Need help measuring chain slack (again) - Honda RC51 Forum : RC51 Motorcycle Forums
Reply
 
LinkBack Thread Tools Display Modes
post #1 of 11 (permalink) Old 07-31-2012, 06:50 PM Thread Starter
Junior Member
 
Corsair's Avatar
 
Join Date: Mar 2010
Location: Appleton, WI
Posts: 29
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
Need help measuring chain slack (again)

This will be my second chain adjustment on the bike since ownership of it. The first adjustment I did after the dealer put a new chain and sprocket on it ~920 miles ago. The rear axle wasn't equal on both sides of the swingarm so while I was fixing that I gave the chain a bit more slack because the previous chain from the original owner ran too tight. I didn't want to repeat history. Bike has 8,xxx miles BTW.

Last adjustment I did I thought I set the slack to 1 1/4", because I measured the highest part of the slack at the top of the side plate, and then I measured the lowest part of the slack at the bottom of the side plate. I remember that the chain didn't touch the swingarm, the entire up and down slack was between 15mm and 50mm as shown on the tape measure.

The Honda manual says measure slack from the up and down movement of the roller pins. A nice video from Canyon Dancer showed them measuring from the top of the side plate at both the lowest and highest points in the slack. I wonder now if my original was more like 21mm instead of the 35mm!

Question #1 - Do you measure the slack from the same fixed point on a chain, i.e. the center of the roller pin or the top of the side plate?

Question #2 - Based on my photos, I can't even move the chain high enough before hitting the swingarm to tell what the slack is. In the first photo below, measuring from the center of the roller pin (~48-49mm) at the lowest (and tightest part of the chain), when I lift the chain up I have just barely any resistance up until the chain meets the swingarm. In the second photo, that's 15mm, so my total slack up to hitting the swingarm is ~33mm.

Am I doing this wrong on this motorcycle? The chain is so close to the swingarm already that it seems to be difficult to know where it would have stopped if the swing arm wasn't in the way. According to my measurement, I'm technically still within spec. Without really having much resistance though, I'm not sure if the swingarm wasn't in the way what my slack would truly be.

I suppose if the chain slack increased so the roller pin was at 55 mm on the tape measure then my slack up to the swing arm would be >35mm and it'd be time to adjust.

Am I missing something here or am I really doing this right? Is my chain too loose as shown?









Lastly, I shot a pic of the inside of the rear sprocket. The upper edges of the teeth seem a bit more scratched up than the outside edges, but I'm not sure if this was caused by that slight misalignment of the rear axle until I fixed it or if that's a symptom of chain slack. The chain and rollers have zero wear to them.



Sorry for the long post. I've just been really hung up on trying to check chain slack on this thing, and I really need some help from you guys.

Thanks
TC
Corsair is offline  
Sponsored Links
Advertisement
 
post #2 of 11 (permalink) Old 07-31-2012, 07:09 PM
Lifetime Premium
 
madbuyer's Avatar
 
Join Date: Sep 2010
Location: Indy
Posts: 8,335
Mentioned: 17 Post(s)
Quoted: 226 Post(s)
Put the bike on the ground for a better reading.



The very first schoolbook that was written had God all over it. --Dave Mustaine
madbuyer is offline  
post #3 of 11 (permalink) Old 07-31-2012, 07:21 PM
Senior Member
 
Join Date: Jul 2011
Location: Yuma, AZ
Posts: 169
Mentioned: 0 Post(s)
Quoted: 1 Post(s)
It's probably too loose if your "low" measurement is with the chain just dangling freely with its own weight. You need to pull the chain down as far as you can with your hand for that portion of the measurement. Also, as madbuyer said (and I'm fairly sure this is stated both in the owner's manual and on the sticker that describes chain slack on the swingarm), you should be doing these measurements with the bike on the sidestand.

2008 Ducati Monster S2R1000 (the mod whore)
2003 RC51 (sold)
2002 ZX-7R (sold)
Crarrs is offline  
 
post #4 of 11 (permalink) Old 07-31-2012, 08:45 PM
Senior Member
 
jondog9's Avatar
 
Join Date: Aug 2010
Location: Northern CA
Posts: 8,653
Mentioned: 15 Post(s)
Quoted: 317 Post(s)
As your swingarm moves up and down, so changes the tightness of your chain a little. I have my tire on the ground when getting that final measurement.
You've figured everything out by your description.
Measure from center of the rivet each time. Make sure you're at the same point on the underside swingarm.
I was advised by a pro 25 to 30mm of slack.
In my pictures, I'm at 17mm and 46mm, about 29mm of slack.
Attached Thumbnails
Click image for larger version

Name:	DSCF0006.jpg
Views:	471
Size:	88.0 KB
ID:	3301   Click image for larger version

Name:	DSCF0007.jpg
Views:	421
Size:	91.3 KB
ID:	3302  

John, 2000 RC51 #000100

jondog9 is offline  
post #5 of 11 (permalink) Old 07-31-2012, 10:11 PM Thread Starter
Junior Member
 
Corsair's Avatar
 
Join Date: Mar 2010
Location: Appleton, WI
Posts: 29
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
jondog9, when you lift the chain up for the top slack measurement, is your slack tight enough as shown in your picture that it resists touching the swingarm? And, as Crarrs mentioned, on your down measurement you're apply (some level) of pressure until the chain resists (i.e. not under it's own weight?)

I read a lot about setting it to 1" - 1 1/4". Seems like the 1" is accomplishable, but 1 1/4" doesn't seem realistic given how close the chain already gets to the swing arm and measuring from the pins. Guess I won't know until I try vs. my previous measurement from top and bottom of the side plates. I keep referencing the distance between the swinger and chain because, coincidentally, I looked at a Yamaha R6 in a parking lot tonight and they have all the space in the world around the bottom chain run!

