Petcocks ?

That nice transition from ON to RES when riding is directly related to the clean good flow of the petcock, what fuel filter is used and maybe most important the routing of the fuel line to the carbs. These things can be DRASTICLY different from one bike to another bike. In the situation of no fuel after switching to reserve....remove the fuel cap and blow into the tank, don't inhale, that will make you stupid, just a little pressure will make the fuel flow. Better yet, clean the tank and petcock and re-rout the fuel filter and fuel lines for a better transition from ON to RES.

Smaller fuel filters usually flow better than larger ones.

Scott

Well, another take on the "reserve" question.

Madmax, with your new acquisition, you'll be taking a small step backwards in motorcycle technology. Your previous bikes probably had filtered standpipes. Not sure about the petcocks on your XS650, but on the older petcocks, there were no filters. Just brass tubes.


Fuel flow from those 2 standpipes goes directly into the valving, then onward to the rear cavity where the screen filter exists. The petcock's "whizzer valve" is a round 4-hole rubber gasket, against which the selector lever rotates.


Working in bike shops in the '70s, I replaced many whizzer valves, mostly on period Hondas. Again, before standpipe filters were used. The upper "on" standpipe picks up clean fuel, but the lower "reserve" standpipe gets the grunge at the bottom.

The grunge can chew up the whizzer valve, like this:


Things like these experiences go thru my head when switching to "reserve".

madmax-im said:

...You have some neat gauges..What are you monitoring with the PSI gauges?

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madmax-im said:

A real freakin gas gauge..i'm impressed..i would love to do that...

Click to expand...

Haha, thanx Madmax.
Yes, and warning, you've entered the lair of the tinkerers, folks that like to do cool mods to these bikes, and there are many. Billions and billions of gold nuggets are buried in this forum.

The 2 pressure gauges are for monitoring oil pressures.

http://www.xs650.com/threads/xs650-top-end-oil-pressure-gauge.45317/

http://www.xs650.com/threads/hp-oil-pump-from-mikes.40991/page-3#post-477090

Here's the gas cap gauge.

http://www.xs650.com/threads/gas-cap-gauge-for-the-early-70-73-tank.51553/

TwoManyXS1Bs said:

Yes, and warning, you've entered the lair of the tinkerers, folks that like to do cool mods to these bikes, and there are many. Billions and billions of gold nuggets are buried in this forum.

Click to expand...

Yeah i know..WTF am I doing here???

madmax-im said:

Yeah i know..WTF am I doing here???

Click to expand...

Learning, having fun and meeting some new buddies....