little bits of rubber under rear fender area.

[b_rubenstein]

...I compress the swingarm with a rachet strap so that its pivot center is perfectly in line with both sprocket centers and judge my chain slack there where the chain will be at its tightest...

This is the appropriate starting point for establishing chain tension. The bike would then be placed on the side and/or center stand and measure the chain slack. Rider, or load weight is irrelevant, because it ignores dynamic suspension compression while transversing large bumps or dips.

What winds up in manuals may, or may not, be what engineers determined. There's a long chain of translations, tech-pub writes and proof readers that exists in creating manuals.

 

[DCTFAN]

If the bike was riding on a highway, a 150 lb rider will probably be around 1/2" if not more higher on the swing arm angle as they don't have the weight to compress the non adjustable shock. The chain slack will be different than a 250 lb rider who will have compressed the shock that extra 1/2" plus. Yes the shock will be moving up and down, but for optimal chain wear you would want the chain slack set to the position of the swing arm where most of the riding will be done.

From Mark. "99.9% of current motorcycles shipped to the US are sprung for riders that are 165 - 185 lbs. The sag is set for that and the manuals chain tension is set to that. So if you are ANYTHING from 100 - 165 or 185 - 300 lbs you would do yourself a big service checking the chain tension while sitting on the bike."

OR... and here's the big OR... get a rear shock or spring that is tuned to your weight putting the bike back to it's "Factory Sag" THEN, you could use the manuals settings and be in the ball park.

We were just talking about this as I was adjusting my chain and I'm a 210 - 220 lb guy (depending on beer season) and the stock chain tension setting was not right for me at all.
Mark was the head Tech at Cleveland/Arkon Honda when it was here and he was the head Superbike mechanic at The Ferrari/Ducati Of Austin. I trust him over any manual.

So, exactly how many mm difference does Mark's method produce vs the recommended slack?
I understand his logic, but is there a real difference to an average rider?

 

[DCTFAN]

Hi All,

I recently cleaned my chain and inspected the wear of the chain, sprocket and other areas. I then adjusted the chain tension and put it all back together. since then Ive noticed a heavy vibration when riding . Its very uncomfortable at highway speeds for longer rides. I took a look at the chain thinking it was maybe to tight and if anything it seems loose. I also noticed little bits of rubber splattered on the fender area. I think its from the chain wear guard as it seems to be cutting into it just a little. I just wanted to check and see if there could be rubbing from somewhere else before I assume its just that. Also would a loose chain cause this constant vibration? It was loose before I adjusted it with no issues and I adjusted it tighter even though now it seems loose again. Could it have been too tight and then caused it to stretch? There is not major wear on the chain or sprocket everything looks good.

How many miles on your chain?
I found when the chain nears the end of its duty cycle, it will stretch and strech and stre-e-etch.
I'd clean the stuff, put on new chain and check if it appears again.
End of story.

As far as adjustments, there seems to be two camps of thought.
Greenboy's method is generally more accepted in the dirtbike realm. (full suspension travel 90% of the time)
SleepyC method is new to me, but seems to be working in the racing realm (minimal suspension travel most of the time)
Adjust according to your own style of riding; but know the basic principle and understand why the manual recommends you do it that way.
It all makes sense. Everybody is right, yet to some they are all wrong.
Got it! I think.

 

[Deleted member 5383]

This is the appropriate starting point for establishing chain tension. The bike would then be placed on the side and/or center stand and measure the chain slack. Rider, or load weight is irrelevant, because it ignores dynamic suspension compression while transversing large bumps or dips.

Yep. It's the bottom line for chain adjustment. The larger the potential suspension travel is, the more change there is in chain slack from a fully unloaded or fully compressed suspension to when it reaches the place where the three center points line up. You want chain slack to be proper for THIS situation. One of probably many articles (with illustrations) on the subject:

how-to-properly-adjust-your-drive-chain

 

[SleepyC]

So, exactly how many mm difference does Mark's method produce vs the recommended slack?
I understand his logic, but is there a real difference to an average rider?

Good question, and I'm not sure. But my bike with only 2600+ miles on it had a slightly loose chain for my fat butt.

Also, as pointed out in that article, too loose to too tight might be a 1/4 turn of the adjuster, so I'm sure it's not crazy off, but I just can't ignore the weight difference, and I don't plan on removing shocks etc to test chain tension.
As always what ever works for you!

 

[Deleted member 5383]

Greenboy's method is generally more accepted in the dirtbike realm. (full suspension travel 90% of the time)
SleepyC method is new to me, but seems to be working in the racing realm (minimal suspension travel most of the time)
Adjust according to your own style of riding; but know the basic principle and understand why the manual recommends you do it that way.
It all makes sense. Everybody is right, yet to some they are all wrong.
Got it! I think.

there's little point to adjusting a chain for partial suspension travel and then hoping you never use more of it -- it's like moving your front fender way up and hoping it never hits the radiator, or positioning your bars so that they can easily hit the windscreen well before the steering has reached its full sweep ; }

 

[DCTFAN]

You adjust the suspension to the load, not the chain to the load, to attain correct free and race sag. I'm sure Honda engineers did the math/geometry correctly to arrive at the specs in the manual. Free sag would be about 10mm (plus/minus 5mm) as this is not a true off-road bike; on the side stand the free sag is less (mine is actually 0mm). Then adjust chain per manual.

