Does anyone know what the threads on the Chrome Tanks
are on the fuel cocks. I thought it looked like a M10 X 1.0
but I am not sure. I need to make plugs to seal up the tank
for cleaning. (Wombat 125)
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dirtsquirt74 - 04/19/07 at 1:39pm
I had the same question a few years ago.
Took the petcock down to the parts house looking for a plug for the tank. I was told that the petcock had machined threads and they had nothing that would work. Thinking it was a .09 thread pitch.
Good luck
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Bullfrog - 04/19/07 at 2:32pm
I researched this a couple years back . . . but can't find the notes right now.
I do remember that the petcock threads are not metric.
Some ancient 3/8" X ?? thread pattern was identified.
Sorry I can't be of more assistance right now.
Ed
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gregg_floren - 04/19/07 at 3:03pm
I THINK they are a standard pipe thread. I had a Chrome Tank Dirt Squirt where somebody had replaced the petcocks with standard pipe valves. When I pulled them out, a set of new stock petcocks threaded right in.
Maybe try some brass pipe fittings for plugs. I think they'll fit and the brass is softer than the steel. If any threads get damaged it should be the on the plugs, not the tank
Gregg
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hodakaronwa - 04/20/07 at 1:45pm
Note:
The petcock threads on the crome tanks are a metric straight pipe thread. They have no taper to them as a standard U.S. pipe thread. They rely on the fiber washer to seal and not the taper of two matching tapered threads to do the sealing.
Yes! I have seen some tanks where someone has gotten lucky with the use of a 1/8" U.S. pipe thread installed. Now there is a U.S. straight pipe thread which is close but no cigar. It may be possible to work the straight U.S. pipe threads into the hodaka tank threads. I have also seen some petcocks used which were sold through Go-Kart shops that I have been told that they work. I have not tried but possibly a 1/8" U.S. pipe tap could be used to change the threads to the US tapered thread.
Or? Possibly you could go to your local machine shop supply and purchase a straight metric pipe DIE to convert your petcocks which you would like to use?
It's all in how much time and energy you want to invest. Strictly Hodaka sells the new Chrome tank style petcocks which for me have worked out just fine.
USE small rubber stoppers or corks for cleaning.
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Rick - 04/20/07 at 1:57pm
I just went to the local hardware store and got two tapered rubber stoppers. Worked fine. Just twist them in and twist them out. They hold real well and don't shake out or leak.
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patti - 04/20/07 at 6:30pm
Guys good morning or maybe afternoon now. From memory I believe the petcock threads are a 3/8 # 28 pitch. Roger would know for sure as I believe he did you out and buy a tap at one time. We spent a lot of time chasing this one. I hope this may help someone down the road.
Going diving on the Great Barrier reef in a few minutes. Australia is already fantastic and we have not yet met up with Ken or the rest of the gang.
Paul
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joebat - 04/20/07 at 10:58pm
If it is a U.S. 1/8 pipe size then the pitch is 27. U.S. Pipe threads do come in taper (NPT) and Straight but a 1/8 would be 27 TPI.
From a machine guy...
SmileyJoe
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patti - 04/21/07 at 4:33am
Joe you are probably correct. I thought that we had tried a #27 and that was a bit off and we had to go to a #28. I have the correct information listed on my computor at home.
Thanks for your help.
Paul
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Scooterpimp - 04/21/07 at 8:02pm
1/8" x 27 BSP( British Standard Pipe) Is The Proper Petcock Thread. Most Good Quality Metric Tap & Die Sets Include This Size Tap & Die.
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FXHODA - 04/25/07 at 5:02pm
I think that I have solved the puzzle of the fuel thingy thread.
The following is from The Machinery’s Handbook
British Standard Pipe Threads BS 2779 1/8”-28 TPI (Metric Equiv. pitch is 0.907)
The Thread is for Non-Pressure Tight Joints.
A similar thread is tapered (like our standard NPT thread) for sealing on the Thread
(not with a gasket or o-ring) The common name is BSPP which stands for
British Standard Pipe Parallel. The Thread form is Whitworth. (if you can believe that)
Whitworth form parallel fastening threads that are generally used for fastening
Purposes such as the mechanical assembly of component parts of fittings, cocks
(as in Hodaka Fuel Cocks) and valves. They are not suitable where pressure-tight seals
are required on the threads. The seal is by gasket or o-ring. There is some more info and
links @ http://en.wikipedia.org/wiki/British_st ... ipe_thread.
I purchased some of these plugs from McMaster Carr and they fit perfectly.
The part # 4860K125 @ $2.40 each
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END OF THREAD