On Fri, 21 Mar 2008 07:25:49 GMT, Jere Lull wrote:

On 2008-03-20 23:55:17 -0400, Bruce in Bangkok said:

First, yes, fiddling with the governor can cause the engine to
explode.

The seals were put on the governor for a reason.

It is doubtful that the factory adjusted the governor incorrectly..

I suggest that you first adjust the idle speed to about 900-1000 RPM
in neutral and check that the high speed RPM is 3600 RPM in neutral.

Once you get these settings made does the engine seem to run normally?

If so, try the same settings with the transmission in forward. Your
idle speed should be essentially the same but high RPM may be a few
hundred RPM lower. If you can't reach full RPM and you have black
smoke coming out the exhaust then your prop is too big. If you can't
reach full RPM and no black smoke then you may have clogged filters -
change them all and try again.

If this doesn't cure your problem then frankly (and not to make fun of
you) from your questions I would suggest that you would be advised to
get a proper mechanic to have a look at things.

Bruce-in-Bangkok
(correct email address for reply)

I usually agree with you, and mostly agree with what I see as your
intentions, but you got some things wrong in my hardly ever humble
opinion....

The factory could well have screwed things up. Their employees have
little if no investment, though my observation has been that they
usually do at least a decent job.

Most of the Japanese factories are so automated or use so many jigs
and fixtures that human error is reduced to a minimum. Not to say it
never happens but I think it is rare.

Minimum idle speed on our 2GM20F is set to a bit under 600. We were
warned to long-term idle/charge at about 1200, so that amounts to our
usual idle.

I know that.. Re read what I wrote. I wanted him to set the idle high
enough that low idle speed wouldn't be a factor. If the thing ran well
with the higher idle it would be easy to reset that later. I probably
should have elaborated on that in the original post.

With a properly pitched prop, there is no way we can pull full RPMs at
the dock in forward or reverse. We blow incredible black billows of
smoke trying.

Again, I should have been more detailed. If he gets black smoke at
full throttle while under way the prop is too big.

I kow that some people deliberately over prop with the idea that they
get better fuel economy because they are running at a lower RPM but I
didn't want to get into all that.

When we open the throttle to full while freely moving, we push past
hull speed, show the max RPMs we pitched for and blow a bit of black
smoke. That IMHO is about the way is should be.

Probably in real life that is about the best you can do. theoretically
you should have no black smoke. Big stationary engines are tuned that
way, but with a boat there are just too many variables. going up hill
or down; how dirty is the bottom; full tanks or empty; wind behind or
before.

I made a later post after finally finding a service manual.

I had a 2GM20 at one time and even after running it for a couple of
years I had no idea that it was as sophisticated as it is(for a little
engine, that is).


Bruce-in-Bangkok
(correct email address for reply)