replacing '83 tank with '82

[rotordrvr]

Long time reader, first time poster. Experienced mechanic.
Just found and bought after searching for several years, a NOS tank for my '83 550 Vision. My original tank had been repaired (not by me) with what looks like fiberglass or something like it and then coated to ostensibly protect the repair from the fuel. Its been slowly coming apart since I got it and now the petcock (new last year $$$) is pretty much constantly being clogged with tank liner material that is coming off.
The problem is that the NOS tank is an '82 and the petcocks are different. I toyed with the idea of modifying the '82 tank to fit an '83 petcock, (I'm going to repaint it anyway because its grey and the bike is black) or rebuilding an '82 petcock (just try finding a new one) and mounting an '82 fuel pump with the pressure regulator to match; just going without any fuel pump using the '82 petcock on the NOS '82 tank; or mounting an electric fuel pump.
Any suggestions/thoughts?

[fret not]

There is a reason the XZ has a fuel pump instead of depending on gravity like most motorcycles do.  Apparently gravity works well enough for the first part of a fill up but soon becomes less than needed.  Also to consider, there is no facility for the fuel gauge sender on the '82 tank.

I have an '82 with 'other' carbs, so I will plumb an electric pump into the system.  It seems that for some of us the journey is the destination.

[Walt_M.]

I have an '82 tank and petcock and electric pump on my '83 and I'm happy with it. I miss the fuel gauge a little but it wasn't that accurate anyway.

[briandneville]

Getting NOS tank is a rare find.  Well done.

'82 petcocks are not unusual on eBay, and maybe someone on this forum has one they can part with.  Rebuild kits for them are available, apparently.  I know Bruce Neilson recently rebuilt his with a kit.

The idea of using an '82 fuel pump / regulator seems reasonable, as that part is not really integral to other carb components.

I think your biggest challenge will be figuring out what to do with the fuel return line from the '83 carb.  I recently capped this line on an '83 when the tank was off and I didn't have enough hose to connect it to the petcock.  The engine ran fine, but there was a significant flow of gas from the drains.  This was corrected with the tank installed and the return line properly connected.  Suggests that the return fuel was finding another way into the drains.  I do not know how that happens but those carbs have a number of passages that I have not been able to truly understand.  Maybe the '82 regulator will solve this?

I'd say if you have an '82 tank, you need '82 carbs.  Not hard to find on the www, but another big unknown.  Best of luck.

[rotordrvr]

Thanks everyone for your insights. I have since read the thread on this forum concerning running the vision sans fuel pump, but that doesn't really address the '82 - '83 carb/tank issue. I can live without the inaccurate fuel gauge but from what I've read, I'd be better off keeping the '83 carbs and that means I need an '83 petcock. I'm handy enough with the welder to cut the petcock mount from the rusty/repaired '83 tank and transplant it to the '82 tank. It'll make a nice winter project. I need to repaint the '82 tank anyway because it's a European model from Germany done in gray and my bike is black. The things we do for the things we love, eh?

[Ken Williams]

Just in case someone doesn't realize, '83 fuel pump utilizes the tank return to limit fuel pressure.  Plugging this line should overpower the floats if the pump is functioning properly. 

[briandneville]

Ken-that would explain the observation I mentioned in my previous post.

[jefferson]

I believe the return line was to keep the fuel cooler and to help with the running issues they had. A number of people have used 82 petcocks with 83 carbs and have not heard of any issues. The pumps put out the same pressure, but the return line just let excess fuel return to the tank.

[Ken Williams]

I also believe the return line was implemented to reduce heating of fuel in the lines and carbs.  I surmise the designers took advantage of the resulting passive fuel pressure regulation to gain a modest cost reduction.  If a '83 pump functions with no return, I suspect a stretched diaphragm or other problem is compromising pump output.  Based on my experience, a stretched diaphragm will eventually lead to insufficient fuel delivery issues.  If the return is connected to the line from the tank, then fuel flows only by gravity, same as running without a pump.