Monday, March 24, 2014

Fitting the cylinder block; for real this time.

More progress. I started by borrowing Witold's circlip pliers and some Versachem Mega Grey.

As I mentioned, the rings compressor band I have is near-useless, so I did it oldschool and used my fingernails to feed the rings into the grooves one by one, as I lowered the piston into the bore.

Time to fit the first "inner" circlip.

The other "inner" circlip, on piston 2, goes in before I fit the piston into the bore, or there'd be no room to do it otherwise. Piston 2 goes into its bore, again just using my fingernails. At this point I'm thinking of how I can repurpose that ring compressor as a toilet roll holder.

Ok, both pistons are a good fit, they rotate freely and the rings are all where they're supposed to be.
Now for the fun part: using whatever I had around the garage, I propped up the cylinder block just long enough to line up the conrods and insert the wrist pins. Total time? 2 seconds for each side.

Honestly, I don't know why you'd go to the trouble of doing it the other way 'round, installing the pistons, rings and circlips on the conrods and then trying to fit the whole cylinder block over them. That's just nuts. Instead, the way I (and countless others, of course) did it, means that you can keep a close eye on each single ring, take your time and avoid any sort of stress (mechanical or otherwise) for a much neater fit.
Then, the "outer" circlips and that's it, the block is ready to be lowered down.

This particular cylinder block is to be fitted without the conventional paper gasket. You could use a copper base plate if you wanted to, especially to lower compression, but in this case the aforementioned Mega Grey should be all that's needed. Whilst omitting a gasket here may seem unorthodox, I have seen it done successfully in the past, specifically on our Moto Morini 500. Provided the surfaces are true, and that the sealant is applied correctly, there shouldn't be any leaks. Unfortunately there is only one way to know for sure, so... watch this space.

I used one of my trusty luggage straps to hold the cylinder in place while the sealant set, then I went about bolting everything down. Here's an inconvenient truth: because of the shape of the flange, fins and some of the fasteners, I don't think you can use a torque wrench here.
Perhaps some exotic type of tool exists (an extended 12-point crow foot insert?) that allows you to do that, but I don't have it. Instead, what I did was to follow the tightening sequence and go around it a few times (a lot of times to be honest) progressively and as carefully as I could.

I could see the excess sealant gradually being squeezed out, and I reckon I was careful with the quantities I used around the oil return hole, as well as all the way around the inner edge of the mating flange. Again, only one way to find out if I've done a good job or if I've really messed up.
So, right now the cylinder block is snugged down, I don't think I've forgotten anything (cam followers, locating plates, bolts, "safety"wire, pistons, wrist pins, circlips... what am I missing?) and I even managed to put the pistons in the right way around!

Trust me, getting them mixed up is easier than you might think...
If all of the above is correct, I'm one step closer to putting the motorcycle back on the road. Incidentally, I've carefully tried the kickstart and everything is rotating freely.

All of this really didn't take long, which goes to show that if I had time (and all the parts ready) I could have had this all done in just a few days, a week tops, including all the other touch-ups and small fixes I have on my list. Anyway, even doing a little bit at a time is enjoyable, so I can't complain.
Next up will be getting the cylinder head ready to fit, and we'll also have a stab at annealing a copper gasket, oooh!


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