How to put this thing together? I picked up a partially completed '72 CB450..

[kcramp]

Hey all,

I picked up a 1972 CB450, and I'll be honest, I have SOME clue as to what I am doing.

The thing came with a BCR Dolphin seat+tank combo, but I can't figure out how to get the seat to attach, let alone bolt down the tank.

The seat seems elevated on the frame, and no mounting holes line up. I found a piece in the box of parts that it attaches to almost perfectly, but it is not painted and looks like it was removed on purpose...Or it is supposed to be attached to the frame somehow? Can someone take a look at these pictures and explain to me what's going on here? Thanks!

See larger pictures here, don't forget to look at the descriptions!: http://imgur.com/a/9ztFM

 

[work9to5]

That piece your holding is meant to be welded on to the frame. After you cut the frame. See how its got (at the end of the tubes) smaller tubes diameter tubes? Those are meant to slide into the existing frame (after its cut) so that structurally the weld is sound. Basically make friends with someone who knows about bikes and a weldor immediately. Good luck!

 

[TheCoffeeGuy]

The Braided hose lookes like a crank case breather tube possibly. I cannot see where the forward end is connected. If it is a Breather Tube, there should be a short pipe connection sticking out of the back of the Rocker/Valve cover on the top of the engine. Factory has this tube as a thin walled black tube running down the frame and exiting ahead of the swing arm pivot below the front of the seat.

 

[jpmobius]

+1, and +1. The BCR seat is likely elevated because of the 4 tabs with the 90 degree bends that have been added to your frame. They are not stock and likely were for a previously installed aftermarket seat. Looks like yu will have to cut them back off. Before you do anything, Take the spring off one of the rear shocks and re-install it by itself, leaving the other shock off the bike. This will show you the maximum travel of the rear suspension so you can figure out where your new framing can go. Fasten that framing assembly into the seat, and locate it on the bike to see where you need to cut the back section of the frame. Once you do that you can mock it up on the bike and check for tire interference with the new framing elements. It looks like there will be, but you can sort all this out before you think about welding anything.

FWIW, consider rounding up a factory fender and incorporating it. Bikes suck without really good functional fenders, though they can be substantially cut down from factory size and still deliver most of the performance. I personally don't mind getting sprayed with water from the tires, but trashing the engine and the rest of the bike should be prevented - opinions vary of course.

Also consider this: If you cut the back of your frame off behind the shock mounts and eliminate the upside down "U" shaped brace you will be replacing a very light, elegantly engineered (if ugly) component with a dreadfully heavy and utterly unnecessary bunch of hardware (except that it mounts the seat of course). Additionally, presuming you will be putting the battery there, you will be relocating one of the heaviest and most optimally located components on your bike to probably the worst place imaginable. I realize this is very popularly done with the goal to create that open triangle under the seat - looks great, but a smaller, lighter, less visible battery mounted forward would be an improvement. You may be better off removing the existing seat mounts, not using the aftermarket framing, not cutting off the factory "hoop" and figuring another way to mount the seat and a smaller battery.

 

[kcramp]

Thanks all!

jpmobius, I am going to cut off the elbow brackets and find a way to mount the seat to the frame without welding on the hoop -- you make very valid points.

 

[J-Rod10]

If you are wanting to relocate a battery, looking into a LiOn battery. I have mine under my seat, it weighs 1.4lbs.