CB250 rebuild part 8

**16/3/2019**

If you've been following this then you're most probably wondering what I did about the alternator because I haven't mentioned it yet. Fact is I thought I'd be clever and that hopefully it wouldn't need to come off, I really hoped the cam chain would slip past the middle bearing carrier thing on the crank and I could slip on a new one while leaving most of the left case in situ. This didn't work out.

There is no room around the carrier and the stud for the nut at the top of it is always going to be in the way. This was a bit of a downer. So now I had to wrestle with the flywheel bolt and taper while the crank can freely rotate because I can't use a penny in the primary gears to stop it.. First remove the alternator cover:

The chain is driven by the start motor (yuck), here is the sprocket that sits on the end of the motor:

Refitting this to the motor would have been impossible with the alternator cover in place anyway so this all turned out to be not so much of a loss as I thought. So, oil filter chain wrench doodad:

Special clacker at the ready again..

 

Turn the chain wrench thing around so you can tighten and start with the special flywheel puller tool (bolt).

You might need a little extra help to stop the crank turning. These pistons are dead anyway because I'll be buying new barrels and probably pistons so I had no qualms about this.

After what seemed like sheer brutality (tighten the bolt, hammer, tighten, hammer, tighten, hammer) there was success!

Everything should be easy now. I don't know why the steel plate spacer thing is so rusty though.

The rollers for the starter clutch promptly fell out, except for one which was stuck in place. These will no doubt be a very good game of fun-ness to put back. Also red rust!

Thankfully the flywheel is magnetic so can serve its true purpose of a way to not lose things.

Since I apparently have to remove the crank from the case to fit a new cam chain I had to remove the other piston so that the con rod would fit between the studs. I didn't lose any circlips this time!

Another look at the carrier. Them bob weights are massive ain't they? I actually had to use the clacker to undo the bolts around it, using a normal wrench proved too difficult because I couldn't get the case to stay still.

Remove the bolts (and one nut for some reason) and let Thor do his work..

Thor actually causes me a problem later on from this, it turns out the middle bearing can move around in the carrier and this moves it so that the old chain won't come off. That takes me a while to figure out. Anyway, store the crank somewhere clean. If you can.

And admire the now emptier crank case!

There is a main bearing, a seal and some kind of gasket behind that plate. I don't want to see them if I can help it.

**9/4/2019**

I really wanted to replace the cam chain because "people in the know" know that the chain will be super slack by the time 93K is up. Here's how my original chain (bottom) compares to a brand new chain (top):

Hardly worth bothering with. Perhaps it's the 2000 mile oil changes I religiously do, or perhaps it's because the motor is so mild that the cam merely caresses the valves but this doesn't seem in dire need of replacement to me. Anyway, the trouble I had with the bearing carrier - it was because the stud that the tensioner sits on didn't seem to be far enough away from the crank weight:

But it turned out the carrier with the stud on it actually quite freely moves side to side and must've been dislodged by Thor. Oh how I laughed.