wrote in message
...
On Sun, 3 May 2009 14:04:53 -0600, "SteveB"
wrote:

Took my Lund/Merc 40 4 cyl 2 cycle fishing the last two days. It cuts out
quite a bit, and I'm suspecting jetting. The gas is fresh. Plugs are
new.

I need to buy a manual, but don't want to part with the $$$. I've done a
lot of carb adjustments on cars, motorcycles, atv's, etc.

This motor has two carbs. Are the low speed jets just brass screws that
you
adjust at a high idle? Something was mentioned about high speed jets, and
do those need to be adjusted when the boat is going fast? Or is it a
thing
of 1 1/2 turn from closed, or something like that?


The idle jets are adjusted similar to your old cars.
Run then in tight and back them out 1 1/4 - 1 12 turns for a starting
point. That only affects the idle. The high speed jets are fixed.

I doubt this will fix anything.

What do you mean "cutting out?"

If this is a gradual cutting in and out I would still be looking at
fuel but if it is abrupt you could have an ignition problem. Can you
figure out if this is just one cylinder?

The "cutting out" is mainly I feel that it does not attain highest rpms
possible. It does not spit or sputter at high speed, but does it quite a
bit at low between idle and about 5 mph.

I did not really dig into the engine yet. I completely rebuilt an Evinrude
60 that sucked a stainless washer into a cylinder, so think I could just
disassemble and check float bowls, etc, and fiddle with the low speed jets
in a tank of water. I kinda figured the 1.5 turn thing, as that seems to be
standard, tho not for all. My ATV is 1 1/8 turn. go figger. I will
eventually take this to a real mechanic at a shop, but I just hate paying
big bucks for small simple fixes that I can do.

Until then, there's a list of things I need to work on in the boat, as is
common with all boats. For now, it runs okay, just that low speed stalling
problem that's aggravating.

Thanks for the help.

Steve