Petcock problem? Not sure...

[CocoaFL_Valkrider]

Hello all....I have a 99 Valk with 124K miles. Over the past year or so, I've encountered a "problem" where the bike acts and sounds like its running out of gas but before its ready to switch to reserve, but sometimes it happens only 50 miles into a fresh tank. I switch to reserve and then back after a minute or so on reserve and the phenomenon goes away. More often than not, this occurs with two "bars" on the fuel gauge but as of late, it's happened with almost a full tank....any ideas on what gives here? It happens with 83 octane ethanol as well as regular leaded "recreational" fuel.

TIA, John

[Daniel Meyer]

Check the tank vent hose for obstruction/kinks.

But yes, do a vacuum test on the petcock, and rebuild if required.

[longrider]

This is a classic petcock symptom.  Install the rebuild kit and you'll be good.  Be gentle when assembling the new diaphragm.  Part is cover set  16953 MBz b51

[The emperor has no clothes]

Something else to consider. I have a raised tank because of the velocity stacks. Also have the chrome engine covers. Because of that the petcock switch can get in a slight bind and not have a correct setting. Make sure the switch is lined up correctly. When mine wasn't I had symptoms identical to yours.

[nogrey]

Pretty common problem and agree with above posts with few exceptions. It won't be your vent line because a pinched line inhibits the replenishment of air in the tank as the fuel is used. Switching from "on" to "res" would do nothing to illeviate that problem. Your bike is 18 years old. Any original rubber on these bikes is due for replacement. All vacuum lines, belts, and seals in carbs are prone to failure. Petcock is a given after all the years and gallons of fuel delivered through it. Another overlooked item is the fuel strainer that sits over the petcock stem. Often times it does not come out with the petcock and is therefore not seen. The strainer in your bike, if original, is deformed and possibly clogged in such a way as to restrict full flow of fuel when the petcock is switched to the "On" position. Switching it to "Res" opens a port lower on the stem and thus a new entry for fuel to flow through. I would recommend buying the "cover kit" mentioned above and rebuilding the petcock, as well as removing, cleaning and possibly replacing the fuel strainer that sits on the petcock.

[CocoaFL_Valkrider]

Thanks to all of you for your replies...sorry I'm late in getting this out....had to go out of town unexpectedly. Your comments and suggestions are all greatly appreciated. Wish I had asked before pulling the tank a few weeks back when replacing the breather filter! Getting ready for a bucket list 8K trip around the country and don't want this looming over us as we head to Sturgis from FL.

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