RPM RANGE FOR 75 HP YANMARS

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jbrad
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RPM RANGE FOR 75 HP YANMARS

Post by jbrad »

HI FOLKS,

I AM HAVING SOME WHAT OF A PROBLEM DETERMINING WHAT THE TOP RANGE RPM SHOULD BE FOR " MR BUSY " MV 059. I WOULD LIKE TO KNOW THE RANGE THAT OTHERS WITH THE SAME ENGINES WITH THE FACTORY THREE BLADE PROPS ARE GETTING. CURRENTLY MINE IS TOPPING OUT AT 3150-3175. I HAVE CHECKED RUNNING GEAR, BOTTOM CLEANLINESS, RUDDER ALIGNMENT AND HAD NEW FILTERS 30 HRS PREVIOUS. ENGINE ARE RUNNING FINE, NO SMOKE ETC. ANY IDEAS OULD BE APPRECIATED.
MR BUSY
duetto
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Post by duetto »

hi,

with full cruising gear, folding bikes, rib w/15hp yamaha, full fuel and water, mv 23 is topping out at 3400 rpm in 1' Long Island Sound chop.

john cummings

duetto mv23
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Mishigas
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Post by Mishigas »

What speed are you running at top RPM average. The 75 hp Yanmars are rated at 3800 RPM with no load, out of gear. A mechanic can tach your engines because the Yanmar tachs can be off a little as mine are. I am told that if a prop is even a little out of balance it can change your running RPM. In your slip, take them out of gear and bring one engine at a time to top speed for a few seconds each and record your RPMs. They should be even and reach about 3800 again with no load. At least you'll know if the engines are hitting the rated RPMs.
Sandy K "MISHIGAS" MV34
ELIXIR
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Post by ELIXIR »

I have hull 63 and bringing it south found there was a difference in the max rpm's between the engines under way. Yanmar mechanic says there is an adjustment that can be made to the engines to increase their rpms when too low. Akin to a throttle adjustment. He puts tach on them and them makes the adjustment. The Mishigas reply comment on proper tach readings is correct.
jbrad
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Post by jbrad »

THANKS FOR THE INFO AND RESPONSES. I WILL LET YOU KNOW HOW THE TALE UNFOLDS.

JIMMY B
MR BUSY
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