chain slack

[michael1954]

Thanks Max. So, just thinking out loud here (I’m clearly not going to do it). By Honda setting the limits as 1” to 1 1/4” in theory it only NEEDS to be 8mm (sorry for mixing measurements BTW) to allow sufficient slack in the drivetrain before it locks up.

In other words there is a decent safety margin built in here so unless you do your chain stupidly tight there should be no problems, at all.

Sounds like my method works after all, and much, much simpler!

[jimgl3_imp]

you all are overlooking one thing... there is a green and red zones marked on your adjusters. if you have proper length chain and it's not old and stretched from excessive miles, if the adjusters are in the green zone, you're fine.

this from cb750, but shows my point

[Cormanus]

Thanks, Max. That’s really good information.

[max]

Thanks Max. So, just thinking out loud here (I’m clearly not going to do it). By Honda setting the limits as 1” to 1 1/4” in theory it only NEEDS to be 8mm (sorry for mixing measurements BTW) to allow sufficient slack in the drivetrain before it locks up.

In other words there is a decent safety margin built in here so unless you do your chain stupidly tight there should be no problems, at all.

Interesting points jfro, from what i remember during the test i have a feeling that the chain will run out of slack -before- it reaches it's tightest point if adjusted at 8 mm on the center stand, in other words the headroom ( difference between at rest on the center stand and tightest point ) is not a linear sum but changes with chain tension and angles.
From memory the difference was closer to 10 mm the first time i tried to do the same thing with the chain at 50 mm slack but it was not a very accurate test so i repeated it when i took the pictures.

You may actually want to try out your theory, do the same test and let us know, i like to know where the limit is and others may do too.

My way of thinking is that the lube inside the chain is motivated around the pins with every half revolution, seems to me that you don't want to evacuate the lube every time the chain rotates with too much tension but leave enough space for the lubricant to access this spot instead of creating a dry spot on the pressure point similar to glazing up of the cross hatching inside the cylinder wall which provides the oil film for the pistons,

Another thing is sprocket wear, not so much a problem with our bikes but i can imagine more wear on the front sprocket if the chain is too loose and started riding higher on the teeth wearing that part out sooner?

Certainly not an experienced mechanical engineer but i try to figure out the stuff i don't know by testing and observing the results combined with some reasoning, like Richard Feynman said; the first step of a theory is guess and then test your idea to see if it is correct.

[Tev62]

you all are overlooking one thing... there is a green and red zones marked on your adjusters. if you have proper length chain and it's not old and stretched from excessive miles, if the adjusters are in the green zone, you're fine.

this from cb750, but shows my point

That is the case but the thread is discussing the proper amount of slack rather than overall chain wear. Just because your adjuster is in the green zone it does not mean you have the correct amount of slack. This slack is to make sure there is not excessive force on the chain and gearbox output shaft. Many a home mechanic has screwed up their output shaft bearing with an overtightened chain.

[the Ferret]

Having followed the thread with interest i did some experiment yesterday but decided that i wanted to know the measurements, so today i adjusted the chain according to the manual with the pull/push method of " best standard " and here are the results, hope i'm not boring anyone;

the difference between pushing and not pushing down on the centerstand


Chain adjusted to 33 mm play on centerstand ( virtually similar to sidestand in my case )


The shocks are removed, it's easier to remove the right one with the wheel elevated;


The wheel is lifted 105 mm off the ground which is the tightest position of the chain
and the slack is reduced by 8 mm ( now 25mm )


lifting the wheel to remove the shocks;


Five pics limit reached, on to part two;
Rather than using a tape measure i have resorted to pushing the chain up to the chain guide and found a point that corresponded with the correct slack of the chain, all i have to do is push the chain up, look at which point it meets with the plastic guide and know if the slack is correct;
too far forward means too tight, too far back means too loose.
The red dot is when the slack is according to the manual but like Dave i like a bit less tension for a more relaxed chain so i use the place of the blue dot,that also gives me a bit of slack just in case i forget to find the tightest spot in the chain, thus far it's working.....


here is what this place on the chain guide looks like from a distance;


Each to their own, just thought i would share my findings here and hope someone else will share his findings as well, always wanting to learn something new that i had not thought about, cheers.

Excellent post Max. Thanks again for your dedicated work on behalf of the forum!

[dave]

My hat is off to Max, again! Thank you for performing this test and posting the results Max. I have a question though. In your third picture from the top the chain appeared to be pretty tight - there wasn't any droop of the chain on either the top or bottom. Measuring chain slack is a highly subjective process, and depends entirely on the mechanic. I would bet you can measure a half inch difference in chain slack depending on how much force you apply to the chain to deflect it during the measurement. What one person calls "acceptable" chain tension, another person may call "too tight". After I snapped the countershaft off on my CR500 I have been very careful to not over-tighten a chain. When I measure my chain slack I put very minimal force on the chain when deflecting it to obtain a measurement. If you can P.M. me your email address I would like to share with you the photos I took performing a similar chain slack test on my XR650L, and I am very interested to hear your comments. Thanks again Max.

[the Ferret]

so...if you do the PULL DOWN THEN PUSH UP method of checking slack and adjust to to say 1 1/8" of total slack using THAT method (between pin when pulled down and same pin when pushed up)

would you have MORE .... or less SLACK ... if adjusting it to 1 1/8" slack using only the PUSH UP method ? (between pin with chain at natural hang and same pin when pushed up)

There would be 8mm (3/10ths inch) of difference between the two right? (that's pretty negligible)

[max]

Correct, using the same measurement, let say 1 1/8" with push only you end up with more slack as a result ( looser chain ) than when the push/pull method is used measured with the pins as reference ( i think we snuck that in ).

[jimgl3_imp]

IF using stock length chain Tev62, I respectfully disagree. stock length chain, not worn out and overstretched, in the green zone, will be within spec.