Topic: CB550F tank on 550K

[Ms Tokyo]

Need some advice on fitting a’75F tank on a ‘76K. Couldn’t pass up a deal on a rust free tank. Tank is longer and more narrow underneath. Thinking I will need to trim the posts for rubber mounts up front and may need to lift rear up slightly to clear the frame that is too wide for tank to fit over in rear. Probably need to make some type of bracket for rear. Looking for advice before jumping in.

[Little_Phil]

AFAIK there were only two different styles of tank over the entire 500/550 range. Three maybe as style one had two different petcock mounts over the years. All will fit to the rubber front mounts and the rear mounts. The larger F and 550F and K3 and 1978 tanks overhang longer at the rear and cannot be used with the seats of the earlier models without modification.

[Ms Tokyo]

Tank is definitely longer but not a problem since I am making a seat. Up front the posts are too wide and will need to be trimmed. I am more concerned that the tank bottom is not wide enough to fit over the frame. I will have to raise it and make some type of rubber pad to keep the tank from riding on the frame metal to metal.

[TwoTired]

Something is off here, as all my F and K tanks will swap onto frames easily with the seat off and no modifications.

You certain you have a tank from a 550 F model?

Cheers,

[Ms Tokyo]

I went back and looked at the tag that was attached to the tank when I picked it up. It says 1974 CB550. This tank is about 2-3” longer than the tank that was on my ‘76 550.

[ekpent]

 Be best to take a picture of the whole gas tank so people can take a peek including the top, side and bottom.

[TwoTired]

In the US, the F style tank wasn't on offer until 1975.

Cheers,

[Scott S]

 Show us a pic of the tank from the top/side. The gas cap location will tell us a lot. I wonder if you have a 750 tank?

[Bankerdanny]

The tank is longer, but the underside should be basically the same. As far as I know the only changes in the 550 frames were how the passenger pegs attached. Seats and tanks should swap easily between the F and K frames, you just need to make sure you have the right seat. An F tank needs an F or 77-78 K seat.

[Ms Tokyo]

I’ll get more pictures tonight but the cap is centered as opposed to the offset right cap of the K tank I removed.

[Ms Tokyo]

I found this thread and it may be the ticket.

http://forums.sohc4.net/index.php?topic=24708.0

Thanks for everyone’s input. Sorting out the correct petcock will be the next issue.

[Scott S]

 Yeah, that's a 750 tank. You can tell by the filler neck being centered instead of offset.

[Ms Tokyo]

Thanks Scott!

[Stev-o]

That 750 tank doesnt look so great, I'd be on the lookout for a 500/550 tank...