Big Piston - little piston ?


XS650 Member
Reaction score
Somerset UK
Is there more than type of piston used on the XS650 ?

I'm rebuilding a very tired XS650 lump. I bought a pair of +1.00mm pistons and had the tired old barrels re bored to fit. Imagine how VPO I felt when, having fitted the barrels, I wound the crank round to TDC and the top rings popped out and said hello!



The new pistons seem to be approx 10mm taller. Any ideas what it wrong? Are the pistons simply wrong or did they change the pistons at some point?
You've got con rods and pistons mixed up from the 447 series and the 533 series of engines. 447 con rod is 130 mm from centre to centre. 533 con rod is 140 mm from centre to centre. 533 pistons have the gudgeon pin 10 mm higher on the piston.

Looks like you have 533 rods and 447 pistons.
You have 447 pistons, on 533 Euro rods, sold a pair last year, clearly had what they were in the ad and had the buyer ring me up with the same problem.

you'll have to find somewhere in europe to buy pistons Heiden will sell them, or try wemoto or yambits.

Where abouts in Somerset are you?
OMG - what a can of worms :( I had no idea that the engines had so many different rods. The advert on e-bay, with a Japanese company I've bought lots of Kawasaki bits from before, said '74-'76 1.00mm oversize and I thought what a result. I didn't see any mention of this issue in the workshop manual. This would be annoying if it were my bike,but as it's someone elses, it's hyper embarrassing.:banghead:

I live in a little village, Pensford, just south of Bristol, Jay. Whereabouts are you from?

Thanks for all the help lads!
Many thanks Bob.

That is the company I bought the pistons from. They seems very good. I shall send them an e-mail asking if they can supply the correct pistons for the engine I'm working on. I'm guessing the 553 reference is the beginning of the part number?

Many thanks

533 is the number on the side of the rods.

I'm in Brent knoll, bit farther south of Bristol
Hi Jay

I whizzed past Brent Knoll day before yesterday when I was out on my Rex wasting fuel for the shear joy of it :)

Have a great new year :)