A bit of a back to basics story here. I thought I had this covered sometime back, but I actually don't, my bad. A couple of weeks ago, a geezer asked if I thought the chain on his Ninja 300 was worn out. Wish I'd taken some pics of it now to give you a better idea.
The chain was hanging down in a large arc because it needed adjusting so badly. On closer inspection, it was also really greasy/dirty where chain lube had been sprayed on constantly during its life, but had never been cleaned. It was also heavy and slow to move because of the grease.
Now you can give all the advice you want in person, but words are meaningless unless you're doing the job with them, there and then. And if the person isn't confident in adjusting it correctly, it's a tough call. Everything is easy when you know how.
Regarding the wear factor? It was half-and-half. Yes, you could pull the chain links away from the rear sprocket slightly (a good test for a worn chain), but then I've seen far worse. If it was mine, I'd give it a damn good clean up first, spray it with chain lube again, adjust it and take it for a ride. And then monitor it for a while.
So, a good time for a tutorial. Take from it what you will, ignore it completely, or find out how I get years from chains and sprockets.
Here's a Can-Am 175 that is just beyond a simple clean and adjust. I'll admit defeat with this one.
Chain tension is important.
Before we get into the nitty gritty, there are several reasons why a chain has to be at the correct tension, and are pretty much as follows:
Too tight, is two bits. (An old lecturer of mine used to love that saying.)
1) If a chain is too tight, it puts incredible stress on the main shaft bearings in the gearbox. This will wear them prematurely, and could cost a lot of money to fix.
The chain and sprockets will also wear prematurely, and run very hot due to friction. This isn't so much of an issue, but who likes wasting money?
2) Another reason you don't want it too tight is for the suspension to work correctly. Yes, it can actually stop you using up the full travel on your suspension when you might need it most. Why?
Because as the suspension compresses, the swingarm starts to level out from its slightly downward facing position. When that happens, the distance between the gearbox sprocket and the rear sprocket increases, tightening your chain. If you don't believe me, get someone to sit on your bike and watch it.
If it's adjusted without any weight on the bike (as in a person), it could go way too tight when you hit a large bump, or carry a passenger, and your suspension travel is then limited.
That might not sound dangerous in normal riding, but if you were cranked over, and that tyre wasn't able to maintain contact with the road because the rear shock was compromised, you could lose the rear end.
Too loose, and you lose. (Yeah, that was shit!)
1) When a chain is too loose, there is a huge risk of it being displaced, or falling off, and the consequences of this could be dire.
A chain that is flailing around underneath the bike could hit you, get wrapped around the front sprocket and break the engine cases, or possibly even cause the rear wheel to lock up. Not good.
Suspension comes into this scenario as well. As you're now well aware, when a swingarm starts to level out, it tightens the chain. But obviously, this works in reverse too.
If you suddenly go to fully-extended rear travel, like when going over the crest of a hill without throttle pinned, the chain becomes slack as the suspension unloads momentarily.
Whatever scenario, if it's that loose, there is no good news. Some get away without breaking anything. Personally I hope I never have to find out.
2) Gear changes also become sloppy, and smooth riding is impossible. Why? Because every time you let off the throttle and decelerate, the slack in the chain has to be taken up on the lower run of the chain.
If this is confusing, think about how the chain is working. When accelerating, the tightest point is above the swingarm because the gearbox sprocket is pulling the chain in the direction the rear wheel is turning.
It will remain tight until the throttle is released, where the rear wheel is now having the effect of slowing the engine. The slackest point is now above the swingarm, but the transition between both states causes jerky riding.
What is the correct tension?
As a rule of thumb, 25mm - 35mm, or 1" - 1.5", in the centre point of the chain run, but I also like to check it when there is someone sat on the bike too.
To be accurate, on most bikes there will be a handy sticker telling you the exact measurements the manufacturer requires. Use that, or the handbook, to stay safe.
Also check the chain in a few different positions, and I don't mean lying down, kneeling and then standing. Roll the bike forwards a foot at a time and recheck the tension because there will be tight spots, even on a new chain and sprocket set.
But before we go into adjusting, let's get the chain clean, work out if there are any tight/seized links etc. If it looks good after that, we can look at getting the tension right.
Cleaning your chain.
No matter what way you look at it, if you don't do this regularly, it's going to be a messy job. What will you need?
1) WD-40, or similar.
2) A toothbrush.
3) A paddock stand, or centre stand.
4) Plenty of old rags to place under the chain, and to wipe it clean and dry.
Once the wheel is in the air and able to be turned freely, I spin the back wheel while spraying the chain with WD spray. Once it's covered the whole chain, out comes the toothbrush.
