I have a n 42 engine and it has been at the machine shop what a nightmare the guy told me that it was a std 260 so i ordered pistons and guess what too small. so i asked him whats going on he said your 260 had a 280 engine in it ugh. well he said get std 280 pistons so i did and gues what too small the engine had been bored .20 so i am trying to find these pistons mean while i have the other 2 sets and con not return since i bought them on line . any one have an idea cheap since i had already spent 500 dollars in pistons and rings that don't fit