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Fuel reserve? What reserve?

  • Thread starter Thread starter Anonymous
  • Start date Start date
A

Anonymous

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Folks,

I was under the impression that the fuel valve on my 450 had 3 positions: run (lever toward the rear), prime (lever down), and reserve (lever to the front). I ran out of gas on the way to work this morning. "No problem!" thinks I, "I'll switch to the reserve!"

No start. I walk the mile+ to the gas station, get a can and a gallon of gas, call a buddy to drive me back, put in the gas, still no start. Switch the valve back to run, starts right up.

Is there a trick to using the reserve? Or could it be I have a clog somewhere? The lever is pretty hard to turn. Is this normal?

Also, it appears I got about 150 miles on a full tank. Is this reasonable for an '82 that's in fair shape?

Dave
 
do you have a fuel gauge? if so you may not actually have reserve, but it should still get fuel when in that position.
 
crazyguy said:
do you have a fuel gauge? if so you may not actually have reserve, but it should still get fuel when in that position.
Click to expand...

Nope, no fuel gauge. The valve has RES stamped on the body next to that position.

Dave
 
If the in tank filter is missing it will run until it is dry--- NO reserve
 
It's also possible that your reserve portion of the petcock is clogged up. I believe this happens if you never use it.
 
Sounds like your reserve is clogged....

Take your petcock out (obviously wait till you've got a 1/2 tank of gas or less) & clean the filter...
 
Re: Fuel reserve? What reserve?

Hinermad said:
Folks,

I was under the impression that the fuel valve on my 450 had 3 positions: run (lever toward the rear), prime (lever down), and reserve (lever to the front). I ran out of gas on the way to work this morning. "No problem!" thinks I, "I'll switch to the reserve!"

No start. I walk the mile+ to the gas station, get a can and a gallon of gas, call a buddy to drive me back, put in the gas, still no start. Switch the valve back to run, starts right up.

Is there a trick to using the reserve? Or could it be I have a clog somewhere? The lever is pretty hard to turn. Is this normal?

Also, it appears I got about 150 miles on a full tank. Is this reasonable for an '82 that's in fair shape?

Dave
Click to expand...

You have your petcock positions off... At least on my 82 450, it's lever-front for reserve, lever back for prime, and straight down for RUN.

150 mi/tank (50mpg) is good for an 82 450. I average 45-55 depending on riding style & traffic conditions for that tank (bike likes 55-65mph in 6th for peak milage, it seems)...

Go clean your in-tank filter & petcock, that should get you (RES) back...
 
Re: Fuel reserve? What reserve?

[quote="Dave_A]
You have your petcock positions off... At least on my 82 450, it's lever-front for reserve, lever back for prime, and straight down for RUN.

<snip>

Go clean your in-tank filter & petcock, that should get you (RES) back...[/quote]

As Homer Simpson would say, "D'oh!"

I took a better look at the valve markings and you're right. I've been running on prime all this time. I'll bet prime draws from the reserve, too, right?

I put a whisker less than a gallon in the tank when it ran out this morning and rode it the rest of the way to work. After work I put the valve in the (correct) RUN position. About 5 miles toward home it sputtered off again, but I swung it into RES and it worked again.

Problem solved - thanks!

Dave
 
the petcock only has three position (pri) to the rear, (on)toward the ground, And (res) forward. am I missing something ? which is off?
 
Their is no OFF when you turn the engine off the vacuum valve closes
 
It would be handy if you could post a photo of your petcock. On my 450 petcock (which busted yesterday, leaking a gallon and a half of gas right out the petcock body), there are two positions. Down is run and front is reserve. Vacuum operation is supposed to provide the "off" setting... Anyway, petcocks vary so if we could see it we could tell you how it's supposed to go.

Michael
 
PRIME draws from the same spot as 'RUN', IIRC.

There should be gas sloshing around in the tank if you have any 'reserve' left.

You have been running in 'PRIME' though, which means you also may have gas-in-the-oil problems...

CHECK YOUR OIL
 
Dave_A said:
You have been running in 'PRIME' though, which means you also may have gas-in-the-oil problems...

CHECK YOUR OIL
Click to expand...

