Going on reserve too soon | GTAMotorcycle.com

Going on reserve too soon

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timtune

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I have a first gen KLR650 and I have an odd problem - it often but not always goes on reserve too soon. Just recently it happened and it only took 9 liters and change to fill it. It's about a 22 liter tank.

I've had the petcock out and there is nothing amiss.

Would you think Kawi had variations on the petcock with some having a taller reserve tube?

Love this bike but what a annoying problem.
 
vacuum petcock
 
Petcocks for all years are pretty much the same BUT there have been known problems with them.
Convert to manual (use one with 22mm bolt centres off the Yamaha Banshee - Winner's Circle sells them), block off the vacuum tube and you're good to go.
 
Nope. I actually blocked off my vacuum and used it like a manual one. Same problem.
 
Would it be worth your time to cut down the tubing?

Otherwise, replace the petcock and keep the old one for spare parts .


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I probably could just cut the pipe. It's wrapped in a plastic filter IIRC but I have an line filter anyway.
 
You are currently running an inline fuel filter too? How old is the inline filter? Maybe it’s slowing the fuel flow as the tank level drops.

Would be a simple test to run a tank without the inline filter and see how it behaves.




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I've had the petcock apart more than once and everything appears fine. I'm curious what difference manual vs vacuum would have on the reserve function
 
Gas tank venting might be blocked and creating a vacuum situation in the tank itself; this vacuum situation may be hindering or stopping fuel delivery as the tank level goes down, and the vacuum level in the tank goes up. ?
 
boyoboy said:
Gas tank venting might be blocked and creating a vacuum situation in the tank itself; this vacuum situation may be hindering or stopping fuel delivery as the tank level goes down, and the vacuum level in the tank goes up.
Click to expand...

EDIT
Combine this ^ with the situation as described in post # 9 and....
I would check for vent blockage and replace the fuel filter - do both as this problem may be a combination of the two.
 
^ you can check for this by simply cracking open the tank gas cap the next time it goes "on reserve too early" ...releasing the vacuum and letting fuel flow again. My guess is the vent has a partial blockage - which would explain why it happens at varying times. At high speed high fuel delivery the partial venting can't keep up and the vacuum builds quickly. At slower speeds - and lower fuel delivery requirements ...the vent has a better chance of keeping up.
 
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Ok so riding to work yesterday at 130 miles (US bike) it's starts to stumble and I switch to reserve. A mile late just for grins I switch back to the on position and it runs fine all the way to work and back home later that day.

As to venting I have had that problem before and believe I resolved it but now I'm tempted to add the tee and some extra line just in case.

The inline filter is the clear type and it looks fine.
 
next time try cracking open the gas cap with the petcock remaining in "on" position; and then you'll know one way or another if its venting. (but replace the filter first.)

filter LOOKS fine? ...its a maintenance item, maybe 20 bucks or so?- just replace it.
 
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The filter's clear. Hence looks FINE. I'll replace it when it doesn't, ie I can actually see some dirt.
 
I didn't even know vacuum petcocks had a reserve. How does that normally work?

Mine is just on when there is vacuum (no reserve). Although it seems to be screwy because it developed a leak where the fuel line connects once and would only leak when the vacuum line was connected even though the bike wasn't running. Never figured out why. Just replaced the clamp on the line to stop the leak.
 
Robbo said:
You are currently running an inline fuel filter too? How old is the inline filter? Maybe it’s slowing the fuel flow as the tank level drops.

Would be a simple test to run a tank without the inline filter and see how it behaves.




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Click to expand...
We have a winner.
I convinced myself it was the petcock because it happened at a certain point in the tank/mileage. Finally determined that when I got to about half tank there was no longer enough "head" or volume of gas to help push the fluid past my constricted but perfectly fine looking filter.
Once again concentrate on the simple stuff.
 
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