There's a well of information on the Net, and some of it is even good! Don't get me wrong, I'm not saying I know the exact words the abbreviations stand for, but I can tell you what they mean (learned it working for a Honda motorcycle dealer on Oahu). But, please don't take my word for it either, go down to your local Honda dealer & check it out. There is a data/VIN plate either on the frame at the side of the bike or on the frame neck/steering head area. It'll say "Model" & have the number. Ok, so here goes:

There are exceptions that I don't know because of model changes since I've been "in the business", but they basically follow the following formula:

First is the Alpha Digits which identify the engine configuration & type, such as CB, GL, VF, VT etc. If the bike's engine is built to race specs, it gets a further designator "R". CB= Inline-four engine
VF= V-four engine
VT=V-twin engine
GL= Opposed Cylinder Engine


Second is the engine size (self explainatory).

Next digit is the one which identifies the type/body style of bike. Most sportbikes are an "F", most cruiser bikes are a "C"

Last, if the model has a sub-model it'll have further alpha digits after. For example the Magna was a VF750C. They also offered some with a mini-fairing around the headlight & two-toned paint. This one was a VF750CDC. On our beloved CBR's, the last digit also tells us which generation bike it is. The original (Hurricane) was the CBR600F, the next generation is the CBR600F2, followed (of course) by the F3/F4 and F4I (Injected). I have no idea what the "RR" actually denotes...anybody?

Hopefully you will all see the pattern here. Here's some examples of different models by model name & engine type followed by the Model Designator:

Nighthawk 750 (inline 4)= CB750
CBR (inline 4)= We all know these!
599/919 (inline 4)=I haven't looked yet to see what model designator they got.
Interceptor (V-4)=VFR800I (Remember the "old" VFR750F?)
Magna (V-4)=VF750C
Shadow 600 (V-twin)=VT600C
Shadow 750's (V-twin)=VT750C (with additional designators for different 750cc
models)
Shadow 1100 (V-twin)=VT1100C or CDC (many different models have been made
in current years & they all ended with a
different designator number, but they all
started with "VF1100C"
Goldwings (opposed cylinder)=GL1800?


Honda is the only manufacturer I have a clue about since they're the only ones I've worked for. Hope this helps someone, somewhere understand what all those digits/numbers mean