looking for a good fuel tank - 81 CB650C

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thegentleman
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looking for a good fuel tank - 81 CB650C

Postby thegentleman » Sun Sep 02, 2012 3:23 pm

Good day ladies and gentlemen,

I am having trouble finding a gas tank that will fit my '81 CB650C. Does anyone have any leads, or perhaps an 80 or 81tank laying around?

I live in Toronto, postal code M6J 2L7.

Any help would be greatly appreciated.
1981 CB650C

cb650
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Re: looking for a good fuel tank - 81 CB650C

Postby cb650 » Sun Sep 02, 2012 5:02 pm

A 82 standard will work too. Try to get a petcock with any as there is some bung size differences.
Did you clean the tank out?!?!?!?!

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thegentleman
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Re: looking for a good fuel tank - 81 CB650C

Postby thegentleman » Sun Sep 02, 2012 5:57 pm

That is good info, thank you cb650.

Can you (or anyone) tell me what fuel tanks will fit without moving the mounting holes? There are a lot of 82 650 SC tanks out there, which I assume are not standards (also not a very desirable tank shape).

So far, I know with proper petcocks, '80 650, '81 650, '81 650C work.

On a related note, does anybody know how good POR 15 is at sealing pinholes? Or any other method? My current tank has one near the bottom, which drips gas at a rate of one drop every three days or so. Slow, but still cause for concern.

Cheers

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Re: looking for a good fuel tank - 81 CB650C

Postby onepieceatatime » Sun Sep 02, 2012 8:01 pm

thegentleman wrote:That is good info, thank you cb650.

Can you (or anyone) tell me what fuel tanks will fit without moving the mounting holes? There are a lot of 82 650 SC tanks out there, which I assume are not standards (also not a very desirable tank shape).

So far, I know with proper petcocks, '80 650, '81 650, '81 650C work.

On a related note, does anybody know how good POR 15 is at sealing pinholes? Or any other method? My current tank has one near the bottom, which drips gas at a rate of one drop every three days or so. Slow, but still cause for concern.

Cheers


'80 cb650 and cb650C, '81 cb650 and cb650C, and '82 cb650 with the petcock will work with no modification to the frame or tank. The fuel line size is different on the '80 model bikes though, so you will have to adapt it, but cb650 posted somewhere a inline fuel filter with 2 sizes on each end.

The SC tanks will not directly fit.

Caswell tank sealer is a good one, and can take care of pinholes.
http://www.caswellplating.com/restoration-aids/epoxy-gas-tank-sealer.html
Folsoml wrote: Good judgement comes from experience. Experience comes from bad judgement. :lol:

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Re: looking for a good fuel tank - 81 CB650C

Postby cb650 » Sun Sep 02, 2012 10:31 pm

There was junk for SC tanks when I needed one. OK one NOS beauty for 400 but the other two looked like shit. Ended up getting one from a member here or on sohc4. Need to get a hold of him to so hopefully he will see this.
Did you clean the tank out?!?!?!?!

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Re: looking for a good fuel tank - 81 CB650C

Postby thegentleman » Thu Sep 06, 2012 7:37 pm

So I found an '80 tank in great condition, it is being shipped with the petcock. When it arrives, can anyone tell me what I should expect to install it on my '81 C? I know the fuel line is a different size, but will the new petcock simply fit my current setup with major modification?

It's going to be a long winter, planning on doing a full rebuild. I'm really looking forward to it, but nervous at the same time! Any words of wisdom?
1981 CB650C

onepieceatatime
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Re: looking for a good fuel tank - 81 CB650C

Postby onepieceatatime » Thu Sep 06, 2012 7:42 pm

You should be able to just put the tank on and go once you resolve the fuel line size difference. No modification required.
Folsoml wrote: Good judgement comes from experience. Experience comes from bad judgement. :lol:

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thegentleman
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Re: looking for a good fuel tank - 81 CB650C

Postby thegentleman » Thu Sep 13, 2012 6:50 pm

onepieceatatime wrote:You should be able to just put the tank on and go once you resolve the fuel line size difference. No modification required.


The tank came in today, and it is in great shape. I am planning on taking some progressively finer sandpaper down to bare metal and coating it inPOR-15 GLISTEN. Two or three coats should do the trick? Anyone against this, or have experience with coating a bare metal tank?

Also, what do you mean by "resolve the fuel line size difference"? I haven't taken the tank off yet, but want to know what if anything else I will need to swap these tanks...
1981 CB650C

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Re: looking for a good fuel tank - 81 CB650C

Postby onepieceatatime » Thu Sep 13, 2012 8:22 pm

onepieceatatime wrote:The fuel line size is different on the '80 model bikes though, so you will have to adapt it, but cb650 posted somewhere a inline fuel filter with 2 sizes on each end.



http://www.hondacb650.com/viewtopic.php?f=3&t=6610&p=44032&hilit=fuel+filter#p44032
Folsoml wrote: Good judgement comes from experience. Experience comes from bad judgement. :lol:

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thegentleman
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Re: looking for a good fuel tank - 81 CB650C

Postby thegentleman » Wed Sep 26, 2012 11:09 pm

So I finally installed the new tank—which is in fact one year older than my original. It is in great shape, but still Evapo-rusted it for two days to be sure. A little flash rust occurred but seemed to stem that with a gasoline rinse.

But to the real reason why I'm here: I have another possible solution to the fuel line discrepancy issue! As we all know, the 1980 CB650 has a different bung for the petcock, and the petcock fuel line ID is 1/4". The 1981 CB650C has 5/16" ID fuel line. It was damn near impossible to find that universal in-line fuel filter that would join the two sizes locally. I also did not feel comfortable with a flimsy plastic doohickey so close to the manifold—I would imagine that over time or on long rides it would get hot and somehow manage to warp or melt, impeding the flow of gasoline and adrenaline.

So... after days of running around, I cam across some 5/16" outer diameter fuel injection hose. It fit very snug on the 1/4" petcock barb, increasing its diameter approximately 1/16". The existing 5/16" fuel line fit snug over the newly thickened barb, couple with a proper fuel line tie and that baby isn't going anywhere.

It is the cleanest MacGyver job I have come across with maximum flow. Just have to make sure the in-tank filter is in good shape! I hope some poor chap looking for a solution can find this some day, it would save him/her hours of pulling out their hair and/or wanting to punch every big box store employee in the face.
1981 CB650C

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Re: looking for a good fuel tank - 81 CB650C

Postby cb650 » Thu Sep 27, 2012 2:31 am

I have been running one of those plastic doohickeys for over 15 years. Never had a problem. Yes you can jam a small hose on a big barb or crimp down a big hose on a small barb. Did that also for years untill I got the plastic POS. Those filters will take more heat than your engine will put out before it seizes.
Did you clean the tank out?!?!?!?!

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Re: looking for a good fuel tank - 81 CB650C

Postby PAVALKER » Sun Dec 09, 2012 9:20 am

So what did you do with your original tank? What shape is it in? Pictures? Looking for a tank for one one of my CB650C's....


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