Fuel starvation

[Butters]

After removing the redundant fuel pump on my Skorp I now have what I think is a fuel problem. Under load at high RPM, 6000 plus, it coughs, bangs and dies until I back off the throttle. I have blanked off the vacuum tube. Any ideas where I should start looking?

[Bill Jurgenson]

the fuel pump is as useful as a fifth wheel. Serious dealers in Europe removed it before selling the bike.
none of mine had one, least of all the racer which never had starvation problems although it was almost never run as slow as 6000 but often over 9000.
check the tank vent.
this is at best marginal and is notorious for clogging due to oxidation of the aluminum fitting.
I know this from personal experience and use a standard plastic tube on top of the tank.
then the petcock itself which is simply not big enough. Skorpion Cup racers must run stock but they do drill out the petcock as far as possible.
check the catch sieve of the petcock as well as that of the carburetor below the float valve.
I replaced the petcock with a 1/4" ID quickrelease fitting which also makes tank removal a lot easier.

[arry_b]

Check the simple things first.

Check you've not got a kink in the fuel pipe between the tap and the carb. I caught myself out when I removed the fuel pump from mine, and had exactly the same symptoms as you've got now.

[Butters]

Well, petcock filter clean but somewhat distorted. Fuel line did have a kink. Have swivelled the inlet spigot to give it a straight run.
Fun bit is the breather. Cap section is fine. No corrosion and seals good. However, the hole in the tank is full of water. I've poked copper wire from both ends to no avail. The rubber pipe is fine. not trapped or kinked. What on earth has got in there?

[DAVID THOMPSON]

it may have been that way when made
or
THE BEE'S
we call MUD DAUBERS in the usa
sharpen your wire to look like a flat screwdriver and spin it slow to cut the mud out
dave

[Butters]

Took seat & side panel off to get at the ally tank fitting. Once the tube was removed I found a mass of corrosion. Blocked solid. Will clean up & run a drill through. Many thanks to you guys for some great help, as ever.