No reserve?

[daoist]

I recently bought a pretty nice '77 just like the one I learned to go fast on in the 80s. Funny, it doesn't seem as fast as the one I had in the 80s... Anyway, it seems to have no reserve fuel capacity, it just goes bone dry no matter what position the petcocks are in. My guess is someone redid them at some stage and didn't put the reserve pipe back on inside the tank? It's been an eternity since I've had a manual petcock out of a gas tank. And my preferred method of riding is running it dry on the main tank, switching to reserve and heading to the next station.

If I yank the petcocks out, is this something I can fix? Would I need to fish the reserve pipes out of the tank? What if they're not in the tank? Should I buy alternative petcock(s)?

I located the owner before the last owner (turns out he's my bicycle mechanic) and he said he always just filled the tank around 100 miles and didn't know anything about it having no reserve. Having a half gallon or more fuel in reserve just makes me ride more comfortably. What do you guys think?

 

[jd750ace]

If the main stand pipe has fell off, rotted off, or is otherwise not there, it'll run to empty. If it has 2 petcocks, check them both. It only takes one messed up to mess you up if it still has the common feed setup where both flow into a crossover tube.

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[XSLeo]

With one petcock turned on, the other off you will have a partial reserve. Not all the fuel in the tank can drain from just one side.
Your 77 has a 3.9 gallon tank. If your petcocks worked right and you turn them both on you will have about .9 gallon reserve.
About half that if run one petcock till it quits then turn the other petcock on.
I kinda do that on my 75. Run with just one petcock on for one tank full then run the other on the next tank.
The petcocks are easy to remove, drain the tank, pull the screws and they should pop right off.
The stock petcocks had a brass tube about 1 1/2 inches long. If they are corroded away, you might be able the drill out the holes where they went, get some new copper or brass tubing and "glue" them back in. A fuel resistant "glue" should work fine. I might reccommend Seal's All, It comes in a red and yellow tube. It can even seal a hole with fuel running out of it.
If your petcocks are beyond repair new ones can be gotten. Mike's XS has them.
On a road trip if your bike gets reasonable mileage you can run out to about 150 miles before you hit reserve. Most well tuned XS650's without severe mods get 50+ mpg. If I hold my speed to a steady 50 mph I get about 55 mpg. Run it faster and the mpg's drop a bit. 60 gets around 50, 80 gets about 40.
Leo

 

[daoist]

I don't think mine gets very good mileage. On a recent trip from Tucson to Bisbee, I think I was getting in the 30s. But I'll admit I was just eyeballing the trip odometer and doing the math in my head, so hopefully I'm wrong. I guess I'll have to pop those petcocks off and have a peek...

 

[tnicean]

I had the same problem. The pickup pipes were split all the way down, so it would use all the gas in the tank. I replaced the petcocks. Problem solved.
Tnicean

 

[gggGary]

Yes the stand pipes tend to split the long way. Sometimes they rot off at the base. Most guys won't attempt a fix. I have cleaned, wrapped with some fine copper wire (some strands from auto wire) and soldered the crack shut. But if you aren't careful the tube gets too big to fit through the hole in the tank. Really it deserves new petcocks. It just isn't worth the risk of using old worn out crap petcocks and filling the crank with gas.

 

[rbjenterprises]

Make sure that you put the petcock levers back in the correct positions. There is a very small L and R cast in to them. Wrong sides will work but reserve and on will be reversed.

 

[XS650DL]

Make sure that you put the petcock levers back in the correct positions. There is a very small L and R cast in to them. Wrong sides will work but reserve and on will be reversed.

Yeah, I found that out the hard way. My petcock "handles" were on the wrong sides so
I ran out of gas with the handles in the down position. Like you said, they were really
on reserve.