Engine rebuild Update

Had an interesting discussion with a guy from Pro-bolt about torquing his bolts down, and they say they don't recommend anything over 16NM for these bolts, so needing 24NM was too much for it. For the moment I have replaced
with the originals - at least I know they will torque down, even if they disturb the airflow a little.

Finished the rest of the engine over the weekend, When I wanted to install the pistons, the machining on the inside was not quite at the right angle for the gudgeon pins to go through, on 3 out of 4 pistons....So I had the choice to try and correct it myself or send the pistons back to Laurent losing 4-6 days in the roundtrip in the post. After a chat with Laurent, I decided I would try and file them, although after a quick try it was impossible to do manually, so I decided to try and do one in the mill. The difficulty with milling is always getting the workpiece held firmly, and with a piston being round this was difficult, not wanting to mark the exterior of the piston, yet hold it firmly enough so it doesn't move.

Anyway, using very light cuts, I was successful at taking some metal off the inside, and eventually getting a free fit on the con-rod. I did the other 2 in the same way, although I made a bodge of Nr. 2 as I cut too deeply and then had to move the cutting tool out so there is a ridge on that one - I hope it won't matter!

The RG is special in that it uses thrust washers to space out the con-rod on the cranshaft in order that it doesn't touch the crank webs, however the washers are in the small end, so the alignment cylinder, piston, conrod, crankshaft is all linked. So me taking adhoc material off the pistons could affect everything - we will see!

Due to Laurent taking material off the head to cut out the impact damage, I had to check the squish values of the front cylinder, The volume of each combustion chamber is 14.2ccs (measured by Laurent), anyway he gave me the tip of assembling the cylinders with the piston rings removed to that it would be quick to get them on and off, which is what I did.

As you will remember, the technique is to position 3-4cms of 2mm diameter solder around the pistons "stuck" on with grease, then you have to assemble the heads (I just tightened them not torqued), then you turn the engine over slowly and the solder is crushed by the contact with the cylinder heads.

You then measure the pieces of solder and that gives you the squish value of each cylinder.

You can take the average values by adding the opposing numbers and then dividing by 2. The front squish was just over 1mm and the rear was about 0.9mm, In order to change the squish you need to vary the thickness of the base gaskets, which I will need to purchase, as I don't have the correct size. The optimal squish is 0.8 mms for a 125cc cylinder, so the rear is correct but the front could do with lowering slightly. Having a greater squish will lower optimal performance, but is safer for eventual piston, head contact.... so I am on the safe side.

I have now installed the piston rings and cylinders, heads all torqued up nicely, and now I have to attack my rotary disks!