Chain slack

[revsplinter]

So manual goes to say chain slack is 25-32mm at the end of chain guide. Then goes on to say that 3 fingers is close. 25 to 32 is way too tight and three fingers is no where near 25 to 32. 45 to 52 seems close to me. Is this just labeled wrong?

 

[RobA321]

Thought the same. Took shock off and ran the swingarm thru the travel to check the spec.

 

[Foss]

Better to have a loose chain than over tighten. I rather swap out sprockets than fix a countershaft.

 

[RobA321]

I thought loose was better but got derailed 2nd ride with the 3 fingers spec

 

[Upinsmoke57]

That also confused me. Their fingers must be really thin over there. Either way due to the location of the front sprocket relative to the swingarm pivot the slack can be reduced a fair amount compared to a typical KTM. I am around 1.25". But if you're really paranoid remove the shock to see what the magic number is and maybe make a block of wood to test it after that.

 

[Theo]

After my first trackday I measured the slack and it was as per the manual, roughly 30 mm above the chain slider top bolt.
EDIT: I meant that after my first trackday the chain, with the rear end lifted on the center stand, could be pushed upwards until it left a space of 30 mm between itself and the top screw of the chain slider.
I keep it looser than that but I still can't slide three fingers; I just make sure that my left index, middle finger and ring finger can't pass when my hand is at the end of the chain slider and aside it, like here:

If I want to tighten the chain, I remove the rocker arm to pullrod shaft and the rocker arm to shock shaft, like in this video, to make sure that it's not too tight:

 

[ReVolter]

I use this handy gauge I printed based on the specifications. Works great; no chain slap.

 

[Voozee]

I use this handy gauge I printed based on the specifications. Works great; no chain slap.

Thanks ReVolter,
Just printed it out myself. I read your other post about how to use the reference mark and tried it out on my bike. I am still about 5mm above the 32mm mark. I know its the spec but it just seems insanely tight. When you set yours, is your chain so tight on the 25m notch that it wont jump to the 32mm notch?

 

[ReVolter]

Yup. I know it seems a bit tight, but it works. I'm not right at the minimum mark, but not over the max. The chain runs nice and quiet. I used the printed specs. to design it. I had one for my CRF450. Before I used it there I had no idea I could ride without chain slap.
You can lie on the seat and compress the suspension to maximum extension an note that the chain is not actually that tight.

 

[Voozee]

Awesome thanks for clarifying. Ill give it a shot.

 

[ReVolter]

Let me know what you think of it.

 

[Voozee]

Let me know what you think of it.

Seems pretty close when I hold it directly behind the chain guide. Could you confirm these measurements when you have a chance.

 

[ReVolter]

From the manual: "Measure if the chain slack is around 25-32 mm (1 – 1.25 inches) at the end of the chain guide."
This means +/- 12.5mm to 16mm above and below the reference (centre line), which should be 0 deflection (pull the chain taught on the bottom).
So, 20.5+12.5=33, and 20.5+16=36.5 which is what you measured. The reference should just touch the chain near the end of the chain guide if you are using the standard sprocket with the chain tight. I know it seems a bit weird at first. My chain was very slack from the factory, but these x-ring chains are very stiff when new.

 

[Voozee]

Ahh... understood. Thanks for the detail. Helps a lot.

 

[Voozee]

Here is the final product using ReVolters tool. Chain sits comfortably on the 25mm notch, and if I pull hard I can get it to just get it to slide onto the 32mm notch. From a finger prospective, I can only get two fingers w/small gap in right behind the chain slider. This is tight as I can bring myself to run the chain. Just inherently feels wrong but i know its the spec. When the bike is on the ground and I compress the rear suspension close to the max extension of the swing arm the I can just barely move the chain up and down. its tight but not rock solid.

 

[Ross Shafer]

just to verify, this is done with wheel unweighted off the ground, correct? Thanks in advance!

 

[Voozee]

just to verify, this is done with wheel unweighted off the ground, correct? Thanks in advance!

Yes this is done on OEM Stand. Bike completely unweighted.

Hopefully ReVolter can chime in and confirm his measures similarly

 

[Ross Shafer]

Gracias!