Topic: cb550F and cb550K parts differences

[paulages]

okay lloyd, this one is pretty much for you, but any help is appreciated.

i have three cb550K models, but one someone began trying to cafe, using some "F" parts. in the process, they changed the stock exhaust to the supposedly stock F 4 in 1 supersport header. i want to use this header for the bike i'm building, but on my mockup bike (the one dude already tore into), the header interferes with the brake pedal and kickstart, dragging on both of them. is there a problem with my header (in other words, is it not the stock 550F header he said it was), or does the cb550F have a different brake pedal and kickstart lever, which clear the header?

also, is the dust seal which sits low on the forks leaving most of the fork tubes exposed, rather than the crinkly kind on the earlier K models a 'pre vs. post 77-'78 difference, or is that a K vs. F thing as well?

[TwoTired]

The F models definately have a different right footpeg and brake arm to clear the 4 into 1 exhaust.  The kick start arm articulates differently as well, and the foot peg folds out of the way so the kickstart pedal arm can be used.
If you need them, I can take pics for you.

The front forks for the 77 CB550 F were slightly different design with just the little dust boot cuffs, exposing the upper fork tubes.  The 75 and 76 used the same forks as the K models with the accordian boots. The fork "ears" that mounted the headlight also accepted the accordians in a mount ring.  The 77 has different fork "ears" with no features for holding the accordian boots.  The 77 and 78 K models used the same fork arrangement as the 77 F model.  So, the fork boots are model year centric rather than F or K related.

Is that an understandable explanation?

[paulages]

yeah, thanks lloyd. i did some searching around on the honda microfiche, and found differing part numbers for these models, but was really looking for some practical info. i have most of the parts for the F which is the one being totally rebuilt, except for the pipes, though i have those on my mockup bike. however, the brake arm on the mockup bike is from the supersport, and rubs on the end of the header, even with the F brake arm 

i guess i'll cross that road when i actually get there, but i sure as hell don't want to go paying a bunch of money on ebay or at overinflated local used parts stores for something that still doesn't work. thanks.

[bryanj]

Unfotunately it aint just the kickstart and footrest different the frame is also different, not where the engine slots in but where every thing else mounts especially exhaust, rear footrests and seat. If you are cafing it and putting on rearsets ets you should be able to modify anything you need as its all non strenght critical

[TwoTired]

I've replaced the stock exhaust with OEM type on two Fs.  As I recall, the brake lever hit the exhaust, even when putting the same one back on the bike is came off of...

After eliminating the "something bent" possibility.  I put brand new crush gaskets on the header.  And, before actually crushing them, positioned the header outlet and muffler in the desired position first.  This achieved the clearances I needed and worked out well.  So, it is tight and proceedure specific even on an F frame.  But, as bryanj points out, the K and F frames are different.  I can't say for certain the F header will ever work right on the K frame.  But, if you are of a mind to, maybe new crush gasket may help?

I don't think the muffler hangers are in the same place between K and F frames.  Look to make an adaptation there if you are trying to use the stock muffler.

Cheers,

[paulages]

i'm certainly not stuck on using the stock F exhaust, but i do want to use a 4 in 1. you know how it goes...building a bike from a powder coat up, every little thing adds up, and though i don't want to cut corners where it will show, why go looking for a new header if i have one that will work?...if it will. i cut the rear brackets off of the frame before having it powdercoated, so rearsets and rear exhaust mount differences are pointless. i planned on a short silencer, just off of the header, and fabbed a mount to the frame right at the end of the header. i figured i will never have a passenger with a cafe seatpan, and i like the look of a stripped down frame.

lloyd, i will try the new crush gaskets when i get ready to install the pipes. if that doesn't work, i guess i'll just go aftermarket. i guess that's a whole other thread in and of itself, but any suggestions as far as that goes? MAC?

[paulages]

could someone provide me with a close picture of an F exhaust header where it goes under the brake arm and kickstart pedal? i'm pretty sure that my header is stock--and in good condition, but i want to make sure that it is sitting where it is supposed to before i go looking for a new brake arm. right now, as i said earlier in this thread, the brake arm rubs on the collector. i thought the arm i have came off of the F, but it doesn't seem so.

any detailed photos of this area would be greatly appreciated.

i have to note also, that i have not yet dropped the engine into the F frame, and am hoping that the afforementioned frame differences and new crush gaskets will fix said problem.

[tgascon]

I had the same problem with my '75 CB 550K when I tried to put on a header from a '75 CB 550F.
I got some advice from Matt Borden from this forum.(included)
My mecanic buddy wasn't too keen on it so Plan B.
We installed the header with the brake pedal off so it would seat properly. Then he cut my pedal into 3 pieces. He used the pieces and some steel stock and after a little welding I had a new brake pedal. The new pedal allows for full travel w/o striking the collector and we were able to retain the return spring and the brake switch.
I have a photo of the header w/o the pedal so you can see it. Also I incl a crude drawing of the pedal from an overview.
hope that helps!
Todd

[paulages]

thanks. i was thinking of having one of the blacksmiths i share my shop with help me heat and bend it as needed, but i'll surely wait until  i try it all in the F frame. my mockup bike was a K, but the real one is an F, so maybe it won't be a problem.

[TwoTired]

could someone provide me with a close picture of an F exhaust header where it goes under the brake arm and kickstart pedal?

Here's  One