RPM/WOT Evinrude 115 1977

[KYHunter2]

Re: RPM/WOT Evinrude 115 1977

They way you operate your boat has alot to do with performance. If your not familiar with how to properly trim your motor . I'd find a friend or someone who's operated a bass boat and have them give you a lesson or two. I had a buddy who bought a triton with a merc 225 on it. He kept complaining about his top speed, too slow. I finally had a chance to go with him . He was amazed at the way his boat took off when it was trimmed up. LOL. He had been running around with the motor fully down . <br /> Said several people were waving at him , just thought they were being friendly and waved back. LOL. He was just a plowin' besides being hard on his motor, it really sucked the gas.LOL Good-Luck,<br /> KYHunter

 

[G DANE]

Re: RPM/WOT Evinrude 115 1977

It wouldnt hurt to try raising motor and see if prop ventilates. Every hole you can raise motor will give you better hole shot with less bow-lift, higher top-end and lower fuel consumption. Just lift it till it starts ventilating in turns, then go a hole down again. Wont cost anything but work. Do a search on raising motor here. Many boats will accept antiventilation plate 1" or 1 1/2" above lowest point of keel with no problems, depending of what prop you re running.

 

[vano6990]

Re: RPM/WOT Evinrude 115 1977

Thanks OBJ. Sorry about that dhadley. If I had just followed directions from the start. And seems some of the RPM problem is That I'm probably not triming out enough. The last time I checked the spark it wasnt quite blue and snappy more orange and yellow, but the first time I tried there was no spark. This motor did die on me once and wouldnt start back up and that is when I was checking the spark and ignition system but didnt have a manual. I have not had any problems like that again and I didnt do anything to really fix it?? This was over 10-12 months ago.

 

[vano6990]

Re: RPM/WOT Evinrude 115 1977

Thank everyone for the help. I ran the motor last weekend and trimmed out more and what do you know the RPM jumped from aprox 5000 to 5500/5600 RPM. Will continue to complete all suggestions above.

 

[OBJ]

Re: RPM/WOT Evinrude 115 1977

Wonderful thing TNT.....ranks up there with sliced bread....... <br /><br />Thanks for posting back Flathead....nice to know when a problem gets resolved.

 

[KYHunter2]

Re: RPM/WOT Evinrude 115 1977

Yep,<br /> I love the way it sounds , when trimming up and a scootin'.<br /> Have fun Flathead !<br /> KYHunter

 

[Boilermaker]

Re: RPM/WOT Evinrude 115 1977

I was just wondering if you got that 500-600rpm "JUMP" all at once while trimming up??? Did you get a corresponding increase in speed??? A 500rpm increase should be a very noticeable speed increase.<br /><br /> If not, then you have just reached the trim point when the prop loses bite, thats when you need to trim down a little.

 

[vano6990]

Re: RPM/WOT Evinrude 115 1977

Boilermaker. Thanks for the question. I am confused If the prop lost bite wouldnt that decrease speed? It seemed to incease but on one trip across the lake it seemed just the tach moved and no noticible difference in speed (not like turbo or anyting). The tach does increase when I trim out. This bring me back to maybe another topic/thread but the motor has/does race. I throttle forward and it speeds up normally. Like one would expect. Then when the throttle reaches aprox 3000 RPM the tach shows the motor race/excellerate to like 4500-4600 then I can throttle more and it is normal again and I then can trim out and get per the tach the 5600 RPMs.

