montyjohn

42 minutes ago, ChrisNewport said:

You assemble the piston to the crank, slide the piston into the cylinder and sit the brearings and seals in their places, run a like of Dirko over the sealing face of the cylinder and then put the base pan on, Hold it all together and fit it into the housing then put in the screws and tighten in a cross corners pattern

Perfect, thanks for the clarification

39 minutes ago, ChrisNewport said:

Whats it say inside the piston? 

Not all that much.

Pictures below are all of the new one.

Inside it just has a "37"

The old piston has a "22" and nothing else.

Batch numbers maybe?

11 hours ago, Macpherson said:

Perhaps neither is genuine, what year is the saw ? 

The saw is about 10, maybe 12 years old, and was bought new by my farther in law.

Had very light occasional use until he put neat fuel in it. Free saw for me....

It's had no work done to it, the the old piston is definitely a genuine stihl one.

I've just bought a new cylinder and piston off eBay.

The eBay title read "Genuine Stihl Cylinder With Piston 40mm 023" and I'm wondering if I've fallen for a sneaky trick, where the cylinder is genuine but the piston isn't.

I'm not familiar with genuine Stihl parts so I was hoping somebody here would know eitherway form the pictures below.

My old piston has P15D written on the top, whilst the new one says T15C. Anybody know what these mean?

The arrow and writing on top of the old piston is a bit neater.

Some of the lettering on the side are a bit different also.

The final thing is the piston rings on the new one are black, whilst the old ones look silver. Is this normal?

Is the above anything to worry about?

If not, then I'll ask the seller to confirm it's genuine and take his word for it, otherwise, if there's anything that's an obvious issue, I'd like to know beforehand.

Final point which I hadn't anticipated.

The screws for the bottom casing appear to be self tapping, and there is no thread in the cylinder. Is this expected on a genuine cylinder?

And does anyone know how they would assemble?

Would you use the screws on the cylinder before assembling to cut the threads to make final assembly easier?

Would you seal it on the bench with some spacers (screws would be too long otherwise), take the screws out after the sealant has set, then carefully fit in the chainsaw.

Or just fit the screws for the first time in the chainsaw with sealant and put some muscle into it, it'll be fine?

Many thanks

Original Piston

New Piston

Side by side