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Discussion Starter #1
Ok, so I admit, this is not the most severe mechanical problem any of you have ever heard of, nor I for that matter. However, it is a problem, and so help me god, I can NOT find a solution.

The bike: 1971 Honda CB450

The problem...

So I purchase this beautiful 71 CB450. Take it home, tinker a bit and it runs. Since then I've done all the fuel, timing, and other random mechanical issues. The only problem I cannot for the life of me fix? The seat and the gas tank do not, will not, can not match up. I know what everyone is thinking...I'm an idiot. One or the other is wrong. BUT...hear me out.

Everytime I attempt to close the seat, it simply rests on the edge of the gas tank. Does not latch, does not lay on the frame rails, just sits on the edge of the tank with 2"-4" inches left to hitting home. The seat did not have a hinge when I brought it home. So I bought one off Ebay for about $8. The item description read clearly "Seat Ducktail Hinge, 19714 Honda CB450". It arrived, and I bolted it on in the obvious manner it was supposed to go. I know I did this because the hinge was perfect. There were lines in the paint on the underside of the seat after years of the old hinge being there which told me "you are putting this on correctly". Bolted on, smile on my face, I lay the seat down. Seat stops at the edge of the gas tank, smile dissapears, and frustration quickly sets in.

What to do? I take the seat back off, and attempt to re-assemble the hinge in some other way. Not possible. The hinge is correct. Maybe the gas tank has a problem...nope. For 4 long hours I moved, adjusted, scratched my head, and adjusted some more. Now for the grand finale, are you ready to laugh?

I did. I bought another seat. Again to Ebay, for $19.95. "Seat, OK Condition, Small Tear. Honda 1971 CB450". A few days go by, I get another seat, bolt it up (the same lines from the same hinge!) and lay the seat down. Again the seat humps the gas tank. :x Then I threw a wrench and broke a window. So here are the facts...

The bike matches color. The headlight, the forks, the tank, the sidecovers, everything painted matches to a "T". Perfect. So I think there's no way the tank is wrong. The reason I say this is because it slides ever so easily onto the rubber ears from the frame. The tabs on the tank fit perfectly into the rubber mount in front of the seat latch. The seat (both of them actually) bolts on perfectly with the hardware and hinge, closes and works beautifully...with the gas tank removed. However, I lied a few lines ago. That was not the grand finale, but this is...

I bought another gas tank. Again to Ebay, "Gas Tank, 1971 Honda CB450. Minimal Rust). And a few days later? No item. The user never shipped, disappeared with my $50.96, and I never received my gas tank. I now have an action against him, $50 less money being withheld by PayPal, two seats, and a 1971 Honda CB450 with a gas tank and two frame rails.

Questions to myself:

-Did somebody take this motorcycle, and ride it with no seat? :lol:
-Did somebody take the time to switch all painted and colored parts from a different bike in order to keep MY gas tank before selling me the bike with the wrong tank? (Which of course would mean that theirs would not fit also!) :shock:
-Did I receive one seat with the bike, and purchase another for the same bike, but both items are wrong, even though the patterns to bolt it on are correct? :?
-Do I have the correct items, but am not intelligent enough to assemble them correctly? :oops:

Is there anybody in the Honda Twin Universe that could possibly know something about this problem or issue, and please help to restore my sanity? Any input, any at all, even a small inkling of a hint would be more appreciative than you could possibly imagine.

Now it's time to start drinking before I break more items.
 

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I'd like to help you out since I have a '71 450 sitting in front of me with a good working seat. Post up some pictures of the bike/seat problems along with some pictures of the hinge assembly. The rear hinge is probably not the problem. Are you sure you have the latch installed correctly? It's easy to put that on backwards.

Again, post some pictures that I can compare against with my own assembly.
 

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pictures of seat, hinge, frame, gastank ect.?
 

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CL and CB450 tanks/seats are different from each other.
Try to use a CB tank with a CL seat (and vice versa), and you run into things like this.
However, the frames are the same, so the front and rear rubber mounts do match up to both tanks. The rear hinges will also match up perfectly.

Photos should allow us to see what's going on right away......
 

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Sensei
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I'm with Bill on this one....I'd bet you have a CB tank, and a CL seat.....
 

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Discussion Starter #6
I will get some pictures and send them later on today. Thank you for the suggestions, I thought the same thing also, and here are my thoughts...

