Changing the Chain on a Honda CG125

I know, this is out of chronological order, but I had this saved as a draft and forgot about it.
Anyway, here you go.

So I've decided to change the chain on my motorcycle.  I had changed the cush bearings, and I was going to change the chain at the same time, but I discovered the existing chain requires a special tool to remove - one I didn't have.
I had purchased a chain and sprocket kit for the bike; it claimed to be the OEM for the CG 125, but I later had my suspicions.  I purchased the kit not knowing the first thing about motorcycle chains, other than the fact that they need maintenance and changing.  After installation, I did a bit of research on the chains and discovered that the bike comes from the factory with a 14 tooth front sprocket and a 44 tooth rear sprocket.  The kit I purchased contained a 15 tooth front sprocket, so this has the (negligible) effect of a higher top speed, and fewer revs at any given speed, ie if the bike was turning 4000rpm at 30mph, it was now turning at 3725rpm.  Not a big deal, but the end effect is I change gears later, and I haven't got as much power on tap at 30mph as I used to.  It's a tiny effect, but on a wee bike like mine, every little bit helps.
I was changing the chain on my bike for two reasons - one, as I said, it is a regular maintenance item, and I have no idea how long the chain had been installed; and second, there were some links that were siezed and were not giving me the smoothest of rides.
The process is fairly straightforward - you expose the chain, remove the tension, break one of the rivets, grease the new chain, clip it in place, and then adjust the tension.
To do the job, I used the following tools:

• an 8mm, 10mm, and 17mm socket with the appropriate ratchet (for removing the various chain covers)
• a few ratchet wrenches, 8mm and 10mm (also for removing the various chain covers)
• a 1/2 torque wrench (for tightening the axle bolt)
• an adjustable wrench for the axle nut (its I think 24mm, and I didn't have a wrench for it)
• a chain rivet breaking tool (about a tenner off ebay - worth the money for sure)

So here are the steps.
First I removed the chain guard covering the top of the chain.  One nut, one bolt, very easy to do.  I then took the front sprocket cover off - two bolts for this one.  Again, very easy to do.
I then loosened the axle bolt and nut, and pushed the wheel towards the motor - this removed the tension from the chain, making it hang low.  I did not adjust the alignment nuts on either side; with the tension off, they could move freely off of their seat on the swing arm.
I had a look at the chain, and found a link with some rivets that looked different from the others, and figured this was a good place to break the chain.
The chain breaking tool is fairly straightforward to use - basically its a bolt with a threaded bolt inside it - the outer bolt holds the chain in place, and the smaller bolt inside is screwed down to push the rivet out of the link.  Its easy to do; the most careful you need to be when removing a rivet is getting the alignment correct.  The tool helps make it easy.  Here you can see how the rivet breaker is in place.  I have a breaker bar on the smaller threaded bolt inside to help push the rivet out.

 It doesn't take a great deal of force, but you do have to push a bit.

Once the rivet is broken, the chain pretty much falls away.  Mine was a bit stiff so I had to wrestle it off a bit (woof woof).

Here are the sprockets, all chain-less.

 (Note how wonky the gear shift lever is - this is the result of it being bent back into place with a hammer after my first fall.)  The new sprocket is in place; this was done when I changed the cush bearings.

(And yes, I have removed the pillion passenger's foot pegs - they kept falling down out of the storage position.)  This image also shows the original rear sprocket.  I couldn't change it because the pins that sit in the cush bearings wouldn't come out.  I have to buy new pins for the new rear sprocket.

I then got the new chain out, and grease it up with the can of chain lube that came with the chain kit, it was a white lube which helped make it easy to see if I had missed any spots.

 

There is a separate link in the kit, which is attached with a small clip.  Pretty important, this piece.  I gave it a good soak in the white chain lube as well.

Next I pushed the wheel as far forward as I could, and tightened the axle nut to hold it in place.  This made the two sprockets sit as close together as possible, to help get the chain on.  

So I draped the chain in place on the rear sprocket, and pulled it to the front sprocket.  This is where I ran in to some difficulty - it wouldn't reach.  

It was off by only a tiny bit, so with a bit of coaxing and pulling and pushing, I got the link to push into place.  Taking careful note of the instructions, I slid the pin in place - its like a cotter pin, but flat and holds the link together.  

At this stage, I wasn't sure if I needed to mushroom the rivet.  I thought I had read in the instructions that I had to, but damned if I could find them.  I figured better safe than sorry, so I decided to mushroom them.

I added the pressing bit into the chain breaker.  It had a small ball bearing - like sphere of steel in it, which, when pressed into the face of the rivet, would squish the metal, flattening it.  (Hard to describe, but it basically makes the force of screwing the bolt tight compress the rivet, flattening it.)  I attached the tool very carefully - I remember reading that its imperative to get it lined up correctly or it will crush the pin in the wrong spot.  Satisfied it was square, I screwed the bit against the rivet.

In the below image, you can see at the bottom of it is the factory-flattened rivet.  At the top is an uncompressed rivet with the clip in place.  The tool is attached to the middle rivet, and is about to flatten, or mushroom it.

I then checked the tension on the chain, and found it to be quite loose on the sprockets.  I don't know how that worked, considering it was in the same place a minute ago and it was too tight to get together....

Anyway, I adjusted the tension the standard way - 2.5cm of play in the middle of the chain, tighten the axle nuts and make sure the wheel is aligned - easy to do on these bike with the marks on the swing arm to help you line up.

With that done, I started the bike and put it in gear, carefully watching the chain and the sprockets - keeping my fingers away.  All seemed to be going the right way, nothing was loose, and there appeared to be no binding in any of the links.  so, I took the bike out for a spin and again, the character of the bike had changed from an unpredictable bucking bronco to a smooth, easy to ride, forgiving little pony.  Definitely worth the effort.

After my short test drive, I lubed the chain up again (I imagine some of it was flung off when I was riding), and parked it, letting the lube soak in over night.

Job done.

~~~~~

As I mentioned, I wrote this a while ago.  I can now update the fact that the bike is now running very well - the combination of new cush bearings and a new chain has made the drivetrain feel much for solid an predictable - the transfer of power is as smooth as my clutch will allow, and old Hank seems much happier for it.