Fuel line petcocks

[Cappy]

Any advice on the removal and replacement of the fuel petcocks on older fiberglass tank models ('73-'76)?  I can not ssem to get the 16mm nut off the threads protruding from the tank.  In fact it seems as though the whole threaded portion is rotating when I attempt to loosen the nut.  Any ideas, suggestions or comments to help would be most appeciated.
Thanks,


1974 KTM 175 Jackpiner(restoring to good health...slowly)

[tomale]

HI cappy,
This does not sound good. hopefully the threaded tube in the tank is not turning, that would not be good and difficult to fix. Do you realize that the threads are left handed? If you try to turn the wrong way and use brute strength you could loosen the treaded tube in the tank. You do not want to do that. With the tank in the upright position, try carfully turning the nut to the right (like you are tightening it). go slow and easy. if you have loosened the treaded tube you will have to secure it again before the tank can be used. By the way if it is loose the tank will leak. If the newer formula gas has sit in it for very long it will eat at the fiberglass not a good think either. make sure that you empty your tank after each time you ride. I believe that there are some sealants on the market but someone else will have to help you with that. Good luck.
I am glad that you asked the question it shows good sense. It is better to ask before you do than to just bull yourself through it. your assumptions about something could be wrong and you could ruin it. There are not many left handed treads on your bike but this is one of them. The other one is the nut that holds the mag on. There may be more but I can not think of it right now.
let us know how it goes.

Thom Green,I own and ride a 76 250 MC5 MX which I bought new.

[Cappy]

Thom,
GREAT info...you may have just saved me from making a mess of things!  I will check closer but I think the tank threads are turning with the nut regardless of direction (not a good sign).  I appreciate your advice...thanks.
Regards,
John

'74 Jackpiner (running)
'73 Jackpiner (on the garage floor)
'74 CZ Enduro (in storage)

[Rocket]

Lefty loosey, righty tighty.  The nut screws onto the tank with right hand threads, clockwise, and it screws onto the petcock with left hand threads, counterclockwise.
Good luck
Rocket

[firstturn]

Rocket,
  You left yourself wide open on this Lefty Righty, but being the gentleman I am I will let the Poet from(Western) Illinois off easy[)].

The Steer from Texas,

Ron Carbaugh

[tomale]

I stand corrected. I was confused by the fact that the threads on the petcock are left handed. but the threads on the tank are right. To loosen The petcock, as Rocket has said so well, they are removed like a standard threaded nut... I just went out and checked... Please forgive my oversight. Why they do this..hmmm.. well as best as I can figure it is so that the petcock can be positioned correctly. If any one has more insight I would be interested. Any of you guys know how to hold the threaded tube in the tank from turning? I would be interested... just for future reference. It sounds like the kind of thing that can happen but no one wants to happen. The stuff of nighmares. again please forgive the upstart.

Thom Green,I own and ride a 76 250 MC5 MX which I bought new.

[wildman]

I just got done repairing my 1975 250's gas tank with this problem and it wasn't easy. Actually, not only did the tank fitting spin it was cracked at the flange where it entered the tank. I took a 1* flat spade bit and sharpened the backside or top of the blade towards the shank that goes into the drill motor. Then I could drop the shank through the gas fitting, hook it to the drill and carefully reverse drill the inside of the fiberglass just enough to free the petcock fitting. My fitting was cracked so I  rebrazed it then sandblasted it clean. I reached into the tank and sandblasted with a long tube inside the tank around the fitting area to rough up the surface. Wash the tank out with acetone 2 or 3 times until it flushes clear and don,t get it on any paint you want to save. Find a West Marine store and get a fiberglass repair pack, it has 6 individual packs of 2 part epoxy (205?), mixing cups,additives,everything you need.$20 Mix a batch, cover the fitting and the inside tank area, then drop the fitting in on a coathanger to guide it. I took one of the brushes provided and extended it on a wire that I could bend to reach inside. Slab epoxy over the fitting inside and let it set. It gets on everything you touch so be ready.I did mine this winter and it took almost a day to really set up @50 degrees. BTW, I also resealed the filler neck,it leaked before and some suspicious cracks near the rear I did also. It sounds like an extreme amount of work, but with a little brainsweat, a custom ground $3 drill bit and a fiberglass kit, I saved my original tank for about $25 and some cold winter days. I'll help guide if I can, hope this helps. Wildman

1975 250 Cross Country, 1974 175 Jackpiner, 1975 125

[Cappy]

I love this forum...you guys are GREAT!  I think I have some work ahead but nothing that I can't handle over the next few months.  Thanks again to all of you who replied and for all the tips and information.
Regards,
John

'74 Jackpiner (running)
'73 Jackpiner (on the garage floor)
'74 CZ Enduro (in storage)