Chain slack allowance beyond the spec

[Sweaty_Doughnut]

My manual states chain slack of 30-40mm on the side stand. The chain has 1000 miles and I have a minor tight point where the slack is 25mm, while the rest of the chain is 30mm. Finding that perfect spot is such a pain as if it goes to 40mm of slack changing gears is not smooth. Is it ok to live it as it is?

[MarJay]

Wow what kind of chain is it that it hasn't lasted 1000 miles?

I'd make the tight spot about 35mm and go from there. Although, I've been riding for 22 years and never had any bike with what I would consider a tight spot on the chain, so either you're using a cheap OEM chain on a Chinese 125, or you're not lubing it enough.
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[Sweaty_Doughnut]

[jaffa90]

750cc Which bike?
Trail type bikes need more slack than most bikes so what slack have you when laden?

[stinkwheel]

Something you do with fixie bicycles is to find the tight spot, loosen the chainring bolts, whack the chain with a spanner then retighten them. That's because the chainrings are not a 100% perfect fit on fairly widely spaced bolts. It does reduce the amount of uneveness between the tightest and loosest spots.

I often wondered if you could do something similar with a rear sprocket and a bigger spanner.
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[MCN]

Tight spot is usually due to an out-of-roundness of a part of the transmission. A tight spot in a chain is easy to find as the chain will have a kink where the links are tight and resist free movement. There should only be a microscopic amount of tension due to the pressure from the seals. Tight spots are very difficult to move.
You can find the out-of-roundness in the sprocket by fixing a pointer to the frame or possibly on the ground. It has to be quite firm and substantial for better accuracy. Pointer touching the chain where it wraps around the sprocket and rotate the wheel.
Any out-of-round will be easily seen where the pointer doesn't touch the chain.
(You could pedant this check and use a DTI.)
The sprocket bolt holes are either not concentric or the teeth are not machined properly.
Who made the sprocket?

The slack is a tolerance anywhere between the measurements is acceptable (as far as OEM engineering is concerned).
A few mm outside won't be a show stopper but may mean more frequent check and adjustment.


https://youtu.be/StDoNy0q4Z0
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Disclaimer: The comments above may be predicted text and not necessarily the opinion of MCN.

[jeffyjeff]

[xX-Alex-Xx]

[Tankie]

This is where Scottoilers are worth their weight in gold.[/quote]
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[MCN]

[jaffa90]

Each to there own, at the end of the day you need chain slack when the bike is in use, more so over pot holes and bumps.

20 mm minimum slack (in the manual) on the xjr 1300 & 1200 bandit on the centre stand is too small as i have experience stretched chains years ago.

Watch them chains wagging away on the moto gp and world superbikes and they are going fast.

[Sweaty_Doughnut]

Thanks all. I have decided to re-adjust the chain and I'm more on the loose side now, around 38mm.

[Ste]

[jaffa90]

[Ste]

https://www.manualslib.com/manual/1161572/Yamaha-Xjr1300.html?page=67

[jaffa90]

[Ste]

The manual you linked to and the manual I linked to are for different bikes.

[jaffa90]

[Pigeon]