I've got a Yanmar 2gm20 that I'm pretty convinced has a problem with
the governor (speed is not well controlled especially when it comes
under load). The seemingly easy path is to fiddle with the injection
limiter. However, there are a couple of things holding me back.
First, they put a wire seal on the adjuster back at the factory. I've
had the problem from day one so I suspect that they didn't get the
adjustment right, but still I figure they sealed it for a reason. I'm
no Japanese scholar but it may even say "Tom, keep your **** hands off
this!" So, will really bad things happen if I mess with the limiter?
Second, I'm not sure exactly how to go about making the adjustment
should I care to. The manual says "if the engine does not accelerate
smoothly turn the limiter slightly counter-clockwise." Good, that's
my problem. The drawing shows a cap nut, lock nut and injection
control shaft. I presume I have to remove the nuts and back the
injection control shaft off a fraction. But, the drawing doesn't show
a slot or anything on the control shaft to keep it from turning while
I move the nuts. Is there some trick to making this work I should know
about when I attempt this? It'd be really nice if I could mark things
so I could at least get back to the current settings if fiddling
doesn't fix things. But how? Thanks!

-- Tom.