Author Topic: CB400F Drive chain adjustment  (Read 142 times)

Offline mattsz

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CB400F Drive chain adjustment
« on: August 01, 2020, 12:27:27 AM »
All my sources say to put the bike on the center stand (rear wheel off the ground) and adjust for a 3/4" range of vertical movement midway between the sprockets.  This seems tight compared to other chain-driven bikes I have or have had.

But wait... my owners manual says to move the chain up and down to observe the 3/4" slack.  The Honda shop manual says to check the chain tension by finger-depressing the chain midway between sprockets and measuring the sag.  Setting this push-only sag at 3/4" will yield very different tension than the up/down 3/4" setting.  And ever helpful, the Haynes manual simply says, "The chain is correctly adjusted when, with the machine on the centre stand, there is 20mm (3/4 inch)."  This doesn't even make sense.

What do you guys generally do?

Offline K2-K6

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Re: CB400F Drive chain adjustment
« Reply #1 on: August 01, 2020, 07:43:58 AM »
If you can't be confident that the information is giving you the best outcome,  it can be verified for any bike as follows;- bike on stand, ratchet strap from swingarm over frame to other side of arm,  pull suspension up until sprockets and swingarm pivot are all on the same plane,  set chain to have 13mm (1/2 inch) ot total movement like that as this is the tightest it'll get.

Now lock it off,  release strap,  and measure what you've got with the suspension hanging loose. Write it in your manual with a note for future reference.

Always did motor-X bikes like this as they moove so far,  gets minimal slack without pulling the bearings into load as it moves.

Offline mattsz

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Re: CB400F Drive chain adjustment
« Reply #2 on: August 01, 2020, 11:47:19 AM »
That certainly sounds do-able... still curious how others interpret the differing instructions, though.

I have two Kawasaki W650 service manual editions - a print 2002 version which visually indicates only "flexing" the chain in one direction, and a digital 2005 version which has been changed to clearly indicate using the full up-down range of motion.  The accompanying text, and the measurement spec, is the same for both.  So it seems that 25 years after Honda couldn't figure out how to check drive chain tension, Kawasaki still hadn't cracked it...

 

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