I have a wiseco piston I'm going to be replacing, as per my meltdown. Alas, I do not have calipers nor access to them (Buying parts instead of tools), so I'm not sure exactly what size the piston is. The piston in question is a Wiseco 533 P2. On the piston crown it is stamped .50 mm. Anyone know what the diameter of it is from that info?

Thanks

The piston is a 533P2 (533M08050)are you sure is says .50 ?Is this a pilot jug or 350 jug?

It is an ody piston. That is the old number and you need to remember that it is in metric not english. The new number is 533m08050 for that piston. That piston is slightly heavier than the new ones. The part number on the new pistons tell the size, the 533m08050 (or533p2) is a 80.50mm bore which is .50mm over standard bore of 80.00mm. That is if it has been bored before. If you have a postrecall Engine and it has never been touched than more than likly it is a 78.50mm bore. Confused yet? Here is some more, the old Wiseco pistons are fine but the instructions are slightly wrong. If I remember right they call for a .003 inch cylinder wall clearance. Well it is too tight for these hot running machines, It needs to be around .005 inch clearance. The clearance will need to be matched to the piston because every piston is not exactly the same. The ports will need to be beveled and bridge touched up. If I were you I would send to Randy@odyssysalvage.com or tripple E. Or if you have a good machinest that has done
two strokes and knows what he is doin(not many do!!!!) That is why I caution you, and you will be doing the process over again in only a couple of hours after rebuild.

Thanks for the help guys. It is for a 350, and has been slightly bored because of a previous rebuild, but alas, he didn't relieve the exhaust bridge or drill the cooling holes, so it didn't last long at all. The piston fits within the specs according to my handy dandy feeler gauge, so I just needed to know the piston size so I could order the same one.

Thanks Again!

Good deal, with a little prep work and hone you will probably ok. What is just as important as anything is beveling the ports, so the oil doesn't get scraped off after each stroke. Just a FYI.

Sorry got confused on the numbers there-you can also go to Wisecos page as well www.Wiseco.com they have all the numbers for you.Denis Kirk http://denniskirk.com sells the piston sets really cheap as does Randy at odysseysalvage and also theres a seller on ebay sledpartsguy that sell them as well.

You need to measure each piston and find its largest outside diameter you can not
go by what is stamped on the crown of the piston that is one of the problem with
the wisecos their finish size varies quite a bit.

Hillside was selling the FL350 Wiseco Piston kit for $81.38 call them to ensure
current pricing. 707-263-9000

cwwiedmaier your saying the new wiseco tech sheet says to use .005 on the
350? Last sheet I seen (probably 1.5 years old) said .004

Brooks 350 piston that I installed had a spec of .005 along with my polaris in the briggs had a spec of .005. Like Hoser said be sure to set you clearance to the actual dimension of the piston and not what is stamped on the piston and box.

The last one I installed had a .005 inch spec.