Jan wrote:

All as already suggested & ........

Hi everyone,

I got a Evinrude engine from a friend to check it out, he told me it
ran bad. I took off the carb and cleaned it out after that it ran
fine.
Now not long after that during (has been going good that day) a small
boat trip engine started to run rough especially when running at
higher rpm. It's harder to notice it when I try to run it idle.

Hmmm this sorta rules out the idle jet, it's the adjustable one, so
at high rpm the engine is running mostly on the non adjustable main jet.


Coming home I took off the float chamber and noticed a dusthair in the
main jet. Removed it and being convinced that would have caused it
put things back together, also installed a simple fuel filter to
prevent this from happening again. (does this engine has a filter in
the carb?).
But on a fishing trip yesterday after about 5 minutes the engine
started to do the same again.
I checked out the newsgroupes but the answers vary quite a bit.
Since my engine is so simple of construction I suspect a simple answer
for this problem. It's a 2 stroke, 2 cylinder, 4 HP Evinrude from '86
with one carburator.
By the way, I find only one adjusting screw on the carb, where is it
for and how many turns out should it be?

The wet interior you mentioned to Tony tends to indicate lack of
spark in that cyl?? It has 2 coils so when you put the head back on make
sure the coil connections & particularly their earthing is all tickety
boo.

If it persists, disconnect each lead in turn when running (should
then be grounded but .....) & determine if it is losing spark on one cyl
after a little running + heat. If so swap the bits & pieces from cyl to
cyl till the fault follows to the other cyl, to ID the offending
component.

K



Your help is much appreciated,

Jan.
(Honda CB 400N '79)
(Honda CB 750 Sevenfifty '92)
(Yamaha TDM 850 '98)