Zodiac Medline 2 underpowered with Suzuki Df 140?
I have a new (Dec 05 approx 40 hours) Zodiac Medline 2 (6 Metre) with a Suzuki DF 140, 4 stroke engine.
My problem is that she will only rev to 5,000 RPM at a max speed of 30knots.
We have checked the throttle cables - both at the hand control and at the engine and they appear to be o.k. no restrictions, fully extended!
We have disconnected the throttle cables and operated the throttle lever on the engine with the RIB in the water - using a screw driver - yet we can still only get the above figures - which eliminate the cables!
We have disconnected the throttle cables and revved the engine in neutral and we can get the engine to rev to the recommended 6,200 RPM - so now we know that the engine is capable of revving to that figure but it will not rev to more than 5,000 RPM in motion.
I am running a 21 º x 14 Alloy prop and have tried a 19º prop which gave me an increase of about 200 RPM but no real speed increase.
Speed is measured with a Garmin 198 C Chart plotter.
Does anyone have any suggestions?