Topic: CB550 or CB650?

[Doggie]

I want to build a Cafe Racer and I have a 1975 CB550K and a 1981
CB650C. I'm looking for help on deciding which one would be better to start from? Also which carbs would work better?  ( the '81 on the '75??)                           Thanks, Doug

[MoMo]

You will find parts readily available for both.  Why not post photos of both so we can get a better idea as to what you have to start with?  If the 550 is stock and in good condition, I'd restore it and cafe the other...Larry

[Doggie]

Right now both are in a shed covered by 12" of snow. The 550 is stock and the 650 was stock but I took it apart last fall and boxed it up.
                                                          Doug

[Stev-o]

550......just sayin'

[Pinhead]

The 550s are much more commonly Cafe'd (and are more common in general) because of the relatively "flat" stance of the bike while the '81+ 650s are more commonly chopped/bobbed due to their already "stretched" stance (more rake/trail and a taller/more angled tank from the factory).

The CB650 has a better and more powerful engine though it doesn't have a kick starter (the purists often argue that you can't have a true Cafe bike without a kick starter).

The stock CB650 will make more power than most moderately built CB550s due to a better piston and head design and better ports from the factory. Though if you're rebuilding the engine for power the CB550 has more aftermarket parts. Forum member Soos (CB650 guru) has almost negated that problem, however, with his piston machining projects.

Trying to decide which carbs are "better" will open a can of worms. But Soos has archived various carb options for our CB's (including some Suzuki carbs if I recall correctly). With different carb rubbers, CB750 carbs can be used on the '81+ CB650. I'm not sure about the CB550, though.

I may be a bit "behind" on the aftermarket options of the CB550 so don't take my info as gospel; I have a '79 CB650 so most of my knowledge is of the 650s.

[Bluegreen]

Put the 650 motor into the 550 frame. Find non CV carbs. Problem solved.

[Hush]

Got a sneaky feeling the 650 is a taller motor!

[Kong]

I had two 550s to chose from, in fact still do in a sense because one bike is being built and the other is my parts bike.  I have titles for both of them so that didn't enter into the decision.  One was modified a good bit, and poorly, the other had been modified a little bit and the work was well done.  On was running - barely - and the other was not.

I chose the older of the two bikes (a '77 and a '78) for two reasons.  First because its frame had less rust on it and second and most importantly because it had a tight swing arm.  Probably something to do with the bike's low milage.

I would imagine any number of things could influence your decision on which one to use but you're the only one with the bikes in front of you and know where you want to end up.

[Doggie]

Thanks Guys, Looks like from the feedback that I got on here, that I will be going with the 550. It ran when I got it, drove it around the backyard a little bit, then it quit, and started to leak fuel out of the overflows.
     Right now I am working on a CB650C which I linked up with a Jr. Dragster frame. I brought the bike in for the winter so I could move the front disc and calipers to the rear wheel. Also moving the speedometer housing that was on the front wheel to the rear wheel. Changed the rear spocket from a 39t to a 43 t. Mounted the master cylinder under the battery. All that is left is lengthening the speedometer and tach cables, lengthening the throttle and clutch cables, hooking up cables to the m/c and making linkages to the shifter. That will be done in the spring when I can find the frame in the snow!!!

[thehammer]

ya, i would not recommend dismantling the rack of a set of cv carbs, or working on them at all for that matter. solely because of the vacuum Ts that run from carbs 1-2-airbox and 3-4-airbox. such a chore to assemble. also the way the linkages are put together in the middle just boggles my puny mind.

[wardenerd]

I have a 77 550F and an 81 650C.  I would think the 550 would be a better candidate than the 650 because of how they look stock.  The 650 is considerably more powerful than the 550 but I would think the nimbleness of the 550 again make it a better candidate.

[Doggie]

Seems like all the folks here agree that the 550 would be the best way to go for a Cafe Racer. Looking forward to starting it after I finish the dragbike. Watching the new show on TV and getting the mag has made
me more determined to get going....
                                                              Doug

[FunJimmy]

Put my vote on the 550 too, and not just because I cafe'd a 550.

Cheers
FJ