about uneven chain wear except that new chain and sprocket sets do not in my experience vary in slack as they’re rotated, and worn sets do.  Something changes.  I guess for the purposes of this thread it’s not that important what changes exactly but it would be interesting to know - I wouldn’t claim to have that figured out.

[LowRyter]

I’d agree about uneven chain wear except that new chain and sprocket sets do not in my experience vary in slack as they’re rotated, and worn sets do.  Something changes.  I guess for the purposes of this thread it’s not that important what changes exactly but it would be interesting to know - I wouldn’t claim to have that figured out.

that's been experience.  Everything is fine with a new chain and sprocket. 

And I've learned that regardless how the sprockets look, go ahead and replace them with a new chain.  Instead of getting 20-25k miles out of it, it's done in 10.

[Vagrant]

And not one person reminded you to have it in neutral! I once watched a over heated Bmw rider loosen his adjusters all the way in with still no slack. I almost felt bad telling him.

[LowRyter]

And not one person reminded you to have it in neutral! I once watched a over heated Bmw rider loosen his adjusters all the way in with still no slack. I almost felt bad telling him.

BRILLIANT !

[Chuck in Indiana]

that's been experience.  Everything is fine with a new chain and sprocket. 

And I've learned that regardless how the sprockets look, go ahead and replace them with a new chain.  Instead of getting 20-25k miles out of it, it's done in 10.

So while I have you guys attention.. are sprokets standard? It's not like I can just go to my MZed dealer and get some new ones..

[lucian]

I like these guy's 

  https://www.bikebandit.com/blog/how-to-choose-motorcycle-sprockets

[Murray]

The Skorpion manual sez to put the bike on the side stand, and measure 30-40mm.
When checking the oil, it also says to put it on the side stand. .but it needs to be on the center stand to be correct.
So
How is a chain "normally " checked?

After dealing with a few "intresting" descriptions how how to check tension from various manufacturers I got  this bit of advice. Sit on the bike the bottom of the chain at the mid point between the sprockets should have 10-20mm free play. On a road bike 20mm is a bit too much but it puts you in the zone.

[Tusayan]

So while I have you guys attention.. are sprokets standard? It's not like I can just go to my MZed dealer and get some new ones..

JT Sprockets has them for just about anything.

http://www.jtsprockets.com/fileadmin/files/JT%20Sprockets%20Application%20Guide%202018.pdf

[Tusayan]

Sit on the bike the bottom of the chain at the mid point between the sprockets should have 10-20mm free play. On a road bike 20mm is a bit too much but it puts you in the zone.

Follow the manufacturers guidance for the specific bike.  20-mm of free play on (for example) an ST Ducati under that circumstance would be likely rigid at the tightest spot in the suspension’s range of motion, unless you were very heavy. With a brand new chain, the spec for that particular bike is 30-mm free play on the centerstand, and it needs to be a bit looser than that if the chain is nearing the end of its service life.  This feels very loose until you check it with rider, passenger and bags (which tends to be close to the tightest spot) and find it’s tight!

[Chuck in Indiana]

JT Sprockets has them for just about anything.

http://www.jtsprockets.com/fileadmin/files/JT%20Sprockets%20Application%20Guide%202018.pdf

Kool. Thanks 

[SED]

Cheap standard steel and aluminum sprockets with center hole.  You cut the ID and the bolt holes.  Got one for the slicer.

http://www.pbisprockets.com/

https://www.shop.pbisprockets.com/category.sc?categoryId=56

[LowRyter]

So while I have you guys attention.. are sprokets standard? It's not like I can just go to my MZed dealer and get some new ones..

In my experience they are.  At least they are widely supported in the aftermarket. 

To your point, it could be a challenge chase down the right one for the MZ.  It might take a little mixing and matching to figure the cross reference.  And if MZ changed out wheel or brake sets in mid model production, it could be another challenge. 

[Rough Edge racing]

 If it's a flat sprocket ,Rebel Gears will make most any size with the holes you specify for around 60-75 bucks.....In land speed racing, the best way to slow your bike down a bit is with a too tight chain..Just like timing belts, a bit loose is better than a bit tight.. On bike with the final drive transmission sprocket behind the clutch like older Brit bikes and Harley big twin, a tight final drive chain (or belt) tries to tighten the primary drive chain and creating another problem..

[twowheeladdict]

Some additional thoughts.

Don't forget to check chain alignment.  I like the Motion Pro Chain Alignment tool.
Don't forget to measure the stretch in the chain at several locations.

If you are going to get new sprockets and chain make sure they are a matched set meaning that they are of like strength ratings.  A drag race chain with an aluminum sprocket set will mean quickly worn sprockets.

All of the above is one of the main reasons I am now on a Moto Guzzi V7.