As for the rear stand vs. side stand, I won't debate that. I'll mention in the last couple of times I checked tension, especially after the chain/sprockets were replaced that my measurements were pretty much identical whether on the side stand or rear stand. That was even with preload down to 1. It seemed to me all I was doing with the rear stand was rotating the 'triangle" which didn't affect the slack versus modifying the lengths of the "triangle" with any kind of weight change that would affect the slack measurement.
Corsair is offline  
post #6 of 11 (permalink) Old 08-01-2012, 08:46 AM
Senior Member
 
jondog9's Avatar
 
Join Date: Aug 2010
Location: Northern CA
Posts: 8,653
Mentioned: 15 Post(s)
Quoted: 317 Post(s)
Quote:
Originally Posted by Corsair View Post
jondog9, when you lift the chain up for the top slack measurement, is your slack tight enough as shown in your picture that it resists touching the swingarm? And, as Crarrs mentioned, on your down measurement you're apply (some level) of pressure until the chain resists (i.e. not under it's own weight?)
I don't think it touches the underside of the SA.
I measure slack at the middle point, between the front and rear sprocket. I put a little pressure upwards and equally so downwards. I think that's important.

Quote:
Originally Posted by Corsair View Post
I read a lot about setting it to 1" - 1 1/4". Seems like the 1" is accomplishable, but 1 1/4" doesn't seem realistic given how close the chain already gets to the swing arm and measuring from the pins. Guess I won't know until I try vs. my previous measurement from top and bottom of the side plates. ...
I use mm anytime I can. It's just easier I think. You have mm on your tape measure too.
I don't know about the 1in._1-1/4in. thing unless I do the conversion, but if I look closely at my own pictures, my slack is 1-1/4in.

I've never heard of using two different reference points when trying to gauge any kind of a gap, or in this case, slack. Keep it simple, use the center of the chain pin.

John, 2000 RC51 #000100

jondog9 is offline  
post #7 of 11 (permalink) Old 08-02-2012, 01:05 AM
Lifetime Premium
 
MakisRC51's Avatar
 
Join Date: Jan 2012
Location: Korinthos, Greece
Posts: 3,239
Mentioned: 15 Post(s)
Quoted: 77 Post(s)
When you work in a workshop and you have to adjust 30-40 chains a day, you cannot measure the slack with a measuring tape.
Thus we follow the rule that says:

You press the chain against the swingarm at the point that it touches (barely) the end of the slider's underneath



If the chain lift's itself (even a bit) from the the slider's upper side, it is more than ok.

However in supersport bikes, that doesn't always happen (depending on the swingarm's design) so I just make sure that the chain barely touches the edge of the slider's underneath side.
I press it against the slider, touching it, I start adjusting the swing arm pulling the chain some more, until it is ready to stop contacting the slider (but while it still does) and that's just OK.
Then make sure both sides of the rear axle is equal distanced by it's marked blocks.
If you need to adjust the RH side adjuster then you should check the chain's side adjuster again by the same way described above. Finally you tight the axle up and you're ready to go.


My Íhlins Project: https://www.rc51forums.com/forums/showthread.php?t=6033
Quote:
Originally Posted by SubSailor View Post
Congratulation to MakisRC51 for winning the 2014 Bike Of The Year Contest!
MakisRC51 is offline  
post #8 of 11 (permalink) Old 08-02-2012, 08:10 AM Thread Starter
Junior Member
 
Corsair's Avatar
 
Join Date: Mar 2010
Location: Appleton, WI
Posts: 29
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
With the info from jondog9 and MakisRC51, I got it squared away last night. I can definitely see that if the chain is tightened as such that it's any further away from the slider than a couple mm that the overall slack setting ends up being too tight (~25mm or less).

Last question after I did my chain last night-- do you guys have a rule of thumb on rear shock preload when adjusting? Do you adjust it with the preload you normally ride with? I adjusted the chain at the 1 setting (lowest), but when I sat on the bike and leaned over to check the slack I thought it was a bit more taught than I wanted. I moved the preload up to 5 and it was closer to where it was just after I finished the adjustment. This is okay, as I personally cannot tell the difference too much between 1-5, and I adjust it up to 8 or 9 when my wife rides 2-up with me.

Thanks for the info so far, it has finally answered a few questions for me!
Corsair is offline  
post #9 of 11 (permalink) Old 08-02-2012, 08:52 AM
Senior Member
 
jondog9's Avatar
 
Join Date: Aug 2010
Location: Northern CA
Posts: 8,653
Mentioned: 15 Post(s)
Quoted: 317 Post(s)
Seems like that's putting the cart before the horse, sort of. I would set my suspension preload, then set the chain slack.
That's why I said I have my tire on the ground, and measure chain slack while the bike is on the sidestand. As the swingarm moves up, and the shock compresses, your chain slack tightens up a little.

John, 2000 RC51 #000100

jondog9 is offline  
post #10 of 11 (permalink) Old 08-02-2012, 09:20 AM Thread Starter
Junior Member
 
Corsair's Avatar
 
Join Date: Mar 2010
Location: Appleton, WI
Posts: 29
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
Well, two thoughts I had about it.
  1. The setting of the preload, even on the side stand, may affect the "triangle" and as such your slack measurement.
  2. Even if the preload setting doesn't affect that "triangle" significantly, it definitely changes how much the shock compresses once there's weight on the bike. But again, just on the sidestand the measurements seem like they could all be similar until you weight load the bike.

So for example, if chain tension on the sidestand was measured nearly the same between preload 1 and 5 after adjustment, once you sit on the bike the chain would definitely have more tension under 1 than it would under 5.
Corsair is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Honda RC51 Forum : RC51 Motorcycle Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome