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Outboard in well
I recently purchased second hand a Honda 10hp. four stroke outboard for my RL24. While this outboard is on the very upper end of weight and power for an RL24 it provides a comfortable cruising option for longer trips in Moreton Bay and Fraser Island.

I have had the engine fully serviced and it was returned with positive reports. I am experiencing erratic revving on full throttle. On full throttle the engine will run at half revs the then jump up to full revs then return to half revs..and so on.

The outboard just fits in the outboard well with the head blocking most of the top of the well opening, which may be the cause of my problem. The outboard may be choking in its own exhaust fumes? I am advised that some outboard manufacturers offer an exhaust kit to vent away exhaust from the ait intake, Honda do not.

Has anyone experienced their outboard choking or stalling while at full throttle in the well?


Peter Lynch17-May-2006    Edit    Delete 
Re: Outboard in well
Hi, Peter
The only thing that i have experienced which has the same behaviour, Is cavatation, it can cause the engine to rev out (tends to happen with the larger size motors I have a 9.8Hp). When there's air around the prop there's no load so the engine will rev out. It normally only happens at full throttle because the water can't keep up to the high RPM of the prop. If you back the throttle off a bit it probably won't do it. If the prop isn't deep enough, it can also cause the cavatation.
Hope it helps
Cheers

Ben
Ben Skennerton17-May-2006    Edit    Delete 
Re: Outboard in well
I almost went demented with a similar problem Peter.

My old 8HP Honda 4 Stroke mounted in my RL24 continually acted erratically. It screamed in neutral then died. It died when changing from forward to reverse just as I was entering the berth. It would run perfectly then die just when I most needed it.

I took it to a large marine outfit at Toowoomba and asked them to duplicate the symtoms in the test tank. They reported there was nothing wrong. This happened three times; that is three times they reported it was OK and three times on Moreton Bay it let me down big time. They even suggested that it was my imagination. I told them to take a reality check as there was no way I was handing over cash each time because of imaginitis!

The 4th time I told them to run it in the test tank at a variety of RPM and not to contact me until they had discovered the problem.

Marvel! They discovered it. A faulty engine cut off switch which was shorting intermittently. The outboard has been as good as gold ever since they replaced the switch.

Of course it may be that your problem is entirely different. However, the lesson learned for me was, if I could not fix it, not to cave in to the so called experts.

Hope my experience is of assistance to you.

Best wishes
Terry
AWOL RL24

Terry17-May-2006    Edit    Delete 
Re: Outboard in well
Sounds a bit more like a fuel supply - over supply or under supply problem
Have you considered
* water in the fuel - tank , carby bowl, line - there's the old half a cup of meths trick...but i'd start with a serious filter cleanin carb in lne and in the tank
* sticking carby float - had the same symptoms at RL tiles immediately after engine was serviced - gunk in the needle & seat
* height of tank in relation to engine (unlikely) - too great ahead of pressure
* bad carby settings too rich.... more of a low speed & idle prob - consult engine manual
* using cheap oil that fouls plugs ...always go the top shelf stuff like quicksilver


Maqybe try & test your theory...If it was really choking on its own fumes it wouldn't be very likely to happen on really breezy days underway where the fumes are carried a way and clean air is force fed ... on a light breeze under way with the cowl off you'd expect minimal probs you'd expect minimal probs....it would be much much worse at idle calm air boat not moving

wayne hill23-May-2006    Edit    Delete 
Re: Outboard in well
Thanks for all the good advice and suggestions. I discovered after running the outbord on a tinny that it was a faulty spark plug in one of the cylinders that was causing the erratic drop in power (ie. engine running on one cylinder). Goes to show that despite a full service including a spark plug replacement that faliure can occur very early on in the life of a spark plug.
peter Lynch25-May-2006    Edit    Delete 
Re: Outboard in well
Cavitation also occurs occasionaly while turning the boat sharply. I have a Tohasu 6hp 4stoke with low boat speed pitch prop (fine). Try it inturns see if it gives you the same symptom. With more power the more likely you will cavitate. Try this also >use a GPS and gradualy increase engine power until the boat reaches displacement speed 5>6 kts with my boat (no wind). See how much more speed you get relative to increasing to full throtle. Displacement speed is a bit of solid wall pushing against it uses a lot of fuel for little speed increase. Save that extra power for headwinds and waves.
Drean on3-Jun-2006    Edit    Delete 

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