-The seat hinge is not possible to bolt on wrong. There are faded lines clearly showing where it needs to go, and any other way of bolting it on cannot work without manipulating the metal via torching and welding.

-With the tank removed, the seat sits and latches beautifully.

-If we go with the presumption that they are mismatched, then deductive reasoning would point to the tank being the most likely culprit, because the seat which came with the bike matched with the seat purchased on Ebay. Also the seat purchased on Ebay, and the hinge purchased on Ebay were clearly for a CB450. Which leads me to...

-Why and how could someone go through all the trouble of putting on the wrong tank...I also have doubts about this. Reasoning is the pinstripes match, the paint matches, they "seem" to have the same weathered look, etc, etc. And finally...

-If it's true that tank/seat are opposites from a CB and a CL, how could the previous owner possibly have ridden it?

Photos you will get, I promise you this. But I fear that my head is ready to explode.
 

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Sensei
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The seat may be from a 450, but not likely from a "CB" 450....This is why the "hinge marks" and hinge fit and the latch works so well, but the seat won't close on a CB tank....The longer seats were for the "CL" models.

CB...Longer, bigger tank, shorter seat
CL...Shorter, smaller tank, longer seat

Note that the mounting points were the SAME for both models... The CL tank had a longer "Tang" that fit UNDER the seat to make up the additional distance to the rear mount rubber.......
Often, the Honda part code (three digit) will tell which part you have, and seats were often stenciled with that code in yellow or orange on the bottom.....
CB 450 codes.... 283 .... 292 .... 319 .... or 346
CL 450 codes.... 294 .... 320 .... or 347

The variety of different codes indicates which "K" the change applies to... As you can see, there were several differences involved....
Steve
 

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I feel for you. I got a '76 550-4 project a couple years ago that had the exact same problem. I learned the difference between the K and F models that summer. Since my seat cover and stuffing was wasted, I just cut my seat pan down a couple inches in the front and recovered it myself. No interference problem, no buying more parts, kept the tank I just painted. Crude, but effective. Not that I'm suggesting this, just that I CAN relate. :D
 

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Discussion Starter #10
Hello everyone!

Sorry about yesterday, as I promised the pics, but I didn't get around to it. It was in fact the first thing I did when I got home today. So, here we go...

Here is the bike in general overall view, and as you can see the seat is clearly not closing. The main thing in this pic is that the tank matches everything else. Please don't mind the dent.

[attachment=4:e4pmk5io]DSCF0027.JPG[/attachment:e4pmk5io]

And here is the pic of the underside of the seat. The hinge is correct, the stay bar lines up, and without the tank on the seat will latch perfectly.

[attachment=3:e4pmk5io]DSCF0029.JPG[/attachment:e4pmk5io]

Here is a pic of the tank tab fitting into the rubber mount. It also fits perfectly, as do the ears on the front.

[attachment=2:e4pmk5io]DSCF0032.JPG[/attachment:e4pmk5io]

And a pic of the old seat, received with the bike, and it's the exact same as the new seat I purchased.

[attachment=1:e4pmk5io]DSCF0038.JPG[/attachment:e4pmk5io]

For those of you serial readers, here's the stamp.

[attachment=0:e4pmk5io]DSCF0037.JPG[/attachment:e4pmk5io]

So, now that everything has been shown, I'm sure you see my predicament. If, in fact...

-With the tank removed, the seat latches perfectly
BUT
-Without the seat, the tank matches paint and mounting hardware perfectly, that tells me that...

-A new shorter tank wouldn't fit the same mounting hardware, because it in fact would be too short,
BUT
-A new seat still could not be short enough to hold the same mounting locations, ride on the same spot on the frame in the closed position, and be able to latch behind the tank that is on the bike.

Again, any answers here would be absolutely amazing, because unless I have some error in my thinking, this simply does NOT make any sense to me. Help?
 

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No mystery here -

Looks like a CL K1-K3 seat to me.
Won't work with a CB tank, you'll have to change one or the other.
Like I said, all the mounts for everything, as well as the frame, are the same.

Nice CL tanks are hard to find, so are seats......
 

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Discussion Starter #12
So if that is the case, the proper CB seat would have to be ALMOST identical, but for a smaller crown in the front? And also, that means I have two CL450 seats?

Sale or trade, PM me if interested. As you can see, one has been recently recovered, and the other has good foam, no cover. Hinges included in both, or either one. Willing to sell, or trade for the PROPER one.

And if anybody could give me some dimensions (the seat I bought was clearly labeled CB450) so that I don't have this mistake again, I would greatly appreciate it.
 

