yamaha f-115 overspeed protection

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pine island fred

Lieutenant Junior Grade
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Dec 20, 2002
Messages
1,144
Looks like this is a good time to post as there is another question just below. Am finally able to pay attention to my boat again, 05 f-115 with 58 hrs. Original prop was a 13 dia. with a 19 pitch was able to make 4200 rpm and also make a lot of oil. Just got a new prop from I boats, 13 with a 15in. pitch. Took it out yesterday and found quite a change. Expected an 800 rpm increase but got more. Problem is when i hit 5600 ( fastest it has ever turned) the engine cut back to 4400 and stays there until I retard the throttle and can then bring it up again.
Question, is there an o-speed protection that will drop the rpm back or does it just limit the rpm to some max figure? Gas is not real fresh but by no means stale. Starts in 1/2 a revolution with no pinging, coughing, hesitation thru any power settings up to the 5600 mark. Any ideas?
By the way RODBOLT, will be in collington harbor for a week starting next tues. Would like to meet the YAMAHA guru in person! How can I find you? regards FRED
 
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rodbolt

Supreme Mariner
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Sep 1, 2003
Messages
20,066
Re: yamaha f-115 overspeed protection

call Joe's marine and ask for Tom.
the F115 rev limiter is supposed to activate about 6200 RPM. are you sure there is no fuel issues such as a restriction or partly clogged VST filter?
the F115 operating range is 5000-6000 RPM and we try to prop them for 6000.
 
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seapro_stevo

Seaman Apprentice
Joined
Aug 21, 2007
Messages
31
Re: yamaha f-115 overspeed protection

when you say that its making oil, do you mean because it is overpropped and lugging that it burns alot of oil?
 
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pine island fred

Lieutenant Junior Grade
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1,144
Re: yamaha f-115 overspeed protection

By making oil I ment that the crankcase was filling up. First time the oil was to the top of the dipstick. Changed oil/filter and shorted it by 1 qt. After 10 hrs. I gained 1 QT. RODBOLT suggested I was overproped, lesser pitch seemed to work. At the same time I made a mental note to always close the fuel shut off valve. When I put the boat together I elected not to use an anti-siphon valve on the tank. When I top off the tank there is always noticable pressure in the tank just like todays cars/trucks. Figure this is for somekind of enviromental reason, anyway the tank is pressurised till I start drawing from it. Could the pressurised fuel been leaking into the crankcase? What do I know! One or the other fixed it as the oil level now stays where I put it. regards FRED
 
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rodbolt

Supreme Mariner
Joined
Sep 1, 2003
Messages
20,066
Re: yamaha f-115 overspeed protection

sounds like your tank is not properly vented, that in itself can lead to high speed running issues as fuel cant be supplied from a non vented tank.
 
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pine island fred

Lieutenant Junior Grade
Joined
Dec 20, 2002
Messages
1,144
Re: yamaha f-115 overspeed protection

Got a new family car to replace a 96-T bird. Tank is always pressurized when I go to fill it. Blew the filler hose on my 97 ford truck by topping off the tank to much, once the hose blew the tank would not be pressurized. New hose $300 the tank holds pressure again. New aluminun built in tank in the console has no fitting for a vent line. Of course it has to be vented, I figure there is a vent valve in the cap that opens when a suction is created in the tank.
Will be in COLLINGTON in a few weeks, maby I can buy you a beer and dinner at the BLUE CRAB. Need to pick your mind on why my friends 200 hp. yamahas, 3 different motors, overheat and cant be corrected. All second hand motors and am doubtful they have ever been fresh water flushed. Think thats the problem but they dont want to hear it. Gives me incentive to flush my F115 after each use. You still at TOMS? regards fred
 
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rodbolt

Supreme Mariner
Joined
Sep 1, 2003
Messages
20,066
Re: yamaha f-115 overspeed protection

still at Joes, still hang out to much at the Crab ,still overpaid but the work is easy:).
 
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