5 replies [Last post]
Darryl.Richman
Darryl.Richman's picture
 Offline
VBMWMO #6285
Surf City, USA (Santa Cruz, CA)
Joined: 10/27/2006
Posts: 2185

So, my 2014 Cannonball bike, the 1928 R52, is nearly ready to go, and not a minute too soon. I'm leaving next week for the long drive to Florida for the start.

I have one nagging issue I'd really like to solve. The bike has an original petcock on the main tank and a repop petcock on the auxiliary tank. Both work the same way: a brass pintle fits into the brass body and is held in place with a spring, washer and cotter pin. The two main pieces are intended to meet with a taper that, by itself, is supposed to be gas tight. In both cases, the taper fit weeps gas around the pintle when closed. (It's not an issue when open as the bike takes enough gas that it doesn't seem to leak then.)

I have tried:

  • The repop item came with a dab of fine grinding compound. Actually, I bought two of these petcocks, and I ground out enough of the pintle that it sits at least a mm closer in now.
  • After that, I thought I needed something finer, so I tried toothpaste.
  • I thought that maybe some kind of sealer would work. I tried Hylomar, which never sets, and Yamabond, which does.
  • I have added more washers to the stack, to increase the spring pressure holding the two pieces together.

Does anyone have a (useful) suggestion for me?

__________________

VBMWMO Webmaster,--Darryl Richman
http://darryl.crafty-fox.com

schrader7032
schrader7032's picture
 Offline
VBMWMO #7032
San Antonio, TX
Joined: 10/27/2006
Posts: 6421
My (useful) suggestion is to

My (useful) suggestion is to call Vech!

__________________

Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

brown3459
brown3459's picture
 Offline
VBMWMO #3459
Joined: 10/27/2006
Posts: 74
my experience with early

my experience with early American bikes that use the same type of tapered mating pieces both of brass is that you will never succeed in lapping them so they will seal 100% all the time.
also want to wish you the best of luck in the Cannonball

__________________

Barry Brown
Canada

Darryl.Richman
Darryl.Richman's picture
 Offline
VBMWMO #6285
Surf City, USA (Santa Cruz, CA)
Joined: 10/27/2006
Posts: 2185
You're not the first person

You're not the first person to tell me that, brown3459. Mostly, I would like to get it so that my garage does not absolutely reek of gasoline and the fuel lines aren't soaked and it doesn't leave stains on the castings...

On another list someone suggested lapping in with Brasso, which seems to be even finer than the compound I got with my repop petcocks. Using this, I have gotten my original petcock, at least for the moment, to seal well enough that I can't detect any wetness with my finger. Hopefully I can get one of the repops to seal this well.

__________________

VBMWMO Webmaster,--Darryl Richman
http://darryl.crafty-fox.com

Ian R11
Ian R11's picture
 Offline
VBMWMO #8148
Yorkshire uk
Joined: 10/22/2011
Posts: 199
Use a later tap?

I also tried the methods you described to attempt a seal on the repop taps including oil for final lapping. I was told oil should be used for final lapping but nothing stopped the weep so I fitted the later reproduction type similar to the one fitted to my R11. It has a filter and reserve, but most important…. my garage doesn’t smell of petrol. Does your R12 have one you could borrow?
A simple brass plunger tap works well on the auxiliary tank. I would choose practicality before originality for the event. Good luck.

  • img_0591.jpg
  • img_0612.jpg
  • img_0143.jpg
bmwmyplace
bmwmyplace's picture
 Offline
Australia
Joined: 02/26/2007
Posts: 168
Darryl just saw your post,

Darryl just saw your post, your on the right track, a friend had the same problem on his 1926 AJS in the end he fixed by assembling it wit a little silicone grease , give it a try cheers Peter

Comment viewing options

Select your preferred way to display the comments and click "Save settings" to activate your changes.