This is Ajay Fernandes.Ajay's primary job at Ushtara Engineering Pvt. Ltd., is to see that the company always has enough cash to continue its activities. Cash, after all, is to a business, what blood is to the human body. Too much is as bad as too little. Too fast is as bad as too slow. 
To perform his role well, Ajay has to be like a camel, storing up resources when times are good and releasing them when they are required. 
It is perhaps our common obsession with frugality and being prepared for downturns that led Ajay and I to name our company Ushtara. Ushtara or ऊष्ट्र, is the Sanskrit word for a camel. and if you look carefully at our logo,  



You can see the Camel nestling there, proud, observant, stoic.
Ajay can be reached at ajay@ushtara.com +91 98450 07177
Back to the engine story
In part 3 of the engine tale, I talked about the challenges we faced developing a good casting for the cylinder.
We had to modify the pattern, to a dump core box in order to avoid problems with flash and core shift.
The guys at Ashoka Bearing, closed the mold with adhesive at the mating surfaces;
packed green sand around it to resist the forces of the molten Alloy;
and poured the molten metal
our fingers were crossed so hard, they hurt a little

SUCCESS!!...well mostly
As we anticipated, the dump core box solved most of our problems. Here is the cylinder as it came out of the mold.
Here's out it looked after it was shot blasted and cleaned up
Once the runners, gates and risers were cut off, it started looking a lot like a cylinder
Although not perfect, (it still had a little bit of gas entrapment and shrinkage porosity) it was good enough to make a running engine from and prove in reality what we had hitherto only done on paper.

Piece of Cake
Now, we were back on familiar territory. Machining is what we do day in and day out, so no challenges there.
We had already prepared complete drawings for the cylinder
We started by creating a datum surface on the cylinder top face. This would act as a reference for all the other machining surfaces. We clamped the raw casting on the CNC vertical machining center and machined the datum.

We also rough bored the cylinder.

Then we put the cylinder upside down on the VMC and machined the lower deck. This is the surface that would be in contact with the crankcase. We also machined the spigot and mounting holes in  the same setup and machined the bore to finish size, with only 0.05mm stock for honing.

A small but important operation performed on all modern engine cylinder bores is Honing. Honing makes the bore very very round and cylindrical. This means that the piston will have an easier time going up and down.
As an additional benefit, honing leaves a cross hatch pattern on the bore, which retains lubrication oil, which reduces friction and increases the life of the cylinder and piston rings.
Because we don't have a honing machine, we got the honing done  at an engine rebuilding shop in Yeswantpur, called Akbar Lathe Works.
WARNING!!! Turn down your volume
We assembled the cylinder on to the crankcase.
A few hearty kicks and the engine burst into sputtering life!!

We're going to take a slight break from the mechanicals and develop the magneto and electronics for the ignition system.
More on that in the next part...