Miyata 110 3-butted CroMo frame
I was lucky and found a Miyata 110 bike from the garbage two weeks ago. The bike is generally in good shape and I'm having fun in analysing the bike and seeing how to drop the weight of the bike. I came across questions about the frame quality, the year mode and the original component set. A label on the frame says that the frame is made of 3-butted CroMo (see photo below). Before I put the bike into pieces I assumed the frame weights around 1.8 kg (4lbs) as the 3-butted CroMo road bike frames usually do but the weight of the frame turned out to be 2.4 kg (5.3 lbs). I weighted the frame without the fork or any single component attached. The frame size is 56 cm (22 inch).
Question 1: Did Miyata manufacture different quality 3-butted frames for different models or are even the high-end models having such a heavy frame? If the answer is yes, are only part of the frame tubes 3-butted CroMo or what makes the weight difference?
Question 2: What is the year model of the bike? The serial number on the bottom bracket is PA47970.
Question 3: The components that were attached on the bike at the time I found it are listed below. Is the component set original or has somebody already upgraded some components?
Fork: Miyata Magnalight
Rear Derailleur: Shimano Lightaction RD-L523
Front Derailleur: Shimano FD-Z204
Brakes: Shimano BR-Z57 43-57
Pedals: SR P-468
Chainwheels: SR 307 (52 teeth), SR 362 (42 teeth)
Brake Levers: Shimano BL-Z325
Gear Shifter: Shimano L422
Seat Post: SR Laprade
Saddle: Wheeler Viscount 2288
Cranks: SR Signature 170
Bottom Bracket Spindle: NFS, Boron 86-1, model 3K
Handlebar: Winpista, Kusuki
Rims: Araya 700C
Hubs: Sansin 5345
Tires: Kenda, 32-66, 700x32C