Chain Adjustment - Slightly Confused

[JimmyTheDriver]

Forgive me in advance for what I belive is a silly question...

I have done a bit of research, including watching videos, and I can't seem to get comfortable with the proper chain tension.  They tend to breeze over the actual setting of the tension part, and focus on how to get to that point.

So - spanner wrench in hand, I took a look at the diagram on the SSA of my 2007 Monster S4R.  What on earth am I measuring? 

I understand I want 30-34mm of travel, but from what?  The picture leads me to believe it is from the bottom of the swing arm to the middle of the chain, maybe?  Or is it 30mm of travel from the bottom, sag position of the chain to however high I can lift it?

Any advice would be great!  Sorry for the not so technical explaination.  I swear I am competent enough to do it, I just need to figure out what I am measuring.

Thanks!
Jimmy

[numbskull]

It's this:

"30mm of travel from the bottom, sag position of the chain to however high I can lift it"

Make sure you roll the bike a bit to get the most slack on the chain before measuring it.

[JimmyTheDriver]

Ah ha!

It's probably appropriate that a member named "numbskull" replied to this.

Thanks,
Jimmy

[Speeddog]

Per the Owner's Manual:

"Move the motorcycle slowly until you find the point at
which the upper section of the chain is most taut.
Place the motorcycle on its sidestand. Push the chain
upwards with a finger in correspondence with the centre
of the swingarm (see adhesive label). The bottom run of
the chain must be able to deflect 30 to 32 mm."

[WhiteStripe]

I spent some time really over thinking this in the spring.

Here is a links to one of my posts that may be helpful to you.  Were a couple other on same topic.

You are on the right track - its not rocket science.

http://ducatimonsterforum.org/index.php?topic=37434.msg660023#msg660023

[ScottRNelson]

This all sounds a bit different from what I do.

I grab the chain at the bottom, half-way between the front and back sprockets, lift it up, then push it down and measure the difference.  That's how the diagram shows it right on the swingarm.

Some of you seem to imply that you measure at the resting position then lift up and measure, which is going to give you a looser chain.

If this is wrong, I would like to know so that I can start doing it correctly.

I notice this has been discussed before and there was not agreement: http://ducatimonsterforum.org/index.php?topic=40707.0

In looking at the service manual for the ST2, it seems to imply that you measure the resting position, then push up to get your measurement.  It is worth finding out from an authoritative source on this.

[Speeddog]

Here's the similar text from an '02 S4 manual:

"Turn the rear wheel slowly until you find the position
where chain tension is highest.
With the motorcycle on the side stand, push the chain up
pressing with a finger at the point where it intersects
with swing arm centerline. The lower portion of the chain
should have a slack as follows (fig. 34.1):
25-27 mm."

Typically, the SSS-equipped bikes will give a measurement from the bottom swingarm surface to the chain pin centerline.
This is due to the fatness of the swingarm... you can't push the chain up enough to get it tight.

For example, from an 848:

"Chain tensioning (on sidestand): hold a rule half way along the
bottom run of the chain, push down on the chain and adjust
the tension until the distance between the aluminium of the
swingarm and the centre of the chain pin is 31 to 33 mm."

[ducpainter]

It's this:

"30mm of travel from the bottom, sag position of the chain to however high I can lift it"

Make sure you roll the bike a bit to get the most slack on the chain before measuring it.

Actually that is incorrect.

You want the tightest portion of the chain to have the specified free play.

There have been many bent output shafts doing it your way.

[numbskull]

If it's tight on the upper part of the chain (above sprockets), wouldn't the lower part of the chain have more slack? I should go and double check my chain when I get back home. Thanks, Ducpainter!

[ScottRNelson]

If it's tight on the upper part of the chain (above sprockets), wouldn't the lower part of the chain have more slack?

Yes, but so?

That just means that you need to rotate it around until that tight part is on the bottom when you take your measurement.

[numbskull]

Ah, I see. I was doing it in reverse all along then. I was making sure it was tight on the top, slack on the bottom when I was measuring. Thanks.

[floyd turbo]

No you were right.  You always want it tight on top and loose on the bottom.  But you want at the tightest spot on the slack(bottom) side.

[ScottRNelson]

No you were right.  You always want it tight on top and loose on the bottom.  But you want at the tightest spot on the slack(bottom) side.

What you've said here doesn't make sense.  You want it tightest wherever you're moving the chain to measure it.  And since you measure on the bottom, if you're following correct procedures, you want the tightest part of chain on the bottom where you're moving it.

When I'm looking for the tight spot, I rotate the wheel about 1/4 turn then move the middle of the bottom part of the chain up and down.  Then I rotate again and move it again to see if it's tighter.  I repeat until I've checked the whole chain and found the point where it moved the least.  Then that's where I make the measurement for correct chain adjustment.

[floyd turbo]

I was trying to clarify the difference between the tight(top)  side of the chain and the tightest spot in the slack (bottom) side of the chain.  I guess I only added to the confusion.

[ScottRNelson]

I was trying to clarify the difference between the tight(top)  side of the chain and the tightest spot in the slack (bottom) side of the chain.  I guess I only added to the confusion.

The top is only as you're describing it when you're actually riding the bike and applying power.  When the bike is parked with the engine off both sides should have approximately the same tension.

In any case, I've learned something from this thread and will modify how I adjust the chain on my Ducati from now on.