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Discussion Starter #13
And one more thing...I'm ready to completely customize this tank. I've had it off so many times, but that connecting hose that runs under the frame allowing fuel to flow back and forth is driving me crazy. Anybody solved this problem? I was considering cutting them off, welding it closed (safely, of course), and being done with it. However, I don't exactly know how bad the repercussions are of sucking fuel from only one side of the tank. I also thought about two petcocks. Either way I haven't decided, and I got so sick of disconnecting that line that I actually ran a longer one up under the tank but over the frame, just for a temporary fix. Experience in this is appreciated.
 

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Well, EBay sellers sometimes are mistaken.
Since your tank is messed up, why not try a CL tank?? There's a nice primered one on EBay right now.

Unless you're restoring it, then you need a real CB seat.
I'm sure you could sell both your CL seats on EBay.........

CL seats are a bit longer overall, and have different pleating patterns than a CB.
Sorry, I don't have any measurements for you.
 

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NathanMT01 said:
And one more thing...I'm ready to completely customize this tank. I've had it off so many times, but that connecting hose that runs under the frame allowing fuel to flow back and forth is driving me crazy. Anybody solved this problem? I was considering cutting them off, welding it closed (safely, of course), and being done with it. However, I don't exactly know how bad the repercussions are of sucking fuel from only one side of the tank. I also thought about two petcocks. Either way I haven't decided, and I got so sick of disconnecting that line that I actually ran a longer one up under the tank but over the frame, just for a temporary fix. Experience in this is appreciated.
Yeah, it sucks.
some guys put quick-disconnects in that line.
There's no harm in running without it, other than you really cut down on the effective tank capacity, and might get some unpleasant surprises........
 

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Here is a picture of a restored '71 450 seat that installed on my bike. The foam and pan are original only the cover is new. The measurement from the front to back (taken on top of the seat from the front "piping" to the rear "piping") is 23.5" if that helps.

Steve and Bill are wise than I re: these things but I would not remove the tube between the side. I think you'd have a severe balance and quantity problem when riding the bike. If the tube is a problem while you're working on the bike then just put a couple stubs on each side and plug them with a 1/4" bolt. When you're finished working on the bike then put the tube in place and ride as usual. I have some hemostats that I use on the tube and I have cut the hose in the middle and installed a brass coupling. If I need to remove the tube then I use two of the hemostats (one on each side) to clamp the hose then just remove the coupling in the middle and I can take the tank off without a bunch of fuel spilling all over.

Mike[attachment=0:11lsj0bi]PICT1263.JPG[/attachment:11lsj0bi]
 

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Man those disconnects are cool.
 

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Discussion Starter #19
Thank you, thank you, and thank you! The seat problem has been taken care of, and as I promised, I am extremely grateful. While it may not seem like such a big deal, it was to me. Everything matches up, everything makes sense, but didn't fit. I've been liberated!

About that tank...I still haven't decided what to do. The disconnects I did think of, we sell them at our store (I work at a dealership). But I don't think I believe that it would cause that much of a balance problem. The reason is, I've seen so many, many, many bikes come through the past years which had the same design. I.E. a split tank, but hung even lower at both sides, and very few with these crossovers. All the Japs are known for this, and it's always made me think of why they do that. It could be fixed with what I actually HAVE thought of, and it's is something that would work, but I'm absolutely not going to do.

Cut the tank open, and put a line IN the tank. Steel, aluminum, rubber, it wouldn't matter. As long as it was in the shape of an upside down "U", and the angle wasn't very great (it would have to be in the back of the tank) it would create a natural suction, or siphon. It would actually be perfect, because even the lowest change in pressure on the right would cause suction from the left, and when the balanced out the suction would stop.

As I said, I'm confident it would work perfect. But I'm not doing it. :)
 

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NathanMT01 said:
Cut the tank open, and put a line IN the tank. Steel, aluminum, rubber, it wouldn't matter. As long as it was in the shape of an upside down "U", and the angle wasn't very great (it would have to be in the back of the tank) it would create a natural suction, or siphon. It would actually be perfect, because even the lowest change in pressure on the right would cause suction from the left, and when the balanced out the suction would stop.

As I said, I'm confident it would work perfect. But I'm not doing it. :)
except it wouldn't work, as the tank filled it would trap a air bubble in that line, then as it emptied there would be no siphon effect, try it with a couple jars and some plastic hose
 
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