longy509 Posted December 30, 2015 Share Posted December 30, 2015 Hi i have a 2004 115hp 2 stroke Tohatsu and i was reading that by advancing the timing 2 degrees and bending the throttle stop on the top carb out of the way that i would then have a 140hp motor before i give this a go my question is would there be any noticeable performance benefits in doing this or would i just be wasting my time and chewing more fuel. Link to comment Share on other sites More sharing options...
Fab1 Posted December 30, 2015 Share Posted December 30, 2015 Hi i have a 2004 115hp 2 stroke Tohatsu and i was reading that by advancing the timing 2 degrees and bending the throttle stop on the top carb out of the way that i would then have a 140hp motor before i give this a go my question is would there be any noticeable performance benefits in doing this or would i just be wasting my time and chewing more fuel.My advice just quietly,leave it as it is. Link to comment Share on other sites More sharing options...
antonywardle Posted December 30, 2015 Share Posted December 30, 2015 so basically someone is telling you that the 115 is a de-tuned 140? google seems to agree with you The bore and stroke are the same so the timing makes the HP difference. Apparently a dealer can also do it for you. Link to comment Share on other sites More sharing options...
longy509 Posted December 31, 2015 Author Share Posted December 31, 2015 (edited) Ha i Know where your coming from Fab if it anint broke dont fix it but sometimes its just to hard too resist. Yeh antony that's what iv read but im not sure whether there would be a noticeable difference with the extra 25hp and if there is difference where would i notice hole shot or wot etc Edited January 2, 2016 by longy509 Link to comment Share on other sites More sharing options...
longy509 Posted January 18, 2016 Author Share Posted January 18, 2016 Anyone else got any input on a 25hp increase Link to comment Share on other sites More sharing options...
stevefish Posted January 18, 2016 Share Posted January 18, 2016 (edited) Is it the carbys as well?I understand my 40hp is the same block as the 50 and 60, but it's in the Jets. Never looked too far into it as I'm on max hp anyway Edit, punctuation and context Edited January 18, 2016 by stevefish Link to comment Share on other sites More sharing options...
DrownNprawns Posted January 18, 2016 Share Posted January 18, 2016 In the early models it was the reed valves that was the main difference Sent from my SM-G900I using Tapatalk Link to comment Share on other sites More sharing options...
bessell1955 Posted January 18, 2016 Share Posted January 18, 2016 Do we have a Marine Engineer as a member or sponsor? I am sure they will know the answer Link to comment Share on other sites More sharing options...
JimT Posted January 18, 2016 Share Posted January 18, 2016 (edited) most engines are slightly "detuned" by manufacturer for reliability and tolerances in manufacturing. You almost always can find a sweet spot in advancing ignition timing but there is a fine line between the sweet spot and trouble and is particular to each engine so what works on one may be fatal to another. In other words a good "tune up" will always help but needs to be done by a qualified person. eg on a road vehicle a dyno tune where the computer parameters can be fiddled nearly always ends in a excellent result in the hands of a good technician. Jim... Edited January 18, 2016 by jot Link to comment Share on other sites More sharing options...
longy509 Posted January 19, 2016 Author Share Posted January 19, 2016 Cheers everyone Link to comment Share on other sites More sharing options...
jimg1au Posted January 19, 2016 Share Posted January 19, 2016 i had twin 115 suzikis on my shark cat 140 were the same bore and stroke i can tell you the difference in the old v4 johnos 85hp and 140hp same block older brother was omc master tech he built a cracker of a v4 50kns on a 5mtr fishrader quinnie 1 different exhaurst between 85 90 100 125 135 140 2 different carby jetting you cant make hp with out burning fuel 3 different ignition advance its all about fuel in and exh out my 1994 4cyl merc runs on 2 cyl at idle to pass emmision stds then clears out a 2500 rpm there are lots of outboards with the same bore and stroke just different parts to make them more powerfull and more thirsty hope this helps Link to comment Share on other sites More sharing options...
longy509 Posted January 26, 2016 Author Share Posted January 26, 2016 Cheers everyone i might wait for the next service and see what my mechanic rekns Link to comment Share on other sites More sharing options...
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