Whats differencem between 115 & 125 Evinrude?

[John Bett]

Kindly requesting information from knowlegable person about the difference between older (70-72) Evinrude 115 and 125. My literature shows the displacment to be the same at 99.6 cid. Is there a difference? Thank You!

 

[rodbolt]

Re: Whats differencem between 115 & 125 Evinrude?

10 horsepower

 

[DHPMARINE]

Re: Whats differencem between 115 & 125 Evinrude?

Well said rodbolt.But is that at the prop or driveshaft ? GRIN Top,bottom,front or rear ?<br /><br />I can't give you an answer Johnnnn,that is specific to your engine.The difference is more than timing and adjustments,and probably more than jets.<br /><br />I tried to do this for a customer years ago,maybe a 1978 115 to a 135.We changed jets,exhaust covers and a whole much more,ran worse. there are so many differences,we gave up.Last thing we noticed,but he couldn't afford,the carb body venturies were larger.<br /><br />so it's not an easy answer.If you had both part books books you could trace it down,and it may even include engine mount changes.then try to locate all those parts.<br /><br />Sorry to be so long,but another thought... The engine/gearcase et al is pretty old,and you want to put more HP thru it ?<br /><br />DHP just my thoughts

 

[jimmbo]

Re: Whats differencem between 115 & 125 Evinrude?

The 1969 - 70 115hp were 96.1 cid, in 1973 the 99.6 block was used for the 115hp. The 1972 - 72 125hp did use a 99.6 block, but these weren't the same blocks that were used for the later 99.6 cid engines

 

[ledgefinder]

Re: Whats differencem between 115 & 125 Evinrude?

The 1969-72 V4s (85/100/115/125) have a different ignition system (battery-powered VD), and a hydroelectric shift lower unit. The bore sizes are 3 & 3/8 (85/100), 3.44 (115) and 3 & 1/2 (125). The 115 was the big gun from Evinrude/Johnson in 1969 & 70 (they made a limited edition 1968 115 as well). In 1971 & 72, the 115 wasn't made, and the 125 was the hottest you could get. The 125 was the first 3.5" bore motor OMC made. From 1973 on, 3.5" bore was very common in OMCs (115/135/140/150+V6 & 1979+ 85/90 hp). <br /><br />The 1973+ V4s have a completely different self-energized ignition, and mechanically-shifted lower units. The 115 re-appears in 1973, and goes on to become one of the longest-running, most popular outboards made. For saltwater use, on a bigger hull, their reliability is near-legendary; if we don't get our s**t together, one day we will think fondly back on when the US still made products like this motor.

 

[ledgefinder]

Re: Whats differencem between 115 & 125 Evinrude?

I should also note that, as the years slip by, the battery-powered CD 1969-72 V4s are turning out to idle better. We've had a number of complaint here on starting and idling of the later V4s, particularly 1973-77. I've quite a few hours an a 1975 115 and a 1974 115, and not so many but a few on a 1969 85 and a 1971 125. Both battery-CD V4s fired instantly cold, and idled dead slow; the later motors did the usual games when cold. <br /><br />The 1974-5 115s would occasionally stall when running the rope around to a skier; the old 85 I could send Grandpa out to troll dead-slow all morning without a complaint (I think he might have been asleep anyway). The 1969-70 115s and 1973-77 115s were dead even on my test prop (+/- 5400 rpm on a 85/100 4800 rpm test prop).

 

[jimmbo]

Re: Whats differencem between 115 & 125 Evinrude?

The 1968 115hp was based on the 89.5 cid block

 

[rodbolt]

Re: Whats differencem between 115 & 125 Evinrude?

DPH<br /> thats 10 at the loose nut behind the helm <br /> sorry for the short answer. I just could not resist.the moral here is dont even think about modifying it for 10 hp by swapping the 125 and 115 parts around

 

[John Bett]

Re: Whats differencem between 115 & 125 Evinrude?

Thank you all for the valuable wisdom and knowlege, John

 

[mnw001]

Re: Whats differencem between 115 & 125 Evinrude?

Hey ledge <br />I have a 73 135 evi that seems to be in great shape 145-150 compression and runs great.Would you put that in the same dependability group as the 73 115..

 

[ledgefinder]

Re: Whats differencem between 115 & 125 Evinrude?

Like a farm tractor, all of them will run WOT 24x7, if they're properly tuned and in good mechanical shape. That said, the 135 is more highly tuned than the 115 (they're the same displacement), and less forgiving of being out of tune. <br /><br />You probably already know this, but make sure the carbs are clean internally, and that you run fresh, clean gas. Two-stokes heat up when run lean. If one main jet clogs, that cylinder can run lean while the others push it along. Fairly common when someone starts using a motor that's sat for a few years with old gas in the carbs.<br /><br />Don't lug the motor, prop it so it turns 6000 with an average load. I'd de-carb the engine pretty thoroughly, if you haven't already. The 135 has a tapered top ring/skinny top ring land that seems prone to breaking, maybe when gummed up. [Same Dyke ring design that works fine on motocrossers & chainsaws.]