CB550f V CB550K3

[Trigger]

Some time ago i asked on whether a CB550F tank was any different to a CB550K3. I had many replies and the one that stood out was they were different sizes.With the K3 being about a inch longer than the F. One quote i remember was one member telling me that if i put a K3 tank on a F that the seat wouldn't close. So i went out and found someone that has a CB550F2 and a CB550K3 to put this to the test.
I sent him the measurements of my tank just to see if there was any difference. The first result was the two tanks that he has are identical. OK, the K3 he has is unmolested, so the tank on his F2 is wrong maybe. He then went on to use the measurements from my tank and found that they were all the same.     

[matthewmosse]

Interesting. I find it all very confusing as in the past I carried on in blissfull ignorance and assumed all 500 and 550 bits were interchangable - if they were not I often just made sure they did fit with bodgery. Now I have internet and am aware that taking Mr hacksaw to a good seat might well end up robbing me the chance to swap a wrong seat for a right seat. Better result, but more stress.

[Steph550]

If I'd seen this yesterday I could have double checked for you, my other half has a nice original 550K3 in the garage along with my F2... I'm now away from home until the weekend but can have a look when I'm back if you like.

From memory and from the photo below I would say the tanks are the same, seats are definitely different.



Had a great ride on the F2 yesterday around the New Forest, showed the guys on their old Triumphs and Nortons that a girl on a Honda can be pretty quick too... 

Steph.

[Trigger]

Cheers Steph, it is a debate that has gone on too long. So your bike is no longer a ghost  . Yep, it was very nice yesterday at 19 degrees.

[matthewmosse]

I think I recall something in the Broolands book about the differences being carbs, seat, and exhausts from memory.

[Trigger]

Plus wiring loom, switch gear ect,ect.

[Steph550]

Oddjob for some reason the F2 did have the different mudguard with the front stay, while the K3 had no front stay.

There are so many differences between the two models, some big and some very minor. Our two bikes also feel totally different to ride, the carbs make quite a lot of difference as the F2 seems to feel a bit more lively when accelerating, but the K3 seems to feel more settled at 70mph+ (although this may also be because the K3 has had a full restoration whereas my F2 hasn't!). The exhaust noise on my F2 also makes it feel like you're going faster... whereas the K3 is so quiet you can hardly hear the exhaust above the wind noise.

I'll double check the tanks at the weekend Trigger. Gives me an excuse to visit the ghosts in the garage again! Hopefully the weather will be nice and I'll be able to go for another ride 

[Piki]

Hello, I have one CB550 K3!!! the head engine are different, CB550F has the holes of the "vacuum" over the manifolds and CB550 K3 has the "holes" on the carbs body. I have one CB550K3 enginge with CB550F engine head and for this reason I have two different places to "install" the "carbtune" on the head engine or on the carbs

[Steph550]

Looking at the parts diagrams on CMS, it shows the single stay mudguard for the USA 550F2, and both options for the UK model. I have a UK parts book at home so I'll check it at the weekend. I also have a 1977 UK magazine advert for the 550F2 showing the mudguard with two stays, so it looks like you could be right in that the US models had the single stay and most UK models had the twin stay.

Honda did make life complicated for themselves (and us) didn't they!

[Bryanj]

Piki, The cylinder head is the same for both only the inlet manifolds differ

[Piki]

Yes Bryanj, you are right!!

[andy_c101]

Steph,
I'm dead envious of the condition of both your 550's.
especially four gleaming 4-into-4 pipes on the K3.

My K3 is (still) on the lookout for the last one of four ORIGINAL pipes (No4 cyl) 
- the last of the "hens teeth" one might say!

here's a piccy of mine down alongside the flooded River Severn.

[Steph550]

I paid a visit to the garage today (unfortunately only time for a short ride  ) and had a look at the tanks on the 550F2 and K3. As far as I can see the tanks are identical, measured them and they are the same size.

Oddjob, I also had a look at my F2 parts book, it turns out the mudguard with the front stay was only used on English and European Direct Sales models, all others had the same mudguard as the K3.

Thanks for your nice comments on the K3 Andy, yours looks lovely too and glad to see you've been out enjoying it. Unfortunately due to lack of space (/too many bikes!) the K3 will be up for sale soon  It will be a reluctant sale as it really is lovely but a 750K0 has just moved in to the garage, meaning we really can't move in there any more!

Steph.

[Trigger]

Thanks Steph. So there we have it boys and girls, the tanks are the same.

[Norniron]

No theyre not the k3 has a chrome trim around its rim