Chain slack! Please advice!!

[ninot7]

My WR chain is set at 43mm (owners manual states 40-45 mm for WR) but it seems a bit tight. All adjusted as per instructions and measurements taken accordingly. Gear changes fine and no gear whine. 
Are people following the manual for chain slack?

[Uncle M]

I followed the manual instructions since bike was new. Just installed third chain; second one wasn't stretching (at 52,000 km) or showing any other signs of being worn out but this year's travel plans made doing it now make sense.

[ninot7]

8 minutes ago, Uncle M said:

I followed the manual instructions since bike was new. Just installed third chain; second one wasn't stretching (at 52,000 km) or showing any other signs of being worn out but this year's travel plans made doing it now make sense.

Nice one thanks. 
Yamaha do like their chains tight across the range. 

[ninot7]

Also was wondering how the chain guide affects measuring the slack?

[williestreet]

I do not follow specs.

 

When the bike was new I removed shock and moved the swingarm through it complete range of motion.  Checking slack as I went it was too tight when at it furthest point in my opinion.  I run 50-51mm.  

 

A tight chain is hard on the chain, sprockets, countershaft bearings and prevents the suspension form moving through it's complete range of motion.

A loose chain is a happy chain and as long as you don't go stupid loose will not hurt anything.

 

 

 

 

[williestreet]

4 minutes ago, ninot7 said:

Also was wondering how the chain guide affects measuring the slack?

Chain guide restricts movement.  

You can't measure slack normally when running a chain guide.  Your measurements will not be accurate.

 

My suggestion would be to adjust and set your slack without the chain guide.  Then you need to find somewhere else to measure slack that is not affected when the guide is mounted.

 

My method is to make a spacer I use above the swingarm, just in front of the chain guard.  

I slide my spacer in to check slack.  If too loose I make the required adjustment.

 

My spacer has 2 widths.  The larger when measuring below in the normal position, the smaller as shown when checking above.

 

 

 

 

[ninot7]

9 minutes ago, williestreet said:

I do not follow specs.

 

When the bike was new I removed shock and moved the swingarm through it complete range of motion.  Checking slack as I went it was too tight when at it furthest point in my opinion.  I run 50-51mm.  

 

A tight chain is hard on the chain, sprockets, countershaft bearings and prevents the suspension form moving through it's complete range of motion.

A loose chain is a happy chain and as long as you don't go stupid loose will not hurt anything.

 

 

 

 

Good to know. I’ll slacken it up tomorrow and give it a run. 

[Uncle M]

1 hour ago, williestreet said:

I do not follow specs.

 

When the bike was new I removed shock and moved the swingarm through it complete range of motion.  Checking slack as I went it was too tight when at it furthest point in my opinion.  I run 50-51mm.  

 

 

@williestreet did same thing when I first got the bike. Then following manual instructions, set slack at 47-48 mm. Happy chain and sprockets!

Edited April 5, 2023 by Uncle M

[Black99S]

2 hours ago, williestreet said:

I do not follow specs.

 

When the bike was new I removed shock and moved the swingarm through it complete range of motion.  Checking slack as I went it was too tight when at it furthest point in my opinion.  I run 50-51mm.  

I did the same - tightest point is when centrelines of front sprocket shaft, swingarm pivot and rear axle are in line. I run the Yamaha chain guide. 

With bike on centre stand or lift I can check with ruler 45mm (1¾") or just push up gently on the chain - if chain just touches rear of slider I'm good,