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[roadrich]

Just installed the chain kit on my 2018 Zero FX.  How much slack should the chain have?  I only found one video that said "about 1 inch" but would like to know if Zero has a specification for this.  Thanks!

[BrianTRice@gmail.com]

Most chain-driven motorcycle manuals call for 0.8-1.2in (22-28mm) of slack, and actually I'm just recalling V-Strom 650 recommendations with an O- or X-ring chain.

Zero hasn't published any recommendations that I'm aware of.

Here are some generic recommendations that suggest it's more of a judgement call about how the bike will be ridden:
https://www.cycleworld.com/2015/08/28/cycle-world-tips-and-tricks-how-to-check-and-adjust-your-motorcycle-chain/

Just remember that chains get looser as they wear and lose oil for O-ring or X-ring chains, but Zero's chain kit doesn't have rings apparently, so I don't know.

[Richard230]

Disconnect the shock so that you can move the swing arm up and down to find the chain's tightest point, likely when it is parallel with the ground' and still has a small amount of slack.  That will be where the chain should be set so that it will not be too tight under all conditions.  Measure the slack after reconnecting the shock and that will be the amount of slack that you will want to record for future adjustments and checking.

[BrianTRice@gmail.com]

Disconnect the shock so that you can move the swing arm up and down to find the chain's tightest point, likely when it is parallel with the ground' and still has a small amount of slack.  That will be where the chain should be set so that it will not be too tight under all conditions.  Measure the slack after reconnecting the shock and that will be the amount of slack that you will want to record for future adjustments and checking.

Doesn't the concentric pivot of the swingarm and motor / front sprocket make this mostly a redundant test?

I would guess that really the only concern is how much jerk the chain will experience under dynamic load.

[JaimeC]

Thank you, Brian.  You beat me to it.  Unlike most other motorcycles, the swing arm pivot is exactly in line with the output sprocket so the chain will NOT change tension as the suspension moves through it's travel.  The reason most motorcycles have slack in the chain is to allow for the differing lengths of the chain travel due to suspension movement.  This doesn't happen on a Zero.  Don't make it too snug that it puts strain on the motor and wheel bearings and you'll be fine.

[Richard230]

Thank you, Brian.  You beat me to it.  Unlike most other motorcycles, the swing arm pivot is exactly in line with the output sprocket so the chain will NOT change tension as the suspension moves through it's travel.  The reason most motorcycles have slack in the chain is to allow for the differing lengths of the chain travel due to suspension movement.  This doesn't happen on a Zero.  Don't make it too snug that it puts strain on the motor and wheel bearings and you'll be fine.

That is right. I had forgotten about Zero's rational design.   Use my system of determining the appropriate chain slack for all other chain-driven motorcycle brands.   

[roadrich]

Awesome, thanks everyone.  I set it around 3/4" slack for now.  If I wasn't worried about snapping the belt in the middle of a forest, I would have probably stuck with the belt drive.  It is noticeably louder.  Not horrible but no more sneaking up on pedestrians.

[BrianTRice@gmail.com]

I've updated the unofficial chain kit guide with maintenance notes, thanks:
https://zeromanual.com/wiki/Chain_Kit