Dumb question....

OK....I know this is basic but since all I have are shop manuals and no 'operating' manuals I have been wondering. Which fuel tap to open for normal operation? I am guessing it's the right one (as you sit on the bike) with the left being a reserve. Is this correct? Any reason to run with both taps open?

This is a great forum and I thank all for the usefull information!

According to the Owners Handbook for 1975, (MKIII) the main tap was on the right, reserve on the left.

Previous models had them the other way around however, and of course it's easy to swap them over, as many riders preferred the taps the 'old' way around, so the only way to be completely sure (if they are not marked) is to drain the tank, which is also a good time to remove them and clean both tap filters.

Thanks for the info. Maybe it was not such a dumb question :lol:

Sorry I didn't answer your second question.

So,

Commandos don't generally suffer from fuel starvation running on one tap, - provided there's a reasonable fuel flow.
But take care if you buy modern look-alike taps that have a cylindrical seal inside them, as they often have a poor flow rate (I like to run a 5mm drill through them) the cylindrical seals have been known to turn inside the tap body in use, which certainly can cause fuel starvation.

I like main on the right, reserve on the left, since it's easier to turn on the reserve while operating that way.

When I put mine together, I put the reserve on the right ('73). I like Brian's idea of the reserve tap on the left, so you can switch it on with your hand on the throttle, but I also like the main tap right next to the ignition, sort of a reminder to turn off the tap when you shut the ignition off.

+1 on LABs comment about the Emgo taps. Mine had poor fuel flow, and I found the cylindrical rubber gasket was installed backwards - the right way, the holes line right up with the tap; installed wrong way 'round, the holes only allow about 1/4 flow. I also de-burred the valve, which was scratching and gouging the rubber. I guess $16 doesn't buy much these days.

A couple of Meriden Triumph guys I know run both taps open when going high-speed, and I've found that extended runs over 4500 RPM can lead to a bit of starvation, so I'll switch on the reserve on those rare :roll: occasions.

I've also found that I can can poor fuel delivery when the tank is nearly empty. I guess the fuel pressure is pretty low when its down to the last 1/2 gallon.

Whatever works. The main tap on the left would have an additional benefit for me, as I turn the tap off 1/4 mile or so from home, trying to run the bowls and lines as empty as possible (anal compulsive, MOI...???), and that'd be easier if the tap to be turned off was on the left.

But my main concern is being able to switch on the reserve quickly when needed, so I leave it on the left.

is there any reason to not run both taps open? other then the risk of running out of fuel with no reserves?

IdahoCommando said:

is there any reason to not run both taps open? other then the risk of running out of fuel with no reserves?

Click to expand...

That's the only reason.

Even so, you would still have a pint or so after the reserve ran dry, as the bottom inch on the main side would still have gas. It requires laying the bike over on the right to slosh that last bit to the reserve side.

Don't ask how I know, but it will get you another mile or two :roll: