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Old 06 October 2006, 19:38   #11
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I attach a picture of the engine as she is mounted on the transom
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Old 06 October 2006, 20:05   #12
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Photo should have been taken with engine down. Just a guess, but based on photo the engine is mounted too high or wrong shaft length.
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Old 07 October 2006, 13:04   #13
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Hold tight - photos on the way!
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Old 07 October 2006, 14:56   #14
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Yup, it is on the high side. I would guess 2-3 inches. Cavitation plate should be level with bottom of transom. You can always trim out for more performance once you have got the engine postioned properly.
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Old 07 October 2006, 14:57   #15
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Whoever mounted that engine should be shot
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Old 07 October 2006, 15:21   #16
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The engine is mounted on the centre of five holes on the engine mounting plate/transom (see photograph).

There is approximately 1.5" of movement on the engine bracket if the engine was lowered - would this solve the problem?
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Old 07 October 2006, 16:22   #17
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Quote:
Originally Posted by Beitsta
My problem is that she will only rev to 5,000 RPM
If the engine was mounted too high, I'd expect it to over rev and cavitate.

There are three fins on the Suzuki and the antivent plate (bottom one of the three) looks more or less level to me. Level with the keel is only a rule of thumb anyway as lots of ribs (Ospreys included) run with the plate 1"-2" above the keel line.

To find the extra 1000rpm I'd try a 17" pitch prop, more out-trim when on the plane or better balancing of the boat before messing with the engine height.

Also those transom add-ons look like they are set too low.

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Old 07 October 2006, 17:17   #18
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The lower unit on that Soozook looks as if it's done a lot of work. Is the engine older than Dec 2005? If it's done a lot of hours, then it may be worth doing a conpression test, to see whether you're losing something there.
I wouldn't get concerned about fuel starvation - if there's enough getting through to run it at 5000 rpm, there should be enough for 6000+. Fuel starvation will cause the engine to virtually cut out, rather than lose a few rpm at the top end of the range.
As DM says, mounting the engine high will reduce drag, resulting in higher, rather than lower peak rpm, so dropping it is unlikely to help you.
A drop in prop pitch will probably be the best way forward, if the powerhead is making the full 140 ponies.
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Old 07 October 2006, 18:03   #19
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Davidmanning:

'Also those transom add-ons look like they are set too low.' What do you mean??
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Old 07 October 2006, 18:06   #20
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Downhilldai:

I reversed the unit on the trailer against a kerb in my own driveway and just caught the Skeg ... the engine was brand new Dec 2005 when I purchased the RIB
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