What gives??

So I've been looking at the information for KZ650's on this site and I noticed that there is 3 different listings for horsepower ratings depending on different years and models. So what gives?? The cams are the same, the timing is the same, the torque ratings are the same. The only thing that is different is the RPM's that Max Horsepower is reached.

The reason I'm asking is because I have a 77 KZ650B motor completely torn down in my living room that I'm rebuilding to go into a 79 KZ650C chassis. I also have the engine from the 79 C model and I wanna know which is best to put in for the most horsepower. Neither have the plates on top of the cam covers with hoses coming out of them and I don't know for sure that the B engine came out of a B or that the C's engine is the original. Is there any way to tell??

Thanks for any input/answers/history you might have about this question.

OK, here are some specs I have from FSM, (although I can’t find the 1978 B2/C2): 1977 B1/C1 64HP; 1978 B2A 60HP; 1978 D1A 58HP; 1979 B3/C3 64HP (except German model = 67HP); 1979 D2 62HP; 1980 B4/C4 64HP; 1980 D3 62HP; 1980 E1 60HP; 1980 F1 (US Model) 62 HP. The 1978 B2A and D1A had smaller carbs (VM22SS vs. VM24SS on other models) I think the rest of the differences are due to exhaust systems (the crossover pipes cost a couple HP) and emission stuff. You could probably do a parts comparison on Kawasaki.com to see which models have which parts are common or different. To figure out which year each engine was made, take a look at the engine numbers and compare them to the chart at models.kz650.info/index.htm

According to the FSM and my own all original 650C2:

The 77 and 78 B1/B2 and C1/C2 all used the same engine with 64HP. The engine serial numbers look like this:
KZ650BEXXXXXX where the X's are the sequential serial numbers starting with 000001....or maybe 0000001.

The 78 B2A used a 60HP engine and the 78 D1A used a 58HP engine.
The D engine serials start with KZ650DE.....
I have NO idea how to tell a B2A engine from a standard B engine.

The 79 B3 and C3 used a 62HP engine. I have no idea what the number sequence starts at. This is where things will get murky for you since the engine number will PROBABLY
still have a B in it....so it'll be hard to tell these engines from the 77/78 engines unless you can find a starting number in the archives somewhere.
The 79 D2 used a 60HP engine and I'd ASSUME that the serial will STILL show a D in it....but that's just an assumption on my part.

The 80 B4 and C4 went back to the 64HP engine. Again, I have no idea what the engine serial numbers started at.
The 80 D3 used a 62HP engine and, again, I'd bet that the engine serial has a D in it somewhere.
The 80 E1 used a 60HP engine. No idea of engine serials.
The 80 F1 used a 64HP engine....PROBABLY from the B model so MIGHT have a B in the engine serial. Again I have no idea of the beginning number. The US version F1 used a 62HP engine for some reason.

Since the compression ratios show the same 9.5:1 value for all years listed above, I can only assume that different power outputs were made by carb jetting and exhaust setups/back pressures. I can't imagine that they'd bother making 3 or 4 different cam grinds just for a variation of 6HP over the various models....but that's just a guess.

Becker, I hope this has helped somewhat and not made things worse for you.

Very interesting on the 1979 B3/C3 HP ratings. One Kawasaki FSM (#99924-1001-03 Sept 2, 1980) says 64HP another Kawasaki FSM (#99924-1007-03 July 25, 1979) says 62HP. I wonder which is correct? Ed

I also understand the exhaust on each has something to do with this. The B/C models have different setups than the D models.

I am interested about the rest as well. I put carb bodies from a 79kz650 on my bike. Everything bolted up from the original carbs so I don't think I traded down, but interested to see.

if your building the 77 motor to go in a 79 bike, make sure to get the charging system worked out, the 77 has a different system than all the others, off hand I am not sure about the wireing or how to adapt it to work.
Steel may be the best to answer that one

For comprehensive Z650 info do an internet search for jarle Z650.

The 82/83 CSR models came stock w Mikuni BS32 carbs & have the highest listed horsepower. My 81 CSR has the Mikuni VM24s & has a lower hp. The only significant difference in the bikes of which I'm aware is the carburetors.

Very interesting on the 1979 B3/C3 HP ratings. One Kawasaki FSM (#99924-1001-03 Sept 2, 1980) says 64HP another Kawasaki FSM (#99924-1007-03 July 25, 1979) says 62HP. I wonder which is correct? Ed

WAG here but maybe the -1007- FSM (which I have) doesn't take into account the smog stuff on the US market engines.
They probably realized this and corrected it in the -1001-
FSM. My .02....

And on related matter: Why the heck would a later manual as per your post, Ed, have a lower part number ??? -1001- versus -1007-. Stuff like that makes no sense....at least to me.:side: :silly: :S

Ya, alot of this makes little to no sense to me. I'm guessing that the differences have to do with carbs, smog/emissions equipment, or exhaust. I'll be using a kerker, no emissions equipment, and what I think are VM24's but they don't have an acceloretor pump. how do you measure carb's??

As far as charging goes I'm using a batteryless/starterless wiring harness that I'm making custom so that won't be a problem. Thanks for all your help guys I appreciate all the information. I'll go home and get my engine number so I can figure out exactly where it comes from.

H2RICK "Why the heck would a later manual as per your post, Ed, have a lower part number ??? -1001- versus -1007-. Stuff like that makes no sense....at least to me."

I noticed that too, and it doesn't make sense to me either. I did a double-take when I saw them. The manuals are original and haven't been torn apart or re-bound, so I guess it's just Ma Kaw's way of keeping us puzzled. Ed

so I guess it's just Ma Kaw's way of keeping us puzzled.

Well, Ed, it worked that way for me.....:S :blink: :silly: :lol:

Ok so the number on my engine is KZBE064234. I tryied to put this into the serial number sheet I found on here but I'm not sure how to use it. Can anyone tell me what year and model this comes out of?? As far as the FSM goes I've seen part numbers that are supersceded by other newer part numbers that are only a few digits lower. Why?? I'm not sure but I think its because the major manufactures hate us. Not really sure what we ever did to piss them off though. Maybe it had something to do with how we chop up their finely engineered products to make them different. Who knows.