I installed a new DID 420 106 link xring chain on my 1990 a week or so ago. I've been running the chain on the looser side because if I set it according to the manual it looks too tight. I have it set on 3 with the adjusters and it's quite loose on the stand and upright but feels okay when riding (I can tell its a bit loose).

If I set the adjusters one click tighter and it's at the correct slack according to the manual, the chain seems way too tight when upright. Off the kickstand there is maybe a half inch of total deflection, and that's without a rider on it. Is that correct? Or should I just leave it loose?

The way I check mine is to sit on it and check the chain with my heel.

Maximum tightness happens when the swing arm is horizontal.

It took me quite a while to get used to how loose the right adjustment is.

I always err on the side of loose if I am between two clicks on the adjusters. Being too tight puts the output shaft bearing under extra stress.

You get wear on the sprockets and chain to with to tight chain, 3cm is perfect. You can actually hear on the sound when riding if to tight, but it doesnt take very long time before its not tight if you do some hard riding. I had to cut of one link on the chain.

You need more slack than the manual suggests, thats for sure.

I dont agree, manual says 3-4cm. Cant see any reason running the bike with more.

Yeb, manual states something like that, unloaded.

Try to set the slack for that, unmount the rear shock, and move the swingarm up so the frot sprocketshaft, swingarm pivot, and rear axle is even (pretty much horizontal as I recall, where the chain is tightest) and the chain will be too tight. Or get the fat kid from the block to sit on the rear fender for a cheeseburger

Most streetbikes have 30-40mm chainslack spec'd. Our bikes have suspension with more travel. My brothers ninja250 should have between 35mm-45mm.

I'd say 40mm should be minimum on ours.

Remember that chain dont have same slack al over, look for differences before adjust. Normal riding onroad and over 4cm slack will give you bad acceleration.

I think you need to explain the part about acceleration for me, guess im stupid, cause that makes absolutely no sense for me. If you want more acceleration, use a non o-ring chain like the mx's do, but it wont last long, and will quickly rob you horsepower instead.

The bike needs the same chainslack onroad vs offroad, unless you use a shock with less travel onroad.

Going over speedbumps, riding with luggage/passengers ect will move the swingarm so the chain is too tight, if you adjust it at lets say 30-35mm.

Just try to see for ya' self, much easier than "arguing" over the internet.

Have a nice day.

Yea offcourse the accelation is the same when chain have to tightn up before the bikes moves contra bike moves straight away..Who is talking about a bike with two people and alot of luggage? Normal ride onw person 3-4cm is perfect, if you like running bike with chain slack its ok for me. For me the bikes feel just real bad with slack when you give throttle and when you drop throttle, wheelies even worse. But you know best Jens i quess..

Best way to get a feel for it is to do as above - remove the rear shock, put everything else back - wheel, chain etc - put the bike on a stand, then block the back wheel up until the wheel spindle, swingarm pivot and centre of front sprocket are in line. Now, adjust the chain so its just tight at this point - dont forget to spin the chain a bit to find any tight spots.
Refit the shock, and make a note of how tight the chain is at this time - this is how tight you want it, so you can always reset it to this point in the future.
Its a bit of a faff, but you only have to do it once - once you have the benchmark, you can always reset it. The same results can be achieved by putting a ratchet strap over the seat and round the swing arm, and pulling it down til the 3 points are in line, but I prefer to do it the other way.

This technique works on every bike.

You can put a rachet strap on the swingarm then sit on the bike and attach the strap to the frame and snug it up to get it sagged down for adjustment. I don't measure but usual my chain is just starting to lift off the front of the swingarm at the point. Probably 2inches slack

I believe you are referring to this type of article, more or less:-
Chain Adjustment + Wheel Alignment | Horizons Unlimited

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Dave

Hi, my point was, eventho' I probably didnt explain it too well, you need the same chainslack regarding how and where you drive, doesnt matter if you ride with or without passengers, luggage ect.

Its cool we do different stuff and all, I would just like to avoid others to ride with a chain thats too tight. Others might use their bike for actual dualsport use, where the suspension works more, and the chain will be in a tight position more often. Hope thats makes sences, its hard for me to explain in English.

Im really impressed by the fact that you can feel the difference between 40mm and 45mm slack when you ride. But lets be grownups and not argue over a couple of milimeters.

I would still suggest you to check the chainslack by removing the shock, or use straps as suggested otherwise. Im sure you will be surprised, I was. Its a good excuse to lube up the suspension-links ect.

I really dont hope I make the impression that im a know-it-all, not my intention. I do, however, hope I know a lot about what works for me and my bike. My bike is raised in the rear, and I need even more chainslack than stock. I still got 28.000km out of my last chain, with a lot of offroad-duty, so it cant be too bad.

Hi there, just a clarification. You need to have some slack when the chain is at the tightest position, thats the whole point of setting the chainslack.

Happy riding to all of ya'

Hi just my thoughts last time I tightened my chain to recommended specification tightened everything up then sat on bike and chain was very tight. Ended up re setting it so was more slack, I think trial and error works and see what works for you. How much you weigh etc. I am with Jens on this one more slack is better.

Bingo. This is the right way to do it. It's also the method employed by responsible O.E.M.'s. Keyword "responsible". I find most recommendations for chain slack in factory service manuals are off by a country mile.

I would add to the above that once your "zero" (minimum chain slack) has been established, back your adjusters off by one notch and record the slack. That will be your MAXIMUM permissible slack. Then you'll have both the true min. AND max. permissible range. No more guesswork.