I have found several sources with various information. The reason I started to interest me about these numbers is because I have a B2, apparently, that only have the automatic cam chain adjuster, the front forks and the front brake caliper that are B2 spec, the rest are all B1. It's frame number is KZ650B501933 and the engine number is KZ650BE017961.
Here are the numbers from one source:
Model Year Engine no. Frame no. Color
KZ650 B1 1977 KZ650BE000001 - 007860 KZ650B-000001 - 500001 Candy Emerald Green, Candy Super Red
KZ650 B1* 1977 KZ650BE000101 - 045147 KZ650B000101 - 026990 Candy Emerald Green, Candy Super Red
KZ650B1* 1977 KZ650BE000101 - 043949 KZ650B500001 - 508015 Candy Emerald Green, Candy Super Red
KZ650 B2 1978 KZ650BE-046001 - 027501 KZ650B027501 Luminous Dark Blue, Luminous Burnt Red
KZ650 B2* 1978 KZ650BE508016 - 515325 KZ650B027501- 032200 Luminous Dark Blue, Luminous Burnt Red
KZ650 B2/A 1978 KZ650BE046873- /L KZ6500508016- /L Luminous Dark Blue, Luminous Burnt Red
KZ650 B2/A* 1978 KZ650BE061299 - 090685 /L KZ650B033551 - 044828 /L Luminous Dark Blue, Luminous Burnt Red
KZ650 B2/A* 1978 KZ650BE061299 - 092000 /L KZ650B515326 - 523523 /L Luminous Dark Blue, Luminous Burnt Red
KZ650 B3* 1979 KZ650BE092001 KZ650B046201- Candy Emerald Green, Candy Persimmon Red
KZ650B4(E)* 1980 KZ650BE092001 KZ650B523524
Based on the numbers you may have a 1977 KZ650-B1. Here are some things unique to the 1977 models; if your bike is configured this way it is probably a B1 since it is doubtful someone would have changed all these items:
B1 has round front brake master cylinder – B2 has trapezoid shaped MC:
Attachment 1977FrontMC.jpg not found
B1 has front brake caliper in front of fork – B2 has caliper behind fork
Attachment B1Caliper.jpg not found
B1 has 3-phase excited field generator – this will have the 3 allen screws circled in red – B2 does not have those screws
B1 has manual 3-position petcock shown in picture – B2 has vacuum operated petcock
Attachment petcock.JPG not found
Also, it is my understanding that the B1 has no hazard button on the left handlebar control switch – B2 has hazard button. Sorry, I have no picture of the switch. Ed
I created the last table you posted, did so from several different locations - data sets. In no way do I claim it is 100% correct. Rather, it is what sense I could make from the info I could find. I will say the numbers for the B models came from Kawasaki micro fiche sheets so I am pretty confident in them. However, I do not know that we will ever really know the frame and engine # info unless Kawasaki releases it, and up to now they have not done so.
The frame and engine #s you posted do appear to make the bike a 77 B1 built in the US. Keep in mind that it is over 30 years old and unless you are the original owner, you have no way of knowing what may of been changed over the years on the bike. It could also be that at some point in the production run of the B1 some items intended for the B2 were installed due to lack of B1 parts. I do not have any info to back up this thought, but I would not doubt it possible.
Thank you both for the responses. It makes sense that it is a B1 - somebody on this forum led me to think it was a B2 some time back, but that's irrelelvant.
I believe the bike in question is a hybrid I've read about somewhere at some point, a mix of B1 and B2. It has the brake caliper behind the leg, but the round master. The fork legs like your C1, Ed, as is the charging system. No hazard switch. Manual petcock. Solid front peg mounts. Plain swing arm bearings. Capital KAWASAKI letters on the cases. But an automatic cam chain adjuster.
Yes, I know the pictured ones are different from your actual ones - as are the ones on my parts bike; caliper behind leg, rubber grommets on top like yours. Only difference I'm aware of is that the top key for the spring retainer is square on the B2 and hex on your bike.