If you run a vacuum operated petcock MC out of gas , it is a process to get it going.
Not a big one, but on the side of the road it would suck.
Esp if one did not know it takes vacuum to get the engine gas............and it takes a running engine to accomplish that!
It becomes a circle
Next- I dont work on HD anymore, just my own,
But the outfit i buy parts from says they are probelmatic.

 

When my VOES hose split my bike ran like a real b1tch and it was difficult to ride it home. While I agree about swapping the vacuum gas-tap for a 'normal' one, having a working VOES is pretty essential IMHO, unless using an ignition system that doesn't need one.

 

I went ahead and unplugged the VOES since I couldn't use it and ran a new vacuum hose from the petcock to the carb.

Instantly the bike idled a *LOT* slower and the enrichener was almost useless. I had to bring the rpm's up quite a bit.

Once the bike was warmed up, it would idle halfway decently, and it ran well enough, and I guess it'll work until I can afford another VOES. When I parked it after riding it a bit to test it out, the engine 'ran on' for a second or two when I turned it off, but that's happened before a few times in the past two years and I'm not too worried about it...it's not as much of a problem as backfiring or carb cough would be.

But yes, the VOES does make quite a bit of difference and I have to admit I think I like it over running straight from the tank (no VOES). Plus, I'm too poor to worry about losing much mpg's, I depend on the 45+ mpg's I normally get to let me get what I need done during the month and to allow me to get out of the house for fun once in a while also the same month, heh.

Thanks everyone, for all the advice though. It's good to know.

OH! I found in my H-D service manual that this FXD ('97-'98) has a VOES of 3.5-4.5 inches, so I'll order a new one with 5 inches as if I read about that stuff correctly it might help a little with my big self on the bike and carrying anything also. Does that make sense or did I get it all backwrds and should be getting a VOES with 3 inches?

 

"OH! I found in my H-D service manual that this FXD ('97-'98) has a VOES of 3.5-4.5 inches, so I'll order a new one with 5 inches as if I read about that stuff correctly it might help a little with my big self on the bike and carrying anything also. Does that make sense or did I get it all backwrds and should be getting a VOES with 3 inches?"

Go with stock or slightly higher. Don't go less. Remember, if you have a hand vacuum pump and a meter, the VOES can be adjusted.

The engine "run on" usually indicates your fuel mixture is lean.

You can also modify the vacuum type fuel petcock so vacuum is no longer needed in order to make it flow by moving the diaphragm spring to the other side of the diaphragm. YD

 

Alternatively ignition timing is out.

tar_snake, 'run on' is a symptom of a hot-spot in the cylinder, which is not good. Could be the spark plug(s) or a valve and should not be ignored, nor lived with! If you're poor then fix it ASAP, or it may make you poorer still.....

 

5-6"of vacuum is for lighter bikes. Just stick with the one for your bike.

And as Graham said if your having run on, it could be several things. High lean idle on a hot motor or to much timing. Do you have an inductive timing light to set the timing? Autozone has them. You put money down to rent them and when you bring it back you get all your money back.. It's free, if you return the tool.. I keep my idle between 900-940 rpm's....

Also I Don't think I would flip the spring in the petcock. What I've done in the past is remove the diaghram and spring and make a plate and gasket. It'll free flow no problem. Just turn off your fuel when not riding.

 

Okay, I'll snag a 4 inch VOES and keep it pretty much stock.

I've got a decent timing light (an Innova 3568), and have everything I need for changing my cam (and the bearing and the lifters now too, and S&S quickee pushrods). I figure if I can hold off on any riding until next month (except for the doc appointment), I'll get the VOES and put it and the new cam in all at one time.

The bitch about that is, with the pain I'm always in, this kind of job always takes me two or three times as long as normal to get done and then I have to double-up on my pain meds after for the next day, lol.

Thanks for the heads up about the run on. Could the A/F mixture get off by removing the VOES? If it was 2 and a half turns out *with* the VOES and it ran perfect, removing the VOES and just running the vacumm line from the petcock to the carb, could it change the A/F needs like it did the idle speed?

 

Yes it actually can. You might be turning it in just a tad...

 

You mean turn it out a little, to get its richness back to like it was *with* the VOES?

 

The VOES is ignition timing specific, not carb, so AFAIK while the VOES uses manifold vacuum it doesn't have any significant affect on fuelling. Sort out your VOES, then make suitable adjustments to ignition and carb settings. By all means have a tinker, but don't expect to cure one problem by creating another!