Installing petcocks

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Jul 18, 2005
I have my tank off and cleaned up, now ready to install a new gas cap and petcocks. Any potential problems I should be aware of? Should I use teflon tape on the petcock threads? I ask because when I cleaned out the tank there was a lot of old teflon tape that I presume came off the threads the last time they were installed. Thanks in advance for any comments. feliz
I'm going to reply to my own post with another question. I there a "correct" side of the tank to install the reserve petcock, that is, the petcock with no tube? Thanks.
Jason Curtiss said:

No Teflon tape is required if you use the rubber impregnated sealing washers.


Mmmmm. The washers the supplier sent are copper washers, flat on one side and rounded on the other.
The copper washers will probably leak. I assume that is why peopale use the tape. I can imagine the modern fuels eat up the exposed tape in the tank and make a mess.

The rubber impregnated washer is an upgraded washer, definitely the hot set up.

I recommend the rubber impreg washer.

Which side for the reserve stirs up debate. Most Commandos came with the reserve on the right. This requires taking hand off of throttle to operate. A lot of people like to have the reserve on the left to alleviate this.
If you decide to use Teflon tape, start the tape two threads back from the end of the threads on the petcock. This will prevent the tape from becoming cut and separated upon installation of the petcock to the tank.

Thanks loads for the responses, very helpful.

OK, I went and looked at the washers and they are in fact rubber with what looks like a thin copper coating on three sides, the bare rubber is on the inside. I just took a quick look when I opened the box and saw what looked like brass washers. Thanks again.
petcock washers


What you decribe sounds like crush washers used for oil plugs. These might work, but aren't intended for the petcocks. The neoprene (rubber)/metal washers mentioned are the type used for hydraulic applications. They are the best to use here and smaller versions work well for overhead oil line attachment to the head. You can order these from many Norton parts sources.

What you decribe sounds like crush washers used for oil plugs. These might work, but aren't intended for the petcocks.

What Feliz has described
rubber with what looks like a thin copper coating on three sides, the bare rubber is on the inside.
would seem to be the correct 06-5329 sealing washer.
I use those neoprene/copper washers that David mentioned and they don't leak! I think they're called Dowty washers? (Not sure about the spelling). Anyway, they do work. And I did not need the teflon tape.

I use a reserve petock (no standpipe) on each side. I find it more convenient to use the left side for reserve but not everyone agrees with me. Some people have strong opinions about this!

Ask ten different Norton owners, get ten different answers...

"I think the Norton type are similar to the Stat-O-Seal"

Actually my '73 came from the dealer with fiber washers (P/N 000183) under the petcocks. I think the Dowty and Stat-O-Seal idea came from the dealers and not Norton. I replaced the fiber washers with the Stat-o-Seal type after about six months of ownership on the advice of my dealer.
I'm not sure exactly when Norton started fitting the Stat-O-Seal washer, ('73 parts book lists the 000183 washer) the 850 Mk3 parts book lists the part as 06-5329 and the parts illustrations seem to show them as a Stat-O-Seal type washer.
Thanks again for all the responses.

The washers I received from the supplier in Canada, a large British bike parts outlet, are part number 62302/A washer,rubber/rubber,tap. They are copper on three sides, filled with rubber with the rubber contacting the threads, when crushed the rubber would squeeze into the threads forming a seal.

I can't find it in any of the Norton parts books but it may be another Brit bike part.

It looks to me like some sort of crush washer as it's quite thick, I won't use them as I'm afraid the force required to crush the washer hence making the seal could pull the tap out of the tank.

I went to a Kawasaki dealer today and picked up two of the Stat-O-Seal washers some posters mentioned and are shown in the link supplied by one poster. They said they aren't used on any Kawasaki bikes but had them is stock from working on "odd ball bikes" to quote the dealer.

Again, thanks for all the informative posts.
I used the cheesy fiber washers that came with the petcok - one side leaked, a dab of Permatex #2 on the threads did the trick. I did both sides for good measure. I don't know how long it will last.

Thanks for the washer info & merry x-mas to all.
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