Topic: 500 vs 550

[nick_ander]

I am getting the picture that these two bikes are almost identical. I would guess the jugs, pistons, rings, and heads might be a little different. Is there anything else that is different. I am building a 550 but I'm looking to expand my parts options so I need a little rundown of what will work and what won't.

[Tim.]

What year 550 are you building.  The major difference aside from the obviously greater displacement is the transmission - 550 was better than the 500.

Aside from that, most other parts would be interchangeable, with the exception of the exhaust I think.  The early 550's looked just like the 500's, but later 550's all took on the 550F SuperSport look and I think there were some frame differences - mostly in the back end under the seat (sidecovers and their mounts for example changed along with seat and tank).

Front ends, suspension, gauges, carbs, wheels, fenders etc. should all swap.  Air cleaners probably not - the 550 (at least later models) was different from the 500's.

I've owned both a 1973 500 and a 1976 550 SuperSport, and those are the differences I can think of.

[TwoTired]

It is far more complicated in the details than you think.  Even 550's have parts that don't interchange between year models.  Of course, there are also many that do as well.
All 550/500 engines do swap in all the frames.  Carbs have internal difference between years.
500s have trans and clutch based on 350 twin parts.  The 550 has its own improved design.  Yes, the barrels and top end are different, but the cam is the same. Etc, etc.

There are so many differences, in fact, for both engine and frames that I don't believe there is a complete rundown of truly interchangeable parts between models.  It is handled on a case-by-case basis. Or, adaptations are made to cross dress the models in a hybrid fashion.

If you have specifics, I can try to help.

Cheers,

[nick_ander]

I have a 76 550. I am only refering to the case to top of the head covers. Im most interested in things like case covers, clutch covers, kickers and shifters, gaskets, cam, valves, ect. Anything match up with any other bikes as far as motors go? I think I read on here that a 750 carb swaps.

[TwoTired]

Because the 500 clutch is different from the 550, so is the clutch cover.
The clutch adjuster for the 500 in on the sprocket cover, so these are different, too.
Points cover - is same for both
Alternator covers will interchange but later model 550s look slightly different.  I think the 76 is the same as the 500, though.
Shifters - same for both
Kicker - same for both unless you have an F model, those are different.
cam - same for both
Valves/springs - same for both.
Cam covers are the same 500-550 through mid production year of 76. After that, they were improved to negate excessive cam cover wear (which cam also ruin the cam).  You can swap the later stuff onto earlier motors as entire sub assemblies.

750 carbs are not a direct swap to the 550. Possibly adaptable.  But, I thought the carb spacing was different along with inlet/outlet diameters.  So, carb couplers would be a challenge.  I remember a post where someone used early 650 pumper carbs on a 550 and reported good results.  Both 750 and 650 carbs had larger venturi size than the 550's 22mm.  However, unless you are caming up or porting the head, or expect to spin the motor way past stock redline, I'm not sure larger carbs are going to realize much bolt on benefit.  Certainly jetting issues will have to be dealt with.

Cheers,

[florence]

Is there much difference in performance between the two?

[bryanj]

Nope

[SteveD CB500F]

Tell it as it is Bryan!

[TwoTired]

It depends on the value of "much" doesn't it?

I'll take the 550 in a drag race. 

[SteveD CB500F]

Like you Lloyd, I've owned various versions of both.

Drag race - down to the better clutch no doubt!

[bryanj]

OK when you get to 17 stone (238lb) There aint no difference!!!

[turboguzzi]

I think it depends what CB500 you are comparing too.

in europe at least there was a K3 version of the 500 which had all the transmission improvements of the 550. i.e. shift forks on a separate spindle and gearbox oil pump.

TG

[TwoTired]

OK when you get to 17 stone (238lb) There aint no difference!!!

Reminds me of the old drag racer's credo.  "There's no substitite for cubic stones"...
Or, something like that.

Cheers,