The timing inspection hole plug (centered between the two cylinders on the right crankcase) can be troublesome to remove and even harder to install.

Once removed, check the threads on the plug and in the case for damage before trying to re-install the plug. These are straight (not tapered) threads. Inspect them closely and in the case of warped or damaged threads, first try to repair or 'chase' the threads, see also warped or damaged thread repair.This will keep you from having to drill into the case. You can use a tap for the case and / or a die for the plug.

If chasing the threads doesn't work or leave enough meat to allow the plug to tighten without stripping, you may have to do some work on the hole and buy an oversized acorn style plug and tap kit for rethreading the stripped out timing hole. The taps that comes with this kit either has a taper or a pilot on the end ²⁾ that will need to be cut off with a grinder or a Dremil cutting tool before use.

When chasing these threads with a tap, you'll need a 5/8”x18 'bottoming' tap which is flat on the end.

There is not enough room between the outside of the case and the crankshaft to use a tapered end tap. This could possibly end with you running in too far with the tap before you get good threads, pushing against the crankshaft (which will create back pressure as you continue turning) and crack the case.

It's a good idea to stuff one solid section of panty hose into the hole prior to any work. So the hole is stuffed but material is not in the way to work (mostly down between the case and the crankshaft with a little sticking up). Use some thick grease on the tap to minimize snagging the panty hose and to catch the cut shavings in the flutes of the tap. When the job is complete grab the panty hose with a hook pick and needle nose pliers and pull it out. Any foreign material with be stuck to the panty hose. ⁷⁾

Carefully run the tap in with your hand to get centered and catch the first threads.

This is best done with the gearcase cover off. Options at this point include a small crescent wrench on the tap while holding it centered with the other hand, an 8 or 12 point socket that fits the end of the tap, or a tap socket. ^{9) 10) 11)}

Since the plug doesn't run in the full length of case thread, you don't have to chase all the way until the tap touches the crank.

The case threads are a little more than 1/4“ longer than the plug threads. This will also help you control how deep of shavings you would have to clean out before installing the plug.