"... mine is actually 0mm..."

0mm, hmmm, Sir Isaac Newton says, "no".

My understanding is this:

The chain slack adjustment is a static setting, where all relevant parts are fixed length
The suspension adjustment is a dynamic setting where most relevant parts are always changing.
Also, the two have no relation to each other, meaning they are adjusted independently.

 

[DCTFAN]

Let's look at relevant chain adjustment numbers for the NC models:

DRIVE CHAIN SLACK:
X/XA/XD:
30-40 mm (1.2-1.6 in)
SA:
25- 35 mm (1.0-1.4 in)

Two different slack requirements, but the range is the same 10mm.
Assuming a 1/4 turn of the adjuster bolt will throw the slack adjustment off;
a quarter turn is only +/- 0.3125 mm (a 1.25 pitch bolt will move 1.25mm in one turn)
What are we supposed to do?

What is with the generous range of adjustment in the manual?

 

[Deleted member 5383]

Article I linked cites 1% to 3% of the distance between sprocket centers when the swingarm center lines up. Most motorcycle manuals probably come up with figures that approximate this when the bike is set up to factory sag and with factory sprockets and linkage.

 

[fleetingyouth]

Ok so here is a pic of the chain wear guard. its only a little wear which wasnt there before the chain adjustment so I assumed that was were it was coming from.

Lets assume the little bits are normal. thats fine. The vibration is really what has me concerned.

I just had my bike inspected and the mechanic said the chain seemed fine. I looked, there arent any kinks or missing o-rings at least.
I set the chain tension based on the manual. I weigh about 180lbs. I loaded up the bike for the weekend trip maybe another 75lbs. The vibration is equally bad with and with out the gear loaded.

It wasnt a problem before the adjustment.
I'll try re-adjusting the chain based on some of the info given here.

 

[mtiberio]

might be an optical illusion, but that chain looks wore out. remember to adjust at the tightest point.

 

[rippin209]

Yeah it could just be the picture but I'm with mtiberio that chain looks done. The first time I had a chain that was worn out I thought I had engine problems it was so bad, it ended up being I had 4 or 5 tight spots so the chain had no chance of going around smoothly. If your getting to the point of spending money trying to fix your vibration problem I would recommend starting with a new chain

 

[670cc]

There is no way I could tell if the chain was worn or not, solely from that picture. I'd have to see the wear indicator on the swingarm, inspect the orings, inspect for tight links, etc. However it was stated that mechanic said the chain seemed fine.

I suggest adjusting it on the far loose end of the spec at its tightest spot and take a ride. I think more often than not, chains are adjusted too tight. I'm going to mess with a chain every 2000-2500 miles or so, so it's going to fall within a wide range of tension during that time. If I had to mess with it more often than that, I'd go get a shaft drive bike.

 

[Deleted member 5383]

Dunno about the NC, but on WR250R it's important to check the bottom of the chain slider (guys have actually eaten into the aluminum swingarm) so I check the bottom on the NC and not just the top, in spite of running front sprockets of larger diameter.

 

[showkey]

I vote we change the chain tension to chain slack............maybe that would help


Photo in post 32 ....assuming that red stuff is NOT rust. Red dust ?

 

[VE258]

imo vibration comes when chain is too tight. i've been there, on NC in particular. most likely too tight and misaligned

$10 digital caliper from HF to rescue!!!

Search results for: 'digital caliper'

 

[rippin209]

imo vibration comes when chain is too tight. i've been there, on NC in particular. most likely too tight and misaligned

$10 digital caliper from HF to rescue!!!

Search results for: 'digital caliper'

Overly tight or loose could have similar effects. When loose the chain does a wavy slappy thing that'll cause vibration also. How do you use a caliper to check chain tension or alignment?

 

[Deleted member 1183]

might be an optical illusion, but that chain looks wore out. remember to adjust at the tightest point.

I tend to agree. It certainly is way too dry and badly in need of lubrication.

 

[b_rubenstein]

My understanding is this:

The chain slack adjustment is a static setting, where all relevant parts are fixed length

It's a static setting for a dynamic system. The distance between the counter shaft CL and wheel axle CL changes when the bike moves. The static chain slack setting has to account for maximum possible CL to CL distance, otherwise components of the motorcycle may be damaged.

 

[DCTFAN]

It's a static setting for a dynamic system. The distance between the counter shaft CL and wheel axle CL changes when the bike moves. The static chain slack setting has to account for maximum possible CL to CL distance, otherwise components of the motorcycle may be damaged.

Agree, bad choice of the word "dynamic", although I am that sort of guy

My point was that given one specific motorcycle, no matter who rides it,
the chain slack setting has no dependent variable other than the fixed length of the parts involved.