Length of the pistons pin for 66cc motors?

My 48cc engine has too much play between the connecting rod, the piston pin and the bearing. I don't like clattering engines.

I thought about what to do. Correcting the small end of the rod? Not so easy. Getting a bearing with larger needles in it? They would laugh at me.

Making new piston pins, that is the easiest way for me. BTW I let them make.

Next Monday they shall be hardenend and tempered. The length of my 48cc I can measure (33 + 0,1 mm). But my 66cc, which I imported directly, still didn't arrive. How long will the pins of this engine propably be? Can they differ from one manufacturer to the other?

Thank you for your help.

Multipaul

Could someone please be so kind to measure how long the piston pin of a 66cc engine is? Naturally somebody who has such a pin laying around.

Multipaul

I had measured too much play between piston pin and the small end of the connecting rod (4/100 mm). At first I had thought about 8/100. I had forgotten to divide by 2.
I contacted Fa. Bückner who make piston pins for Stihl and other well known companies.
Mr. Brückner told me the price for only one piston pin and I sat down. But we found a possibility to get it cheap. He gave me a couple of end pieces from his production, which they can't use. It is original Stihl material.



I had to cut it just the right amount. I decided to choose 40.2 mm for any 66cc engines in the future. This work is done.



On Monday they will harden and temper my pins at Brückner. But only the surface, not through the material.

The last step is to grind the pin to the appropriate diameter (in case of my 48 cc it is 10,02 + 0,005 mm). That will do a friend of mine. In his company there is a external cylindrical grinding machine and he's the owner.

So I'm lucky. The piston pins cost two pounds of coffee and some driving.

Multipaul

Hallo Mannhous51,

Thank you for looking. I really didn't know that there are different diameters. 10mm and nothing else, I thought. Now I know that I was wrong.

The piston pins will match at least in my 48cc HT engine. Whether the longer pins will match in the expected 66cc? That's by chance.

Where I'm living, there are no spare parts. I have to make the engine long lasting and durable. Everything less than 15.000 miles lifetime is nothing. Finally this are 50hp/1000cc engines.

Multipaul

Hallo Toadmund,

you didn't tell me the length. Is it shorter than 40,2mm?

Just as your caliper flexes, I'm assuming that this piston pin has a diameter of 11,0mm.
Thank you for the pictures.

All bearings for substitution must have the same diameter of the rollers. Logical.

Multipaul