Real answers about converting f75-f90 please?

[madharchod]

ok chief

your logic and my practicality ,both are same engines one with restrictor and the other one without,correct.both engines have the same ecu and one is programmed from its inception to run at 6000rpm being F75hp and there is the other engine with everything the same including the ECU and WITHOUT the restrictor being F90hp ,so what i do is remove the restrictor from f75 and the ECU being the same re-adjust to run at 6000rpm now since i have removed the restrictor and the ECU has re-programmed itself to being a F90 .as you have said yourself before that the EFI engines re-programmed them selves on load and it re-adjusts the airflow and gas intake .
So chief where is the BS ,mate i have done it iam taking from experience ,i wouldn't say if i haven't done it ,its working in FIJI on so many boats that i have changed no drama .if i happen to get to USA in near future i might do it and post a video or else if get to change another one soon i will document it before and after pictures and a full video of how its done

[rodbolt17]

your simply wrong.
the ECU cannot and will not "adjust" itself.
BOTH engines are rated at 5500 RPM with a max of 6000 RPM.

THE engine ECU has no clue of a mechanical restriction.

the ECU's are mapped a bit different.

in the field we cannot change,reset or reprogram the ECU map.

I spent 6 years in the US navy as a fire control technician.
my first 3 years all I did was advanced electronics schools.
I do understand ECU's and control unit mapping.

[boscoe99]

ok chief

your logic and my practicality ,both are same engines one with restrictor and the other one without,correct.both engines have the same ecu and one is programmed from its inception to run at 6000rpm being F75hp and there is the other engine with everything the same including the ECU and WITHOUT the restrictor being F90hp ,so what i do is remove the restrictor from f75 and the ECU being the same re-adjust to run at 6000rpm now since i have removed the restrictor and the ECU has re-programmed itself to being a F90 .as you have said yourself before that the EFI engines re-programmed them selves on load and it re-adjusts the airflow and gas intake .
So chief where is the BS ,mate i have done it iam taking from experience ,i wouldn't say if i haven't done it ,its working in FIJI on so many boats that i have changed no drama .if i happen to get to USA in near future i might do it and post a video or else if get to change another one soon i will document it before and after pictures and a full video of how its done

What you fail to understand is that the F75 and F90 do not have the same CDI (carburetor) or the same ECU (EFI). Neither the CDI nor the ECU will reprogram itself.

Yamaha engines run very rich. When you remove a restrictor plate, if this is what is being done, you might get a little more power but not the same power that you would get if the CDI/ECU was changed. You might also now be on the verge of damaging the engine due to a lean running condition.

Don't take my word for it. Look at the Yam parts catalog for the two engine types. I am posting it below to make it convenient for you.

[madharchod]

oh well
i have done it and if you cant accept like Always AMERICANS do WMD does exist this is working in Fiji and have put on 4500hrs on one motor and no problem
cheers

[99yam40]

Still does not mean you turned a 75 into a 90 just because you think and say you did. You have no proof of anything.

Just posting something on the web does not mean it is true

Most good mechanics from all different countries, not just USA, understand and use their common sense to figure these things out.

Seems if you have access to a computer to be posting this stuff, you could also look up part numbers to help back up some of your posting.
But then you would be wrong as other have shown

[mphelle8vld]

It's easier to think of it as turning a de-tuned 90hp back into a 90hp. Whether they used the non-mythical restrictor and/or ecu, I think it goes against the grain of most gearheads for Yamaha to restrict the air and fuel to the 90 in order to re-badge it as a 75.

[boscoe99]

It's easier to think of it as turning a de-tuned 90hp back into a 90hp. Whether they used the non-mythical restrictor and/or ecu, I think it goes against the grain of most gearheads for Yamaha to restrict the air and fuel to the 90 in order to re-badge it as a 75.

Which came first? The chicken or the egg?

Which came first? The 75 or the 90? Is the 75 a detuned 90 or is the 90 a souped up 75?

I am not saying that the 75 cannot be converted to a 90. What I am saying is that just removing an intake air restrictor, when clearly there are other differences between the two motor types, is not going to get the job done.

