Karcoma blues

[Unclviny]

1973 R75/5:
Saturday night I was riding home and the R75/5 was running fine but when I let it idle-down it would just idle-down to nothing, I felt like it was starved for fuel.
I looked today and the right Petcock flows like it should but the left lets a drop through about every 4 seconds! (I had a school for work for the last 3 days) so today I drained the full-tank and removed the left Petcock which appears to be packed (almost) solid with tank-liner, I can't get (very much) air or water through the thing.
There are no rebuild kits in town and I need the bike saturday, luckily there is a new Petcock on the shelf at my local-BMW-dealer.
I love my Bavarian Money Waster sometimes!, the tank has been "shedding" liner for a while now so this wasn't a complete surprise.

Vince

[dougie]

so this wasn't a complete surprise.
Vince

Back at the factory they would say it was your fault.
Nasty buggers.

[mattcfish]

Strange... My highly modified /6 will run just fine on 1 pet cock, even at full throttle.
A clogged petcock is a problem to fix, but it shouldn't effect idle if the other one is flowing.

[Duane Ausherman]

One petcock isn't enough flow under certain conditions. Besides, it is risky, so why allow it. Always assure full fuel flow through both petcocks.

[ME 109]

I've never experienced an issue with running on one petcock, even wot in 5th on long straights.
It's hard enough remembering to turn off one fuel tap, let alone two.

[SteveD]

I've never experienced an issue with running on one petcock, even wot in 5th on long straights.
It's hard enough remembering to turn off one fuel tap, let alone two.

Same here.
Unc, would some compressed air thru the tap clear it?

[Duane Ausherman]

Yes Steve, that is for emergencys only, as it is temporary.

Our race bike woulnd't even run to top speed with both petcocks on and a low fuel level. The petcocks can become your main jets and that isn't good.

[Unclviny]

I tried clearing it with air, water and shock and the tank-liner-bits seem to be keyed in there very-well. I went to my local dealer this morning and he had them on the shelf (they are 90 degree outlets so I got both-sides), $83.00.
I have the bike sitting in the sun with both Petcocks off and the cap open, my plan is to wipe-out the inside with a curved-rod with a small towel taped on the end to get the loose-stuff off and blow the tank out with an air compressor and a blowgun.

Vince

[Duane Ausherman]

Remove the tank, insert many nuts and bolts, shake well and clean out.

[dougie]

Remove the tank, insert many nuts and bolts, shake well and clean out.

+1.
I also did varsol, soap and water, and sunshine after the nuts and bolts.
You could also consider POR-15, but that's a big job. (Ain't done it yet.)