On now to the flywheel. The brass casting was very tight and try as I might, I could not get it set up to give me the full dimensions shown in the drawing.
I faced the first side then drilled the hole for the crankshaft 9.8mm, used a small boring bar to straighten the hole and then ream for final sizing. I got a nasty shock when I went to use the reamer and found it went straight through! When I used the boring bar, I didn't take into account the cut on the backstroke while withdrawing the tool. Nothing for it but to enlarge the hole and fit a new piece in place and start again. The new piece was press fitted in place with the addition of the Loctite.
Before drilling, I machined the eccentric which is used to drive the water pump and in full size, the ignition system. This was done to ensure there was still some wall thickness of original metal round the new insert. When done, the flywheel was reversed in the chuck and drilled out to 9.7mm. Using the boring bar cutting a few thou at a time, I enlarged the hole checking when the 9.9mm drill would just start to enter. Now it was time for the reamer and after trying, the crankshaft was now a nice light push fit.
The flywheel is held in place with a 1/16" taper key. I have a Dore slotting attachment that mounts on the cross slide. The smallest insert bar I have has a 1/16" cutter, but when I tried it the tool would not enter the hole. Reluctantly I had to remove the flywheel and make up a new slotting tool. The Dore type would be very difficult to make in a smaller diameter bar, but fortunately Michael Cox came to my rescue. He had designed a unique keyway slotter to put keys in a modified pulley wheel he was working on. That would do just nicely, thank you Mike. http://mikesworkshop.weebly.com/smal...ting-tool.html
However, I didn't use his method of hammering the cutter through the hole! The clamp is to hold the heel of the cutter in place and also act as a length guide.
As an aside, for those who have not seen his site there are some quite good ideas that can be adapted for other machines.
Full size, the flywheel is fitted with a retractable starting handle. This is not shown on the drawings, but is easy enough to make. Using my centre finder, I lightly scribed a line that went through the keyway and this was carried over to the flange. The hole for the starting handle was drilled on this line at the half-way point on the flange. The handle itself was a piece of steel bar threaded at each end. On the inner end, a collar was attached and Loctited. The outboard side has a threaded brass button for the knob. A suitable light spring from the 'spring store' is the retracting mechanism.
The position of the holes should be rotated from that shown on the drawing and they were repositioned as far as I could without hitting the counterbalance weight. There are also an extra 2 small holes that should be drilled.
The pencil arrow was to remind me which way to offset the holes!
The Emerald Isle