A gear head, Yamaha or otherwise, that cannot understand this is not qualified to hold a screw driver in his hand. This is done all of the time in the marine and other industry's.

A certain carbureted 260 HP airplane engine produces 300 HP when the carburetor and air intake system is replaced by a fuel injection system. More air, more fuel, different ignition timing equals more HP. What is so hard to understand about that?


Nascar installs a restrictor plate on certain motors with the necessary carburetor (now EFI), ignition and other changes and the motor produces less HP. Conversely, they take the restrictor plate off, make the necessary ignition and other changes and now the same motor produces more HP. What gear head cannot understand this? If he can't understand, he is not worthy of calling him self a gear head. Maybe he understands just gears and not motors.

[mphelle8vld]

It's easier for most people to think of it as turning a de-tuned 90hp back into a 90hp. Whether they used the non-mythical restrictor and/or ecu, I think it goes against the grain of most gearheads for Yamaha to restrict the air and fuel to the 90 in order to re-badge it as a 75.

[99yam40]

Yamaha and other manufacturers may de-tune a motor to meet the needs of some boats( lower HP rating) or other things with out having to completely redesign another motor.

I know they did it on the smaller motors like the 9.9/15 due to HP restrictions on some lakes.

But on the larger HP ones , boat hull HP max ratings is the only thing I can think of right now

Less engineering costs to cover more range of HP motors

[boscoe99]

It's easier for most people to think of it as turning a de-tuned 90hp back into a 90hp. Whether they used the non-mythical restrictor and/or ecu, I think it goes against the grain of most gearheads for Yamaha to restrict the air and fuel to the 90 in order to re-badge it as a 75.

Funny that folks would think that way. Yam for instance introduced the F200/F225 and then upgraded it to the F250.

Some of the smaller motors come out at the same time. So, is one a detuned version or is the other a souped up version? Only Yam knows.

[boscoe99]

After comparing a carbureted F75 with an F90, here are the differences that I noted. So, if someone is willing to change the carburetors and the CDI then it is possible to get 90 HP out of a 75 HP motor. Might be cheaper to sell the 75 and just buy a 90 however.

[Qwerty79]

Recently bought a boat with a Yama F80 2010.
Started googling on how to make it into a F100 and found this thread.
After my reasearch i have found out that there is no difference in the engines except for the intake restrictor.

Both engines have the same spare part numbers (even ECU) except for the INTAKE SILENCER ASSY (part number:6D8-14440-01-00) where the restrictor is.

Also talked to a guy who ran his F80 without restrictor last summer and no problems.

Have just removed the restrictor but havent started it yet.
If all parts are the same, can the engine get damaged by removing the restrictor?

Picture of it.

[almetelo]

Old thread... same wishes! I understand you and is nothing wrong on that if you do it the right way (IMO)

To start with... read all complete post and youŽll find the facts... not our opinion!
ECU parts are diferent and not the same like you stated...
Have a look



I donŽt have experience with F80 to F100 EFI motors but I have it with F50 to F60 EFI and I'm sure that works the same way.
My experience on F80 to F100 are just on carbureted models.

Many people claim that convert a F50 to a F60 is just remove the air plate, like you expect it from your F80 to F100 no... its not true.

My cousin have a 2007 F50 and after remove the plate the gain was 100rpm's and maybe 1 knot or less.
With a F60 ECU and without air plate restrictor gain was +/- 500 rpm's and cant remember speed gains.

Last year promissed a video showing the diferences and I did it but the day I made the video as so windy and the hull was full crusties and I donŽt posted the video but in a couple of months I'll do another one with cleaned hull on a good day.

If you remove the air plate youŽll be or can be running to lean and risks you can read it on this thread.

Want convert it to a 100 buy a ECU
If you donŽt belive on US (most of us...) find someone with a F100 and ask the ECU loaned for a test than let us know what you figured out.

On my region was a guy selling a F80 ECU after buy a F100 ECU to convert is outboard

[Qwerty79]

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

[almetelo]

I belive it can be remaped but I dunno

who or where I donŽt know but IŽm almost sure you need a F100 ECU anyway to copy data to your ECU as this ECU re maps are not common if where already done or possible (at least that I know)