Real answers about converting f75-f90 please?

[almetelo]

I donīt know much about ECU remaps

On auto industrie German cars heard are relatively easy to remap while on Japanese car is hard to do it...
But I donīt know much about car tuning as wish my cars to last... and take your ECU to someone without experience on outboards remaps can end killing your ECU (maybe not)

[boscoe99]

Your right, not the same. Missed the one digit difference.
Is it possible to reprogramme?

Possible? Absolutely.

Cost effective? Who knows.

Who has the time, resources and expertise to reprogram the ECU? No one that I know of.

I am still looking for the fountain of youth. I need it more each day. I suspect my odds of finding it are the same as the odds of you find someone to reprogram your ECU.

[rodbolt17]

here in the states a place called hydro-tech does some ECU remapping.
dunno about the F90-F100.

I quit the hot rodding thing a long time ago.
now I put it back together just as the factory did and it runs well and everyone is happy.

my service manager has a VF250 he was thinking about having the ECU remapped, however this would void his warrenty.

so if Yamaha wont warrenty a modified motor, why would I????

[zenoahphobic]

I've been following this thread.
It seems to me that perhaps not enough recognition has been given to the immense differences between what is found available on our planet, that has fuelled some considerable argument between individuals. This is afterall a global forum. Not helpful resorting to "must not be qualified to hold a screwdriver" or such comment. (Afterall the engine designers may not be qualified in the way implied!!)
I must say I do not find anything posted much unbelievable, although prima facea might be at odds. Engines are supplied greatly varied from country to country and so is the fuel - and often details are not specified and deliberately hidden!
Therefore differences will be there.
I have two comments:
Has anybody actually measured and mapped actual HP (at various revs also)? Surely all engines could not be that well engineered to meet the exact (so nicely rounded to) HP. (I have been wondering since a kid about this, I thought how cleaver exactly 50, 100, 150, 200....HP, and I couldn't understand how one manufacturer could claim e.g. their 100HP motor is more powerful than So and So's 100HP motor) There is cheating, some fall short of the mark more than not, only sufficiently near the value for the manufacturer to place a particular engine within these simplified categories). Similar to where capacity (litres, cubic inch) is used to describe power. Any mods to an engine alters HP (torque whatever) through out the rev range.(I might add it is a mystery to me why it is believed that a engine must be propped at maximum revs, at maximum HP?)

And secondly same goes for fuel, what is in it varies. There is no such thing as Gasoline etc. - components vary and burn differently! So I believe it might be oversimplification to exactly put a range of air to fuel ratios, as history alters with evolution of motors. I am sure the air to fuel ratio for "gasoline" is only for the purposes of a comfortable safety margin to meet current designs and makeup of engines. In physics, chemistry or call it what you like, it is possible to combine anything given enough heat, pressure etc. So it may be possible to add a lot more air with a fixed amount of "gasoline" and also get out more energy. This is really used as power to create greater pressure (or volume if you like). It is a pity that engines only use this part of the energy and that heat energy is wasted. And we still use some form of heat to set this process in motion (latent heat for diesel, and electrical spark for "gasoline").

[ausnoelm]

If it is a mystery why an engine is propped to achieve max recommended RPM, then you need to do a lot more googling before rash statements about gasoline and so on are sprouted.

[zenoahphobic]

Ausnoelm, tell me why.

From my reading it seems there are only two reasons:
1. It is simply a waste not using all available HP
2. Only anecdotal evidence that outboard engines can blow up! Not really explained why this should be so other than claims of extra stress on the engine. Not denying that there could be damaging stress leading to increased wear in some situations. But simply WOT full load should be able to applied at any RPM, afterall increased RPM and increased HP always equals increased stress. For an engine to fail at lower stress means that it simply was not built strong enough.

I don't understand though the relevance this has to, or indeed what are my "rash statements" in regard to gasoline are? Please tell me

[zenoahphobic]

Can't post but if successful, my friend has 115 Merc that has same block rage from 75Hp to 200Hp!!! Price always increases with increase in Hp, just marketing strategy

[rodbolt17]

mostly cause there is NOT a MAF sensor on the F75-F90.
in fact NO current F Yamaha uses MAF.
can it be converted, probably but as the US has some EPA and USCG regulations aint no way I would do it on a customers engine.
there is also the legal liability about modifying an engine that may then be more HP the the hull rating plate.

kinda like the old 115-140 tohatsu.
only difference was the top carb and then only the throttle stopper.
a careful bend of the stopper increased power from 115 to 140.
that was measured with an IDC dyno back when I owned it and worked for a tohatsu dealer.

so can it be done,most likely. let us know how it worked and what it costs.
at a minimum a new prop (assuming its propped correctly now) and a new ECU.

[zenoahphobic]

Same block perhaps, but the pistons and cams are different, as would be the starter and coils likely.

If I didn't have difficulty posting on this computer, I would also have added that there is some upgrading of parts along the way but not hand what chages where.
So in essence 99yam40 might be a bit harsh if he was critisizing your response to mine.

This business about MAF (whatever), someone (not the OP) has now descided one exists, so the argument should be focused around whether the system on this engine can actually increase fuel delivery.

[greasyshaft]

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[rodbolt17]

actually seastars, its you that are clueless.
google the difference between MAF EFI and speed density EFI.
Yamaha uses the open loop speed density which does NOT use MAF.

the ECM cannot do millions of calculations per second, its not programmed to do stuff in the megahertz range.

years back it was in the 64/sec range.

but the ECM cannot and does not measure MAF nor O2 on the Yamaha 4 stroke EFI motors

maybe oneday,when outboards use catalysts.

[zenoahphobic]

And Seastar your quote didn't even say what you wrote

[greasyshaft]

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[rodbolt17]

actually, double clocked with an electron counter.
keeps the white noise from the electron wobble out of the picture.

[greasyshaft]

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