Topic: How Similar is the CB550 and CB650 Frames? Ever mounted a Dunstall tank on one?

[Namba1032]

Hey guys,

I've got this CB650 that I've been restoring for a while as a cafe project and the biggest problem I've run into is finding a tank for it. I want to put a dunstall tank on it and but finding one that will fit over the backbone has been a problem. I actually found an original one hoping it would fit with no such luck. Its really close, but not quite... I have heard that the CB550 frames were very similar to the 650's so maybe you guys can help me out here to. I am contemplating just going out and buying a replica dunstall tank from moto tumbi (heres a link http://www.classic-motorcycle-fiberglass.com/tanks/Dunstall%20CB750%20Tank.htm ) Has anyone ever mounted one of these up on a CB550, CB650, or have any idea if one would fit?

Heres some pics of my bike

mocked up with the dunstall tank i have now.

Any info is appreciated

Brian

[bill440cars]

             Can't really help with the tank mounting info, but I can tell you that the 650 motor will bolt into the 550 frame and, I believe the 500 frame as well. There are others here who have far more experience with the swapping of these parts and about the tank mounting I'm sure.

                                                Later on, Bill

[Jim F]

well here is my Dunstall stuff but I am still going to have to make some mounts for the tank

Jim

[physician]

i have both 77 cb550 ans 81-81 650. i can take measurement and picture if you want

[Namba1032]

Well I guess my question is does this particular dunstall tank have enough tunnel depth to accommodate the large backbone? If the backbone on the 500 or 550 is similar, maybe someone with one of those bikes could give me some info on mounting a tank like this. The biggest problem with the tank I have is that the tunnel isnt wide enough to fit the coils under it.

Brian

[Namba1032]

Hmmm...
    I'm not very familiar with the 650 frame, but when the Dunstall tank is installed on the 550/ 750, there is plenty room for the coils. I sometimes move the wiring from the headlight bucket to the coil area to clean up the area under the gauges. The 650 frame may have more of an arch in the tank area.  Does the tank fit with out the coils?
 Daniel

Hmm Im guessing that your tank has much more room in the tunnel than mine does. Check out the pics and let me know what you think.

[Namba1032]

Yeah yours has waaay more room. Thanks for taking the time to take the pics for me, I really appreciate the help.  Is moto tumbi the only place to get one of those tanks? I might just sell the one I have now and buy one of those. Do you have any idea where I could get one the for the best price besides e bay?

Brian