Going slowly with an outboard - is it a good idea?

[SnaxMuppet]

I have a 115hp outboard and apart from the times when I want to go out for a bit of a blast I expect that I will be running off the plane and at low rpm and it occurred to me that it might not be a good idea to run the engine for long periods at low rpm?

Clearly, most outboard are designed for running in the upper part of their normal operating range so would I be harming my engine if I ran it for the majority of the time at low rpm (say under 2000rpm when normal range is to 6000rpm)?

Is there anything I could do or should do extra if I am running the engine like that?

 

[RobWales]

Modern 4 strokes are fine at this sorta thing,its the older 2 strokes that would cause problems with oiling the plugs etc.

Nice new boat,enjoy it.

Rob

 

[andyball]

Hi

had the same engine - same usage over 300hrs - No probs at all.

 

[AHoy2]

Just make sure to run it in fully (using the full rev range) first before spending extended time at low revs.

 

[Lakesailor]

Only if they're not set up and maintained properly. I've a similar issue with a Johnson 70VRO and been having a bit of intermitant missfiring. The motor's new to me so I have been going through all the basic tests and seem to have found the problem.
In scouring the iboats.com forums I came across an outboard "guru" who for a bet travelled 24 miles at tickover with a 120 hp 2 stroke without it missing a beat.
A new 4 stroke, properly maintained, should be as regular as clockwork, whatever speeds it runs at.

 

[Major Catastrophe]

No problem Arny, just make sure you follow the break in to the letter. I potter for a couple of hours at 5 knots in my fruitless hunt for fish and the engine never misses a beat if I suddenly decide to gun it.

When I get back to my berth I always leave the engine to idle for few minutes and then switch off, lift it up and then attach a flushing hose to the upper flushing port. I leave that to run for 30 to 60 minutes while I tidy the boat, I then unclip the hose and then wash the boat before locking up.

 

[mjf]

Yes i agree.

i have a new 4 stroke Yammy and used it for 8 hours the other w/e at tick over most of the time with an occassional 'blat' at higher revs and the odd FOT.

 

[vanoord]

Should be fine, albeit that on a hot day I've had an outboard overheat after about half an hour at tickover (in gear). Basically, the slow speed meant the water pump was running slower and not getting up to pressure - as it was an Optimax with SmartCraft instruments, I watched the temperature slowly rising until the buzzer went off... a quick blast of throttle and it cooled down pronto.

 

[Jonmendez]

You will have no problems running a new 4 stroke O/B at low revs. Our 200 HP runs at low revs for 6 hours at a time on a Level 2 course with no problems. As others have said, it was always a problem with 2 strokes as the plugs would oil up and the engine would play up.

 

[SnaxMuppet]

Many thanks to everyone.

I feel happy now running at low revs but I am still in the running-in phase and so for now I am using the allowable revs to get it properly run in and will resume normal ops after that.

Many thanks again.