115 4 stroke low end speed

[pogieeh]

Before I brought this to the dealer, I had this problem with my yamaha 115 4 stroke. Has a 13 5/8 x 13 pitch. Only has 90 hrs. Problem is that it won't go over 10 NMPH. Sometimes it does after 20-30 minutes of WOT and you can tell the sound that the last cylinder kicks in and it tops at 25-28 NMPH. It sits on a 1851 CC seaswirl center console. After it tops and I decrease the throttle, and increase it back up, it stays at 10 NMPH again for a long time. It's in an authorize YAMAHA service and they couldn't find anything wrong with it. They did a dyno and it's all within YAMAHA's specs. Can anyone please help me with this scenario? Thanks.

 

[imported_Curmudgeon]

Re: 115 4 stroke low end speed

Did they water test it? What's the RPM? Is it still in waranty? Is your anchor stowed?

 

[pogieeh]

Re: 115 4 stroke low end speed

Originally posted by Old Curmudgeon:<br /> Did they water test it? What's the RPM? Is it still in waranty? Is your anchor stowed?

They did the water test and no water found. It's still in the shop and still no luck finding the problem. Waranty is out. It's an outboard. Forgot to mention. At 10 NMP the rpm is at 5300. When it picks up the speed sometimes, it goes up to 5800 rpm. Thanks.

 

[bossee]

Re: 115 4 stroke low end speed

Hi,<br /><br />I use a Yamaha F115, 2003.<br />I use 13 x 19 Yamaha Black steel prop.<br />With that prop I get about 5700 RPM on my boat at full trottle.<br /><br /> http://www.yamaha-motor.com/outboar...tail/5/256/1093/8455/all/1/3956/0/detail.aspx <br /><br />I find Your prop 13 5/8 (diam) x 13 (pitch) little odd. Maybe You should borrow a 13 x 19 or 13 x 17 Yamaha Black steel prop and see how it will behave?<br /><br /><br />Do You have a spun prop? (the center rubber in the prop came loose?)<br /><br />Max RPM at full throttle can be 6000 on a F115 accordong to Owner's Manual without any harm to it.<br /><br />Check the buttom of the boat -is it clean and smooth (no barnacle?)<br /><br />Is the anticavitation plate level with the keel line when outboard is vertical?<br /><br />The boat has a transom for a long shaft outboard and You have a long shaft F115 - Right?<br /><br />I checked out how the boat looked like and it seems a nice boat:<br /><br /> http://www.seaswirl.com/Boats/Boats_Detail.asp?bid=318 <br />------------------------------------<br />LOA<br />18'6" • 5.64 M <br />Beam <br />90" • 2.29 M <br />Deadrise <br />20° <br />Weight with Std. Engine (Approx.) <br />2,450 LBS. • 1,111 KG <br />Draft Drive Down <br />30" • 0.76 M <br />Weight Capacity <br />1,900 LBS. • 862 KG <br /> Maximum Horsepower <br />175 HP • 130 KW <br />Standard Horsepower <br />115 HP • 86 KW <br />Fuel Capacity <br />62 GAL. • 235 L <br />Bridge Clearance <br />70" • 1.78 M <br />Bait Tank Size <br />30 GAL. • 114 L <br />-------------------------------<br /><br />A Yamaha F115 should handle that boat without to much effort.

 

[pogieeh]

Re: 115 4 stroke low end speed

That is the first thing they checked is the prop. The recommended it 13 x 15, but the 13 pitch won't matter in this case since it responds sometimes and will rev to 5800 rpm. It's just kind of odd that it's not consistent to pick up it's speed. I have the long shaft F115. Thanks.

 

[stinkylinky]

Re: 115 4 stroke low end speed

I find a 13 pitch prop to be very shallow pitch (gut feeling).<br /><br />I have a 2001 Javelin (Stratos) Fish & Ski. It weighs 1300 pounds dry (boat) and about 2000 pounds with gear and 2002 Yamaha F115. Thiese are slightly lighter numbers than listed above.<br /><br />My prop is 13.25 x 17 Stainless Steel. I wish it had a little more low end for skiing, but it tops out at 47 mph (GPS).<br /><br />The dealer originally put a 13.25 x 21 SS on it. I could not get out of the hole, nor produce over 4500 RPM WOT. Previous owner ran 12.5 x 21 Aluminum.<br /><br />As previously suggested, see if you can try a taller pitch prop in the same diameter. Maybe 17 if Stainless or 19 if Aluminum.

 

[pogieeh]

Re: 115 4 stroke low end speed

Yamaha recommended a 13x15 to get top end speed. I had before changing it to 13 pitch. Top end is 30 NMPH. I tried a 21 pitch alum. and it slowed down to 12 NMPH and 4200 RPM. Any other recommendations is greatly appreciated. Thanks.

 

[stinkylinky]

Re: 115 4 stroke low end speed

This performance bulletin should give you some comparative information.<br /><br /> http://www.yamaha-motor.com/assets/...rokePerf_MidThrustJetPort_115hp_037-GLS-A.pdf <br /><br />They indicate 13.5 x 19 prop and report similar performance to what I experience. (Note: my prop is 13.5 inch diameter, not 13.25 as I indicated above).

 

[pogieeh]

Re: 115 4 stroke low end speed

I just got a call from the shop and they found the problem. It's the harness wire that is connected to the fuel injectors that lost the plastic coating. So the wire was bare and when it bounces in the ocean it takes it out of it's place and doesn't create a spark to trigger the last cylinder. Make sense, something like that. Any feedback is greatly appreciated. Thanks.