92 SP rough running extended idle

[tregger]

I have a 92 SP with the white 587. The machine starts easily in and out of water. It runs fine at idle/warmup, smooth transition from idle to power, runs great from idle to WOT.

I run it on a river that has several extended no-wake zones. About halfway through the no-wake zone idle will become rough, as if the machine wants to die and starts vibrating. This issue is not related to debris in pump. Everything seems to be set ok since power delivery is good in most cases. Oil pump arm is lined up with the line on the pump for factory setting. Once free of the no-wake power delivery is smooth up to WOT. I replace plugs a few times a year, they never look significantly fouled/dirty. Carb/fuel pump rebuilt 2 years ago.

I will note that this machine makes significantly less smoke than my 1990 SP 587, which may just be a difference between yellow/white engines.

Any ideas would be helpful! Thanks!

 

[burtshaver2021]

Sounds like your loading up on fuel, try turning your low speed screw in 1/8th of a turn or maybe even a little less 1/16th if you can. If you can in the no wake wake zone, can you blip the throttle every now and then?

 

[tregger]

applying throttle makes the machine run better, but only while throttle is opened. If the machine goes back to idle it runs poorly. Maybe this supports your suggestion of too much fuel/rich. I can try backing down the low speed a tiny bit, Thank you!

 

[tomski]

I personally set my idle a little higher than normal, helping it to not load up...and if you think you're kicking up to much wake, I would simply let those concerned folks know that "it's a very old machine and it's as slow as it can go!"...then follow up with, " I'M JUST GLAD IT'S RUNNING!!"