Intermittent "cough" during startup.

[The Force power]

Testing while tied to the dock is about the same as testing in your
yard.
You can do the tests on the trailer but problems need to be addressed in the water and in gear moving.
The rpm's on the trailer or in N 11-1200 in gear 750-800

how so? tied to the dock would simulate a "test-tank" correct??

 

[jerryjerry05]

No "tank test" refers to a test using a test wheel.
Not many have the test wheel and the 1000gal tank.

 

[The Force power]

No "tank test" refers to a test using a test wheel.
Not many have the test wheel and the 1000gal tank.

Good point!
I don't have a test wheel either, but I do have test-tank and with a 15 P prop attached I can run it in gear at idle-speed to verify/adjust the RPMs

 

[Redbarron%%]

Testing tied to the dock can easily simulate idling tied to the dock. In my case tied to the dock it can simulate from idle to WOT as I have a Sport jet and the RPM seems the same underway or TTTD.
Actually they suggest idle be final adjusted with the boat being allowed to move and someone else manning the helm.

 

[The Force power]

Actually they suggest idle be final adjusted with the boat being allowed to move and someone else manning the helm.

And that...... (I'm sure) was what jerryjerry05 was referring to

 

[DunbarLtd]

Turning the air screws counter clockwise (rich) did nothing to the way it ran as far as I could tell. It just smoked like crazy. I went as far as 3 turns out.

However, turning the air screws clockwise (lean) increased the rpm quite a bit. But it never popped or anything. The rpms just went through the roof so i quickly turned it back to where i started.

When I had the air screws very rich the motor still coughed upon restart. I went by the book and adjusted, ran WOT to clear it out, then let sit 1 minute and then holeshot and so on.

For now I put them back to 1 turn out and may leave them there. I just cant tune this thing I guess.

I did however adjust the idle speed a little and got it to idle in gear about 675-700rpms. Seems to do fine and doesnt want to die when shifting into gear but still "loads up" like crazy if it idles in gear for too long. Its evident during a hole shot. When I open it up and give it WOT for a couple minutes, then do a holeshot right away...its fine.

Thanks for the advice anyways. Its an old motor. It starts. It runs. Id love to fine tune the thing but I just have no clue what to listen for I guess.

 

[Sea Rider]

I googled it.....Lower Explosive Limit.....and Upper Explosive Limit......one would think gas would burn at all times, but not so. Interesting info. My engine "coughs" sometimes too, but only on the first start...after that, no problem.

Coughs same on next day outing, say first start of the day ? Probably the motor isn't being fully warmed up in such scenario, runs too cold ? Are the t-stats in top working order ? If wanting to set all 3 carb's pilot jets to work spot on, need to buy an electronic vacuum tester...

Happy Boating​

 

[topgun3690]

Coughs same on next day outing, say first start of the day ? Probably the motor isn't being fully warmed up in such scenario, runs too cold ? Are the t-stats in top working order ? If wanting to set all 3 carb's pilot jets to work spot on, need to buy an electronic vacuum tester...

Happy Boating​

It only "coughs" on the first start after sitting for a week or two....after that is fine. So, on next day outing no cough, only after it sits up for a while. Thanks Sea Rider for your input.

 

[DunbarLtd]

Yea I remember last summer I went out one morning to fart around and then went home shortly after. I then talked to a buddy who wanted to go out maybe 4 hours later. When I launched the boat the engine fired right up first crank. 2 strokes are weird.

And yes my t-stat is good. I changed it i think last season.

When I headed for the docks at the end of the day on my last trip out I stopped for maybe 20 minutes and the engine fired up without coughing. To me, it is completely random when it happens which makes it very difficult to diagnose. But after sitting for a while it definitely coughs a couple times on first start.

 

[jerryjerry05]

The cough: could be the primer is feeding too much
fuel, the air screw not set quite right, water in the fuel(small
amount) the starting procedure and probably a million other reasons??

MERRY CHRISTMAS!!

 

[Redbarron%%]

Hell if it starts with no ether starting fluid and just a cough then be happy and smile

 

[DunbarLtd]

Exactly Redbarron. Im just happy it starts and runs without many issues.

One other idea I had is the starter? Is it possible it is not spinning the flywheel fast enough? Or since I have instant starts sometimes Im assuming its fine.

And a big thank you to everyone for their advice. Merry Christmas!

 

[jerryjerry05]

Slow turning, would cause hard starting not a cough.

 

[DunbarLtd]

Thanks Jerry, Merry Christmas!

 

[racerone]

When piston is at the bottom of the stroke the crankcase ( with fresh fuel ) is the OPEN to the exhaust and any fire in the exhaust manifold.