Kitchs 1200 Coupe - road legal!

[Kitch]

umm, so i pulled the sump of the Reg Cook A15 tonight
its got 77mm pistons, with only 1.5mm dishes, so would be quite High compression I imagine in the vicinity of 11.5:1

Bad news, I pulled the cracked #4 piston out, to find it had also lost one of the skirts on one side,
good news I found complete skirt in bottom of sump
bad news it had a friend
worse news, neither of the two skirts matched the #4 piston

nett result, 3 of the 4 pistons are broken!

Makes me wonder if there is something seriously wrong with the piston selection or original set up when engine was built.

The motor has only done minor work since being built (perhaps 10 or 12 club events).

so much for tracking down a single piston to suit and getting out of jail for cheap


Cracked piston


hmmm, spare skirts........

[Bartman]

How manny mm dia are the gudgeon pins? got any more pics? They almost look like cast E5 pistons to me.

[Kitch]

think you could be right Bart.
YCP - 40412 pistons, 19mm gudgeons.

Might have to get oversized ones and rebore, but I am interested to work out how/why the skirts broke off in the first place.....

[nick_m]

over revving i'm guessing?
Thats a lot of damage though!

[nick_m]

Bart is probably most qualified to answer actually. He's blown up more motors than anyone I know!! haha

[Bartman]

okay, 19mm gudgeons are the factory size. The E5 ones use 20mm pins.
You could use E5 pistons, or I'm told it's all the rage atm to use MX5 pistons. Both use the larger pin, but you could them use ca16 rods, which are mad stronger than the A seires ones.
Can you please post more pictures of the pistons and rods you have there?

[Kitch]

I will post some pics up in the next day or two.

I searched online with the model # but didnt come up with anything to tell me what they are.

[Kitch]

The penny drops...
I was reading the number backwards because of the way it was stamped

Actually they are 21404 (not 40412) model
which are standard A14(S) type, mine are 40 thou over size, so are 77mm

why use A14 pistons in an A15?.... unless they are a bitr longer, and they machined a couple of mm off the crown to increase CR?

http://www.ycpiston.com.tw/p1-5.html" onclick="window.open(this.href);return false;

Appears YCP's have some special T6 heat coating treatment to them

[Bartman]

HPC coatings in Aucks can do a thermal barrier coating on the crowns of pistons.

[Kitch]

Not much to report of late - been flat out at work, so havent got much done

I have done a couple of wee things like machine up spacer bushes etc for the front struts, acquire a replacement front hub, and Jacob has made me some sweet-as mount bars, to enable me to mount the coupe up to the rottisseire

Rainy day today so Will helped me strip, clean and reassemble the throttle body internals.
They are heaps cleaner, and operate a lot more smoothly: