I intended to change the crank of SR 400 to 500.However, when I decomposed it and measured it, the cylinder had spread a lot.So I bore up 1 mm and put a piston of WISECO.
It is 511cc specifications at compression ratio 10.

I didn’t bore up for a long time.
And I previously did in a manual milling machine.
So, I am boring on NC lathes for the first time.
First, boring is shave down from the top.And release blade at the underneath.
And, when the blade returns, it is necessary to prevent the blade from hitting the workpiece.So I have to use an instruction called G76’s Fine Bowling.

G76 Z-152. R1. Q.05
In this way, I did input to an NC lathe.

I tried to dig, but the length of the boring head was not enough because the SR’s cylinder was big.So I bought the thing plus the patch and lengthened a bowling head.

And I dug it.
In bowling it is a good way to finish it 5/1000 ~ 3/1000 mm small and then set it to the prescribed dimensions by honing.

This time it was 511 cc, but I would like to try to know how much CC can be done if I have free time.

The design of the dry clutch was completed a long time ago.However, it became clear later that a lot of jig for machining was necessary.
I am making it.
I plan to exhibit at the American Car Festa this weekend, but it may not be in time.
First I made a jig to hollow out the clutch cover.However, as the tip of the drill could not be cut off, the pilot hole of the M6 tap had gone wide.And the screw thread did not function.
Such a thing is the first time.

I bought helical coil wire screw thread insert in Benizen and made modifications.

Helical coil wire screw thread insert is this.

It cuts a tap with the same pitch but a large diameter and it is a thing put in a coil there.
It is used when revive a failed screw thread or when stand screws on plastic.
It took quite a while.

Even at the professional ironwork, if dust enters the drill polishing machine and it gets polishes with eccentricity, it seems that such troubles may occur.
Until now I was indifferent, but I understood that it is important to manage the eccentricity of the drill tip.
I get lost as to whether to buy a polishing machine.

Also, when I was examining SR, I discovered two things that I was surprised.
The SR has 500 and 400, but the parts are almost common.
SR400 is currently being produced, but the production of the SR 500 is over.
The SR400 and SR 500 have the same cylinder diameter.
So, it becomes 500 if I assemble 500 crank to 400.
400 and 500 pistons are slightly different, and a head is higher in 400.
So if you assemble 500 cranks on 400 pistons you can make a high compression engine 500.It seems to be very fast.
When I check a price of the genuine crank of SR500, by several percent seem to rise year by year.It was a whopping 90090 yen.
Because the crank of 400 is about 40000 yen, it is considerably high.
The stroke up crank of the external goods is higher and it is about 140,000 yen.
This is the first discovery.
The second discovery is that it is cheaper to buy a 38 φ of the CR special than to overhaul a genuine CV carburettor.
Because it costs 20,000-30,000 yen when I overhaul a pure carburetor, so you can pay 30,000 yen and buy a CR.
And I assemble 500 pistons in SR400 of FI and may be interesting even if I make low compression and attach a supercharger.