Chainsaw Repair

He is no longer here and I know nothing about his links. http://chainsawrepair.createaforum.com/ported-saws/converting-a-husqvarna-261-to-a-262xp-with-modifiacations/msg32434/#msg32434

But only difference IMO is a dished piston was used in a 261. Put a flat top 262 piston in it.

The 261 I think used 2 shoe clutch and the 262 used a 3 shoe clutch. 

That is the only differences I know.

Now if leaving stock porting a 262 1990 K&S with the bigger 87 carb was the best. The others with mahle cylinder etc later on didnt have the same good stock porting and used a smaller 120 144 carb and I would guess thats is what the 261 used too.

Hope that helps.  Because I tried his link and it is no longer working like you noticed.