The Bullet Board

I happened to have my decompressor valve blow out of the head while riding home. Wow that was a bang. On the way out, the decompressor damaged the top three threads. I used this method shown in the graphic from 1955 popular mechanic magazine to clean up the damaged threads, it worked well and I am now back on the road.

Here is the graphic.

Cool trick ! I like it . Turn a spark plug into a spark plug thread chaser.... What did you use a V profile file ?

Mrunderhill1975a wrote: ↑Thu Dec 05, 2019 7:39 pm I happened to have my decompressor valve blow out of the head while riding home. Wow that was a bang. On the way out, the decompressor damaged the top three threads. I used this method shown in the graphic from 1955 popular mechanic magazine to clean up the damaged threads, it worked well and I am now back on the road.

That is definitely cool, but I am dying to know why the blew out of the head?

I used a triangular file to cut the notches, held the plug in a vise. The previous owner had blanked the decompressor hole with a plug. Western Cycle Supply was not yet in business at the time. The decompressor in question was one I picked up from Johnny's Speed and Chrome a few years back. It was a decompressor that I believe was for a vintage Triumph or BSA. I did not realize it, but, the thread length was considerably shorter on this decompressor than was a stock RE decompressor. Apparently, it was only long enough to engage 3 or 4 threads. Vibration caused the decompressor to back off, and exited with a bang at about 2 threads remaining. The flame that shot out between my legs made me thankful I do not wear polyester pants. Leather is best.

Mrunderhill1975a wrote: ↑Mon Dec 09, 2019 7:51 pm I used a triangular file to cut the notches, held the plug in a vise. The previous owner had blanked the decompressor hole with a plug. Western Cycle Supply was not yet in business at the time. The decompressor in question was one I picked up from Johnny's Speed and Chrome a few years back. It was a decompressor that I believe was for a vintage Triumph or BSA. I did not realize it, but, the thread length was considerably shorter on this decompressor than was a stock RE decompressor. Apparently, it was only long enough to engage 3 or 4 threads. Vibration caused the decompressor to back off, and exited with a bang at about 2 threads remaining. The flame that shot out between my legs made me thankful I do not wear polyester pants. Leather is best.

Oh man, you have the best stories! It surprises me the previous owner threw the decompressor in the trash. If you ever decide to go back to original equipment I know a guy.