This may interest Norton owners as I have seen the use of decompressor buttons on high comp Norton engines.

[SteveA]

I recall Comstock looking at installing a decompression release and concluded there wasn't enough room.

'compression release' yes....decompression release?

Not sure about that one.

 

[NORTSTER1974]

Is there room for a socket on the spark plug, or am I just seeing it from the wrong angle?

I would think that's why TC "Hog Slayer" went in from the side. He told me it was a tricky set up. Set up was most of the work. Harley's usually went in through the top. As you can see the OP said he had done some on Harley's so he took that approach. Same dog, different leash.

 

[seattle##gs]

I've installed several on Harleys. I'll be experimenting with this on a spare 750 head this week.

I used the same location but the angle is different. The hole into the combustion chamber comes in at the edge of the combustion chamber. Fitting the sparkplug socket is very close.

 

[Tornado]

On Velos an exhaust valve lifter is used to help get over tdc. It works via a cable operated lever sitting on the cam follower through the timing casing.

 

[robs ss]

On Velos an exhaust valve lifter is used to help get over tdc. It works via a cable operated lever sitting on the cam follower through the timing casing.

Same on Norton ES2 and Model 50, except it's a lever through the left side of the rocker cover