Sprocket and chain size

[Billiam08]

Hey guys so basically I've got a mini bike frame which I'm doing up and everything's going well but I'm having trouble working out the size of the sprocket on the rear wheel it's a 50 tooth but I need to figure out the pitch and what not for getting a clutch it looks bigger than 35 chain so any help would be appreciated it's on an old deckson mini bike and I can't find a whole lot on working it out ,cheers

 

[capguncowboy]

Measure from pin to pin to figure out the pitch, then measure the inner width to confirm the size (if there is more than one with the same pitch).

 

[Billiam08]

Okay I measured my sprocket with calipers and the thickness is .184 and I don't see that number on the chart above so I'm feeling a bit lost