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I am working on a friend's bike, who's fuel tank is shedding debris and causing carburetor idle trouble.

As it is not in the cards right now to reline the tank, I flushed and vacuumed it out.

His petcocks are missing screens and the straws have been cut short. I went through my parts stash and am putting together some acceptable petcocks for him, with the missing screens and correct length straws.

In going through this, I discovered that our Karcoma petcocks have a secondary screen inside the outfeed fitting. I just thought that many may not know this....and should. Add this screen to your annual tank flushing routine.

I knew that, but only on the straight down nipple version. The later rear facing nipple version (mine anyway) don't have those handy little screens.

Garnet wrote:I knew that, but only on the straight down nipple version. The later rear facing nipple version (mine anyway) don't have those handy little screens.

I think only the angled petcocks are supposed to use the top screens. Not needed on the straight petcocks, and easier to clean without removing the petcock from tank.

So, angled petcocks have the in tank screens only and straight have these?

My spares had both! One everbest and one karcoma (both straight)

Frog wrote:So, angled petcocks have the in tank screens only and straight have these?

My spares had both! One everbest and one karcoma (both straight)

I've run both at the same time too, before I found out about the lower screens. Running both is kind of belt-and-suspenders, but if your tank is shedding major chunks inside it might buy you some time between cleanings.

Germa taps also have a similar screen, but have plastic ends that hold shape better.

#4 here...

No matter how you filter the fuel, check the flow rate when done. It should be about 100 cc in about 15 seconds.

The straight Karcoma on my '79 R65 came with both screens from the factory.

Duane Ausherman wrote:No matter how you filter the fuel, check the flow rate when done. It should be about 100 cc in about 15 seconds.

Will do. I am guessing that it will be fine....at first, but won't be long before it is an issue again.

For a temporary fix out on the road due to crap in the filters reducing the flow, just use a bit of air pressure backwards. It will clog up again soon though. Nothing beats a clean tank and filters.