I'm using the CBR for the pics, though the chain was already pretty clean. Not ideal, but I don't have anything else to work with while I do this.
I always scrub both sides of the chain, the top and bottom run, and make sure the O-rings and rollers are visible and clean. If it's really caked in grease, you might do this several times. When they're that bad, you can also expect a big buildup of grease under the front sprocket cover too. Take it off, clean and inspect if you're confident.
Use old rags to clean off the residue, and start again if it's still covered in crap. Do the rear sprocket too. Once the chain looks good again, dry it with more rag and check for tight spots in the chain (turn the rear wheel a bit at a time and check chain tension each time).
Also look for links that don't return to their original position, or line up with the others. They are slightly seized/binding, and you probably can't do much with these to fix it.
If you look at the third link down from my fingers, you'll see one slightly out of line with the others. That's a binding link. It's not horrendous, and I won't be replacing the chain anytime soon — it may even free up, but gives you an idea of how it starts.
This is from a lack of maintenance, and all too common with secondhand bikes.
Obviously, before and after pics are a bit useless here. I've dried it off with a rag and cleaned everything else around. Watch where you put your fingers when doing this, and hold the chain as it moves away from the sprocket, not as it wraps around it.
So the chain is now clean and dry, it's time to spray on some grease. There's loads of spray greases available now, and for years I always favoured the PJ1 blue. At this present time, I'm using whatever's on my shelf. I'm sure most of the sprays in your local bike shop will suffice nowadays. Honda still specify 80/90 gear oil, but that's messy!
Spin the wheel backwards and spray the top of the lower chain run as it goes away from you (under the swingarm). You want the spray to wet the O-rings, and also find its way into the rollers between the inner side plates.
Keeping the O-rings clean and lubricated is what makes these chains last years. If the O-rings dry out, dirt will get past them and thats what ruins the chain.
Once the grease is applied, I get the WD back out and use it to clean off all the overspray on sprocket carrier, rear wheel, swingarm and fairing. Dirt will stick to it otherwise. Am I OCD?
Adjusting your chain.
There are two parts to this:
1) Tension — how much slack or freeplay you have in the chain.
2) Alignment — ensuring the rear wheel, and hopefully chain, is inline with the rest of the bike.
So, in the poor quality pic below, you can see wheel spindle (axle), the adjusting bolt and locknut, and the markings on the swingarm for alignment.
The idea is to loosen the spindle nut, undo the locknuts and adjust the bolts equally, maintaining the same position on both sides.
Always give the tyre a whack from behind to maintain contact between axle and bolts while adjusting. If the manual states 35mm, without anyone on the bike, grab the chain and move it from lowest to highest point and measure. Hopefully you can estimate this without using a ruler, but do whatever makes you happy. Nip up the locknuts and recheck, it will change slightly due to play in the threads, so always recheck.
Now turn the wheel and check in several places. You'll have to pick a happy medium on a worn chain, there is no perfect spot. Even with new components, you'll find problems with imperfect sprockets which will cause tight spots. It will never be absolutely perfect, just make sure the tightest spot isn't too tight.
Once you're satisfied that there are no excessive tight or loose spots, re-tension the spindle nut. Now check the chain again, seriously. Some swingarms have a tendency to alter when that bolt is tight, and will effect the tension.
Is this becoming a ball-ache yet?
When you're used to it, it all becomes second nature. The only reason I continue to check is because I've seen it happen so often.
The alignment marks lie.
You didn't want to hear that did you? For day-to-day commuting, it will never matter. I've used them for years, but now double check with two straight edges down the length of the bike. For a race bike, it'll be checked with a tool that slots into the swingarm pivot bolt and rear wheel spindle. This is adjustable but, once set, you can match both sides of the bike. I want one!
There are chain alignment tools available, but not recommended because they can leave your wheels out of true. Any intolerance (which is pretty typical) in the sprocket carrier, or bearing, and your wheels won't be inline.
For alignment purposes, the chain is secondary. You are looking for a motorcycle that has its wheels perfectly inline. The chain will follow suit. It doesn't work the other way round.
Again, the way to prove this is to grab the rear sprocket and try to rock it in and out, from top to bottom. I almost guarantee there will be very slight play in the sprocket carrier bearing, which is perfectly ok, but that is why you can't use the chain alignment tool for accuracy.
Get your wheels inline, the chain will follow.
Hopefully this will give some insight into getting the most from your chain and sprockets, and have a bike that handles nicely.
So now you have a clean, lubricated and correctly-adjusted chain, you need to go for a blast and see how it feels. And when you get back, you get to check it all over again.
Safe riding folks, any questions, please ask.
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