Topic: does a 750 cb tank fit a 650 cb frame?

[dwginde]

my 1st post!! Not sure I have the correct thread but here goes. I need help with a 650 cb project bike. I'm new to the cafe racer scene but have a chance to buy a nice custom "whale" tank and seat pan that was built for a 750 frame. The base of the original tank was used for the custom tank.I assume the seat pan may not fit without tweaking but I think the tank may bolt up fine. I'd appreciate any thoughts on this.

[CBJoe]

Welcome!

Backbone shape/size between CB750 and CB650 is different so I would be surprised if it would/could fit without modification.  Might be hard to get a good response as well because the underside of the custom tank likely isn't a 1 for 1 from a stock tank.

Is this a 1 off custom tank?  or is it a BCR or other aftermarket tank?

Obviously where there's a will there's a way... you can make anything fit.  Just depends on how much work you want to put into it.

Regards, Joe

[65Ch3v3LL3]

What year CB650 do you have? The 79 frame is different from the 80 - 82 frames and would be more similar to the 750 frames. I still don't know if it would be a direct fit but I'm sure it could be made to fit. The later frames have a dip in the seating area that would need to be flattened out to use any type of cafe racer seat pan. The later frames are generally made into bobber type bikes or brat bikes. Below are some images I stole for comparisons.

CB750 Frame


79 CB650 Frame


80-82 CB650 Frame with dip in seat area

[dwginde]

Thanks for the replys!! Unfortunately, my frame is an 80 and has the "dip" in the seat area. Kind of hard to fit the usual seat pan. May have to modify the frame

[65Ch3v3LL3]

Thanks for the replys!! Unfortunately, my frame is an 80 and has the "dip" in the seat area. Kind of hard to fit the usual seat pan. May have to modify the frame

I have seen others weld in metal to bridge the gap so to speak so that might work for you. Another option would be if you could source a 79 frame for cheap locally. Then you could swap everything over. If you are doing a complete tear down this might be the easier option.

[adrianm1972]

I fits just fine but you have to relocate the rear tank mounting point forward a little.....very easy to do.

I have a 76 CB750 tank on my 82' CB650.

Stock 82' 650 tank


76' 750 tank