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- LOCATION
- Lake County, Central Florida
Static water line...................
You mentioned that your waterline in your barrel was barely over the cavitation plate. That is a very low static waterline.
When you actually put the engine on the transom and in the water with the normal load onboard that you typically carry you will notice that the waterline on the engine will be drastically different that what it was in the barrel.
That is a change in your static water line. What does this mean or why is it important?
A 2-stroke outboard with small displacement is always a compromise between good WOT performance vs overall running quality through the range.
Very often smaller engines are ported to get the most usable horsepower out of them at a bit of expense of a good idle.....there is one of the compromises mentioned earlier. Not going into cross-flow vs. loop charged but there is a difference in the way they run and idle as well.
So....what does this static water line have to do with idle quality?
The higher the static water line the more back pressure you place on the exhaust. The more back pressure the harder it is to get the exhaust out before we get exhaust reversion at idle through the exhaust port.
What does exhaust reversion have to do with anything?
It dilutes the incoming fresh fuel/air charge for one. Secondly and possibly more important is that it kills some of the crankcase signal (pressure and vacuum inside the crankcase) which can affect your idle mixture and quality.
Static water line and propeller differences (load change) are the two biggest reasons why manufacturers stated a "recommended" Idle needle setting on a carburetor. It is just an initial setting and your engine and it's variables will probably necessitate a deviation of that initial recommendation.
Since you have a tendency to do your homework you will find there are tons of folks who believe the engine should run near perfect at the initial recommended needle setting. Before you go into deeper troubleshooting make some changes in your needle settings to see if you can get a better cold start.
You have yet to mention if you have verified spark or I missed it somewhere?
You mentioned that your waterline in your barrel was barely over the cavitation plate. That is a very low static waterline.
When you actually put the engine on the transom and in the water with the normal load onboard that you typically carry you will notice that the waterline on the engine will be drastically different that what it was in the barrel.
That is a change in your static water line. What does this mean or why is it important?
A 2-stroke outboard with small displacement is always a compromise between good WOT performance vs overall running quality through the range.
Very often smaller engines are ported to get the most usable horsepower out of them at a bit of expense of a good idle.....there is one of the compromises mentioned earlier. Not going into cross-flow vs. loop charged but there is a difference in the way they run and idle as well.
So....what does this static water line have to do with idle quality?
The higher the static water line the more back pressure you place on the exhaust. The more back pressure the harder it is to get the exhaust out before we get exhaust reversion at idle through the exhaust port.
What does exhaust reversion have to do with anything?
It dilutes the incoming fresh fuel/air charge for one. Secondly and possibly more important is that it kills some of the crankcase signal (pressure and vacuum inside the crankcase) which can affect your idle mixture and quality.
Static water line and propeller differences (load change) are the two biggest reasons why manufacturers stated a "recommended" Idle needle setting on a carburetor. It is just an initial setting and your engine and it's variables will probably necessitate a deviation of that initial recommendation.
Since you have a tendency to do your homework you will find there are tons of folks who believe the engine should run near perfect at the initial recommended needle setting. Before you go into deeper troubleshooting make some changes in your needle settings to see if you can get a better cold start.
You have yet to mention if you have verified spark or I missed it somewhere?
