Untraceable machine screw. URGENT

[NickyRudolph]

I am having the most difficult time finding the 3 machine screws that go into the petcock. Parts manual says m5. That doesn't seem to fit. A Local fastener retailer is telling me #12-28x1". Please help. Can't get running without it. Only thing left holding me back

[Spokes]

Those petcock screws are the rarest of the rare. Usually they are wasted when found on old tanks.

What you can do is get a M5 tap and matching new screws. Carefully chase the threads in the tank with the tap (use oil on the tap).

Then use your new screws.
BTW, I looked in my many part drawers. I don't have even one..

[Roberd42]

I have a couple, message me your address and I can drop one in the mail. I think I only have two though. I think the heads are ok. I bought a couple lots on eBay a while back. I'll dig in those.

You may be quicker and easier to take chips advice. I had to use an impact screwdriver to break these loose. One I had to drill out (that's why I don't have 3)

[Nige1100s]

I had this problem. They are m5 x 0.9mm thread. This was the Japanese industry standard up to about 1968 when they changed to m5 x 0.8 which Honda wrongly list as a replacement. There is a UK thread called 1 BA which I ended up using. The are used in Amal twist grips used on most Brit Bikes. I have also seen m5 x 0.9 used on modern Chinese scooters so you might have some luck there.

[Nige1100s]

Just found these

http://pages.ebay.com/link/?nav=item.vi ... ID=EBAY-GB

[NickyRudolph]

I think I might just go ahead and drill it to a m5 thats current. Might be more beneficial for the future anyway. Thanks for the help and offers

[grubsie]

This was the Japanese industry standard up to about 1968 when they changed

Same goes for the emblem screws on the gas tank, the starter cover on the right side of the engine and the screws for the controls on the handlebars (lights/horn and start button/throttle)

Oh and also the the upper rear shock nuts.

May be more but I can't remember.

[ByTheLake]

I experienced the same thing a few years ago, so I thought I'd post a link:

http://www.fourwheelforum.com/showthread.php?t=1836&highlight=thread

There was a switch from the JIS to the ISO standard threads in 1967, which affected the 3, 4, 5 and 12mm sizes. Check out the link above for details.

With my CA95 petcock threads, I simply drilled and re-tapped for 6mm threads and it's been great.

[NickyRudolph]

Now, i can tap from the .9 m5 to a .8? Or should I go up a measurement to the next biggest metric screw?

[ByTheLake]

Now, i can tap from the .9 m5 to a .8? Or should I go up a measurement to the next biggest metric screw?

I wouldn't recommend retapping M5 JIS threads with M5 ISO threads. The difference in thread pitch would result in overlapping and weaker threads.

It's quite easy to drill out the old threads and re-tap with M6. I used a cheap set of metric taps from Harbor Freight and it worked perfectly. If you've tapped threads before you'll find it to be quick work. If this is new to you, check out some YouTube videos on tapping threads for some pointers and examples to make the work easier.

I can't imagine how motorbikes were restored in the days before eBay and YouTube. I recall we'd go to swap meets and exchange parts request cards with smelly guys with beards. I'll take eBay.

[rum-rum]

i to re taped the petcock with the m5 tap with my new aftermarket petcock and it worked great I was afraid to really tighten the Alan bolts and it leaked fuel,so i tightened them real tight and it works great