cl77 gas tank differences

[jleewebb]

The last time I removed my gas tank I had a flash and did something I hadn't thought to do before: after syphoning as much gas as possible out to the tank I slipped a cut-down milk jug in under the petcock and carbs, removed the sediment bowl on the carburator, and turned the lever to reserve. Removed nut holding back of tank so I could lift/move the tank around to get all the gas out. Then took petcock loose from the tank pulled off hose to crossover nipple, left other hoses attached to petcock, and removed tank. Didn't spill a drop, in contrast to customary flamable mess I've created every time removing tank in the past. Duh!

[s2000erick]

+1 on davomoto's quick disconnect recommendation from motion pro.

[e3steve]

Gramey7,
I'm no physics major but I have it on good authority that fuel don't flow up hill to get to the other side but when you work on these old critters as much as I do and need to pull the tank often, it's nice not having to deal with that tube. Me thinks that is what Honda engineers had in mind when they made the change to the seamed tank.
I did once, in the presents of a group of Harley riders, leaned my scrambler over to slosh some gas just to make sure I made it to the station. "Bet you can't do that" I said with a grin, just my goofy country sense of humor I recon, Rw

Oh yes it does, me ol' Hondamate! However, two factors must remain:

• There must be no air whatsoever in the crossover pipe
  The pipe's level of exit must remain lower than the level of entry

The pipe then becomes a siphon and not a crossover/balance pipe.

On a bike both these factors cannot be guaranteed, as relationship between each side is constantly changing, but it works on a static tank.

Just to clarify (not trying to be clever, just explaining):

• Scenario 1 - empty tank & siphon tube
  Fill tank at pump, one side first; fuel floods across from the lowest point in the tank
  Air gets trapped in the siphon's highest point so it won't work
  
  Scenario 2 - Fill both sides of tank
  Siphon eventually becomes purged of air due to sloshing
  Ride bike, fuel level drops to a low level
  Crank over around a bend or two
  Air enters siphon from the emptier side so it won't work

It's why some older Brit bikes had two petcocks and a dual banjo at the float bowl. Honda designers saved the money with a balance pipe.

I got a dual-shut-off mating valve from Sirius Consolidated Inc (eBay's siriusconinc); it has five-sixteenths-inch (8mm) spigots, though. A bit if a stretch for the OEM rubber 6mm fuel pipe (I hate the plastic pipe!) but it does work

[G-Man]

You might just pull a wheelie as the tank empties - that'll sort it!

G

[rustywrench]

Steve, I forgot about the syphon factor but ya really can't depend on the conditions to be right.
I tried to find a quick disconnect locally and gave up as too expensive. Just a lot cheaper to re-route the tube and be done with it.
A wheelie on a 305 scrambler??? Now really Gman, not at my age even if you could do it on one of these. It would work though I suppose. Rw

[LOUD MOUSE]

Back around 1985 I bought a 1967 CL77 with a flat front tire.
The engine ran well so I bought it and put air in the tube.
Well the tire held air so I started it and rapped it up a bit then let out the clutch and to my absolute amazement that CL did a wheelie!
First and last time for that!!!!!!!. ......lm

Steve, I forgot about the syphon factor but ya really can't depend on the conditions to be right.
I tried to find a quick disconnect locally and gave up as too expensive. Just a lot cheaper to re-route the tube and be done with it.
A wheelie on a 305 scrambler??? Now really Gman, not at my age even if you could do it on one of these. It would work though I suppose. Rw

[e3steve]

Steve, I forgot about the syphon factor but ya really can't depend on the conditions to be right.
I tried to find a quick disconnect locally and gave up as too expensive. Just a lot cheaper to re-route the tube and be done with it.
A wheelie on a 305 scrambler??? Now really Gman, not at my age even if you could do it on one of these. It would work though I suppose. Rw

My point exactly, chum. Using siphonage to balance two depositories only works well if they're static, on the same level and remain so.

What does work well is to install a longer balance pipe and create a loop between the carbs; then, when you just need ready access, stuff a strip of 2" foam around the fwd edge of the tank and raise the aft end onto a wooden batten between the tank and the frame. Good with rubber fuel pipe -- not so good with PVC. Be careful not to unbalance the tank though, as it can roll off if you move it too far away from the front cushions!