Steps wrote: Not to use methanol fuels above a certain %, will also be in the outboards instruction manual... As per comments above dont use it.. slow death to the engine. Will the motor need a re-tune for 98? Yes. timing is very critical, the days of swing back and forth on a dizzy (4S)( same principle applies to any petrol internal combustion engine) or by 'ear' long gone pre 1980s Timing on modern outboards.. at least 90s up.. is very sensitive.. and not like your old magneto lawn mower or vintage motor bike. Get it wrong, can start stuffing pistons, over heat CD! and power packs... Again slow death.. Even back in the day, tune by ear, and or just swing on a dizzy, so many engines went down and usually got blamed on assembly or some other BS. Timing is a combination of cylinder pressure (not ratio) at point of ignition, and fuel octane, at given rpms and load....octane also determines the speed at which the flame goes across the chamber...higher octane slower speed. |
Kandrew wrote: 2 stroke motor have a lot less compression than 4 strokes, for this reason they don’t make use of the extra benefits of higher octane fuel. Increasing compression in a 2 stroke robs the engine of hp because there is only 2 cycles and the extra compression competes with the engine ability to reach TDC on the compression/ignition stroke. So there is no benefit in using 98 in a 2 stroke. As for timing, ignition timing can be changed on a 2 stroke, but dynamic or engine timing is set by height of the ports in relationship to the combustion chamber. No cam or valves. The problem with ethanol is all the plastic and rubber parts in the fuel system that ethanol eats. |
Pcj wrote:
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Kandrew wrote:
But at the end of the day my 115 opti runs fine on 91 and it’s heaps cheaper because petrol prices are just ridiculous at the moment. |
Pierre'o wrote: Hi guys, where can I get the best deal on two stroke oil? B and MD has 4l Valvolene for $59.99. That’s $15 per litre - seems v expensive? Can anyone beat this? Pierre |
Pcj wrote:
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e.m.p! wrote: mind if i barge in? I have some spare Motul DiJet 2 Jetski oil. Is that ok to use in my 30hp 2 stroke Tohatsu? Can't imagine to be too much of a difference |
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