It's probably due for an oil change anyway, but how would gas get into the oil?

Dave
 
Hinermad said:
Dave_A said:
You have been running in 'PRIME' though, which means you also may have gas-in-the-oil problems...

CHECK YOUR OIL
Click to expand...

It's probably due for an oil change anyway, but how would gas get into the oil?

Dave
Click to expand...

1, if your needle valves in the carbs are not seating all the way, the pressure form the gas can cause bowl overflow issues.

2, If the petcock is bad, it will leak gas down the vacuum hose and straight in to your intakes, so it can leak down in to the crankcase.


According to my service manual, PRI should take any fuel in the tank, be it from main or reserve.
 
My '80 550L has no reserve, it does haave a gauge though. Two positions and no lever you need a screwdriver to switch between run and prime.
 
Hinermad said:
Dave_A said:
You have been running in 'PRIME' though, which means you also may have gas-in-the-oil problems...

CHECK YOUR OIL
Click to expand...

It's probably due for an oil change anyway, but how would gas get into the oil?

Dave
Click to expand...

On (what seems to be most) old bikes, the carb internals have become 'worn' to the point where they will flow fuel as long as there is fuel pressure... On the GS and most bikes, there is ALLWAYS fuel pressure unless the petcock is closed (either manually or automatically), as a gravity-feed fuel system is used.

The extra fuel flow isn't enough to affect operation, since it's usually less than the burn rate, HOWEVER it poses problems when the bike is let to sit and the extra fuel is not burned off (eg when you park for the night).

This is why bikes with 'manual' petcocks have an 'OFF' position. In the case of the GS, there is no 'OFF' because the designers (quite wisely, given how many people treat their bikes like cars and expect to be able to turn off the key and park it) designed it to automatically shut off when there's no engine vacuum.

Now, if your bike is left to sit, and (like most) the carbs flow fuel while there is pressure, there are only 3 places for that fuel to go: Out the vent tubes, into the airbox, or into the cylinders. Now, the vent tubes are mounted high (as their primary function is to allow air into the float bowls so the carbs operate properly), so it takes ALOT of gas to cause flow out the vents, and generally when this happens, gas is going to one or both of the other 2 spots.

Now, the part that referrs to oil. If your bike is parked with the carbs level or nose-down (eg when it's parked anywhere except nose-up on a steep hill), the gas will flow into the cylinders. Since the rings don't seal tight with the engine not running, this gas runs down past the rings and into the oil.

GAS IN THE OIL IS BAD NEWS -> it (a) thins the oil, and (b) displaces it away from moving parts, removing lube... If this is the case, you will basically be running your engine with Kerosene instead of motor oil...
 
jimcor said:
My '80 550L has no reserve, it does haave a gauge though. Two positions and no lever you need a screwdriver to switch between run and prime.
Click to expand...

That design is on my '80 850... It's a terrible petcock design...

The '82 design that he has (which is also on my 82 450TX) is MUCH better.
 
Dave_A said:
Now, the part that referrs to oil. If your bike is parked with the carbs level or nose-down (eg when it's parked anywhere except nose-up on a steep hill), the gas will flow into the cylinders. Since the rings don't seal tight with the engine not running, this gas runs down past the rings and into the oil.

GAS IN THE OIL IS BAD NEWS -> it (a) thins the oil, and (b) displaces it away from moving parts, removing lube... If this is the case, you will basically be running your engine with Kerosene instead of motor oil...
Click to expand...

You've convinced me. I've already replaced one engine this year (Pontiac minivan - intake manifold gasket failed, allowing coolant into the oil.). I'm not up for doing it again.

Thanks!

Dave
 
well, I see you've realized the problem, but I wanted to mention that MY bike doesn't work on this basis
PRIME draws from the same spot as 'RUN', IIRC
Click to expand...

my prime comes from res, and when I had it all apart, the holes match up to back that up...

disclaimer, many bikes are different so I ain't sayin anyone's wrong, just if you have a GS650G from 1981 :wink:
 
My '80 GS750L also has no reserve and no lever. I don't know which direction to turn the screw for prime or on. I changed my oil yesterday and I already have fuel in the oil which is noticable by smell (very strong) and my level is above the max in the little window.
 
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