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Author Topic:   Break-in Yamaha 90-HP 2s on NEWPORT
flawton posted 03-23-2003 08:52 AM ET (US)   Profile for flawton   Send Email to flawton  
The 1981 NEWPORT hit the water for the first time in at least 7 years yesterday. Started the break-in on the 2003 90-HP Yamaha 2s and put a total of 3.5 hrs on it. Per the owner's manual and the dealer's recommendation, during the 3rd hour of break-in I took a peek at WOT (20-30 secs). On three different brief WOT passes with varying wind directions and surface condition my tach registered 5,200 RPM and I am running a 13x17 SS OEM Yamaha prop (5,500 RPM is the goal from what i have been told). I had 400 lbs of people, 6 gallons of fuel (using portable tank for break-in, not under RPS tank), a battery (under console), and maybe 75 lbs of miscellaneous gear so my load was average, not light. My dealer will allow me to swap out the prop if it is not the correct one (and it is not nicked). I noticed the engine loosened up around the 2.5 hour mark. Should I switch to a different prop to get up to the recommended 5,500 RPM? Will the engine "loosen up" following break-in and get to the proper operating range? The load I had today is probably going to be on the lighter end of what I will carry considering that following break-in I will use the 26 gallon tank under the RPS, and my friends and I don't seem to be getting lighter with age. ;O

My reason for all the rambling: I managed to go the first 3.5 hours without a nick on the prop. I dont want to push my luck and get stuck with the wrong prop.

Any help would be greatly appreciated.

BTW, the NEWPORT really looked great around all of the glitter bass boats on Lake Oconee.

Clark Roberts posted 03-23-2003 10:20 AM ET (US)     Profile for Clark Roberts  Send Email to Clark Roberts     
Flawton, suggest a few more hrs... maybe 10, then raise engine so that anti-cavitation plate is approx an inch above keel (bottom of hull) and see what happens! you may be able to swing that 17" prop up to 5500-5600. I have had several Montauks with 90 Yamahas and non would spin a 17 (all did ok with a 15" pitch stainless OEM or Power Tech brand. Didn't have much luck with Stilletto's for some strange reason... happy Whalin'... Clark..SCN
Bigshot posted 03-23-2003 10:34 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Had the EXACT same setup on my Montauk. With 2 people and a full 27 Pate she would spin 5400. It was about an inch to 1.5" above keel. With one person she hit 5500 with four like 51-5200. It was PERFECT.
jimh posted 03-23-2003 10:59 AM ET (US)     Profile for jimh  Send Email to jimh     
[Administrative post]
flawton posted 03-23-2003 12:41 PM ET (US)     Profile for flawton  Send Email to flawton     
Thw anticavitation plate is approximately 1/2" above the keel. I dont plan on much WOT opperation, Im more interested in cruising and engine longitivity. thanks for the replies
flawton posted 03-23-2003 03:20 PM ET (US)     Profile for flawton  Send Email to flawton     
As an afterthought, would the difference in density in freshwater vs. saltwater affect performance? yesterday's run was in freshwater and most of my time will be spent in saltwater.
flawton posted 03-23-2003 08:09 PM ET (US)     Profile for flawton  Send Email to flawton     
So that extra 1" up ,from 0.5" to 1.5", above the keel makes that big of a difference? I had my partner drive while I looked over the transom at about 3500 rpms and the top of the two plates was above the water and spraying water outward. Is there a concern at 1.5" above the transom that the cooling water supply wouldn't be adequate?

Just trying to get the best out of the $$$s & personal time I just laid down.

thanks again

John from Madison CT posted 03-24-2003 07:24 AM ET (US)     Profile for John from Madison CT  Send Email to John from Madison CT     
The 17" pitch Prop IS the one for a Montauk/Newport and a Yamaha 90hp.

Give her some time to break in. I wouldn't really judge her until at least 10 hours.

Like suggested, after all is broken in, you can try raising the motor one hole, but going to a 15" pitch prop does not seem prudent to me.


Clark Roberts posted 03-24-2003 07:37 AM ET (US)     Profile for Clark Roberts  Send Email to Clark Roberts     
Flawton, the extra one inch "up" could make a big difference (could!) and yes adequate cooling water intake/flow is always a concern when raising engine. A fin (like Doel-Fin) will tend to keep water on prop and into cooling intake but trim angle also has an effect on air intrusion into cooling sys... The use of a cyl head/jacket water temp gauge and water press gauge are the only way to tell for sure as the "tattle tale" stream can look fine while upper cyls are not getting proper water flow/press. My reasons for raising engines is to get less total draft and run in very shallow water otherwise I would not raise my engines so high (most are on jackplates and I'm constantly fiddling with everything... some of us can never let well enough alone!!!). I doubt if you will notice a difference in rpm in salt vs. fresh water operation but you will notice an rpm drop on hot summer days in 90's vs. cooler days in 50's/60's ... etc.. etc... Happy Whalin'.. Clark
flawton posted 03-24-2003 12:34 PM ET (US)     Profile for flawton  Send Email to flawton     
As always thanks for the info. Im gonna stick with the 17". Im heading out to a local lake tommorrow sollo and see what happens with a light load.
PMUCCIOLO posted 03-24-2003 01:28 PM ET (US)     Profile for PMUCCIOLO    

My 17'Alert when loaded similar to what you've described, performed the same during its break-in period.

I'd stick with the 17" propeller and allow the engine some time for the rings to "seat."


John from Madison CT posted 03-25-2003 07:10 AM ET (US)     Profile for John from Madison CT  Send Email to John from Madison CT     

FWIW, if you are at 5300, or 5400 RPM's do not sweat it. Those 3 cyl, Yamaha 90's are extremely rugged. They are used extensively for commerial use and you hear stories of 4000 hours put on them.

Commercially, they beat the daylights out of engines, and that's why many use these Yammie 90's.

Anything over 5200RPM's and I'd leave her alone.

Good Luck,

John from Madison, CT

flawton posted 03-25-2003 04:08 PM ET (US)     Profile for flawton  Send Email to flawton     
Solo today I hit 5400 rpm at WOT. Looks like everything is ok. Im loving this boat.

Thanks for the input all.

Bigshot posted 03-25-2003 04:26 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Leave it alone!

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