petcock woes

[kcsteve]

I recently bought a 1982 750 custom for my son-in-law that is in need of some tlc. Among other things, the petcock leaks. I ordered a petcock that was supposed to fit an 82 but it wasn't close. I ordered a factory Honda replacement using the VIN and it wasn't close either. It was considerably larger ( and High dollar ). I am thinking the tank may be off an F model or a pre 82 and uses a different petcock. The bung on the tank measures just slightly under 18mm. The ID on the threaded nut on the old petcock measures just slightly over 17mm. The ID thread on the factory replacement measures 20mm.
I would appreciate any advice on what to do. I really don't want to end up with a toolbox full of $130.00 petcocks.
Thanks again, Steve

 

[dirtdigger]

Send pictures of tank and petcocks

 

[kcsteve]

I haven't been able to get any photos yet. I took the bike to a local shop to get the carbs rebuilt and haven't got it back yet.
I'm finding quite a few Honda petcocks for the older bikes that are 18mm. Would there be such a thing as the wrong 18mm petcock?
Thanks, Steve

 

[dirtdigger]

They used several different styles of petcocks throughout the years.