 

[Boilermaker]

Re: RPM/WOT Evinrude 115 1977

First, let me make one thing VERY CLEAR>>>most of the guys that have been answering you in this thread ARE EXPERTS! I am learning this as I go, just like you. I have learned a heck of a lot in the past 3 years by listening to guys like DHADLEY, OBJ, WALLEYEHED... ect. But they ALL are worth my respect and thanks for the many posts for us to learn from!!!<br /><br />These guys have done there homework! And a lot of these guys make there living as pro wrenches in this field.<br /><br />AS for loosing bite>>> if you keep rising the trim to the point that the rpm's rise>>>but you get no increase in speed, it is NOT what they are suggesting when they say shot for 5600rpm or higher. <br />You want to set the boat up to get these rpm's while still being "hooked-up" . Having the prop/engine/hull combination set up to get the most efficient power transfer from the engines rotation to the hulls foward motion.<br /><br />Think of a drag racing car with street tires. Hit the gas & the rpms rise and the wheels spin & smoke. Your getting the engine into its "powerband", but your not moving forward very well>>>a lot of wasted energy. <br />Put a set of slicks on the car, hit the gas & off you go! You may slip some at the start, but then you "hook up". If the gearing is right you go FAST & you don't over work the engine. ( Very over simplified I know, but it gets a good visual)<br /><br /> With your boat, the idea is to start out with the engine trimmed down, hit the gas, and as the hull comes up on plane, you start to feed in "up trim" until the boat becomes unstable, or you start to slip the prop to much.<br /><br />A sudden jump of a few hundred RPM's with little or no increase in speed is the prop starting to slip or "vent" as it looses grip. Think of this as a cars clutch slipping>>>More RPM's but no more speed>>maybe less! Waisted energy!!!<br />You might also notice that the steering starts to pull to one side, that is a function of the engine's torque, and now lose of it being applied to the water. <br /><br />I would figure going from 5000rpm, to 5600rpm should be close to 5 mph increase on your boat. If your not seeing an increase of at least a few mph>>then your just "spinning your tires" & slipping your clutch!<br /> <br /><br /> SORRY this is long>>>but I hope it helps you!

 

[Boilermaker]

Re: RPM/WOT Evinrude 115 1977

Flathead Hunter, it would be helpful to know the TRUE speed your getting & the pitot speedo is NOT an accurate gauge.<br />Pick up or try to borrow a GPS>>>Even the cheap hand helds give very accurate speed readings. You can then calibrate the paddle wheel speedo in your fishfinder>>a better gauge then the pitot tube speedometer.<br /><br /> ONE OTHER THING>>>If your gas tank is the original, built in tank, I would pull the "pickup tube" and check it. Most have a screen on the end to prevent picking up debris. You don't want to starve the engine for fuel>>>it gets ALL of its lubrication from the fuel>>>Run it lean & seize it / blow it up!!!<br /><br />I have been down the same road as you>>I have a 1971 18ft (17.5ft)modified vee hull runabout (very heavy compared to todays boats), with a 1978 Johnson 115hp. Mine is running 36/37 mph on my GPS & turning 5150/5300rpms. I'm still looking to get MY rpms higher. <br /> <br />

 

[vano6990]

Re: RPM/WOT Evinrude 115 1977

Thanks Boilermaker. I will get a GPS and pay more attention to what happens when the RPMs reach 5600 and post the results. <br /><br />How did you put your picture of your boat in this post?

 

[vano6990]

Re: RPM/WOT Evinrude 115 1977

Carb Kit is Bombardier #439076. Aftermarket Sierra #187046.

Where can I find the Bombardier #439076 kit? I have spent about 30 minutes looking and can only find the aftermarket. I would like the omc instead.

 

[ezeke]

Re: RPM/WOT Evinrude 115 1977

Any Johnson/Evinrude Bombardier Recreational Products (BRP) dealer in the world, including maxrules.com and ishopmarine.com can sell you a Bombardier #439076 kit.

 

[vano6990]

Re: RPM/WOT Evinrude 115 1977

Thanks.

 

[vano6990]

Re: RPM/WOT Evinrude 115 1977

Rebuilt the carbs. Found a mostly clogged high-speed orifice/tube. Cleaned them like new and reassembled. When removing the choke solenoid I found the ground connection was preventing the carb linkage from moving all of the way down. This was limiting the air flow into the carbs by probably 1/2-3/4%. Would the secondary still kick in to get WOT of 5600 as in my above post? If I was getting 5600 rpm before am I now going to be under propped? The boat was really hauling. I just did compression test etc with good results. Has the motor been lugging this whole first year of ownership?