Yamaha 60 FETO (1999) performance upgrades. 90hp carbs

[timberman123]

Hello all,

Im new on this forum and as 60 yamaha 2-stroke owner looking for some performance upgrades I have some question. Perhaps some of you could advise me.

I like to upgrade the 60 FETO (1999) autolube engine with the kit from Hydrotechmarine (https://shop.hydrotecmarine.com/product.sc?productId=114). This fall I like to purchase this kit and install it in the winter.

On my 60 FETO autolube I have square bowl type carburators, I recently bought a set of 90 Yamaha carbs (also square bowl type with elec. prime start). I also have a set of 70hp carbs but those are the round bowl and without the electric prime start function. Are the 90 carbs overkill or are they good to use with the Hydrotechmarine kit? Can anyone recommend the Jet sizes I should use for the 90 carbs?

Ps: I contacted Hydrotechmarine and they replyd me they do not now what jet sizes to use for the 90 carb.

Thank you all in advance! Tim

[CRH1]

I have a 50HP 2-stroke with the square carbs, not sure if the 50 and 60 are the same block or not. I installed 70HP carbs and this is not simply a unbolt the stock carbs and bolt on the larger carbs. You will have to grind some metal off the larger carbs, not a massive job but also not plug and play. As far as the proper jets, what i did was go to Iboats.net and look at the parts catalog for the various HP motors and you can get a good idea on where to start with your jetting. Obviously start with too large and work your way down in jet size, much less expensive that way!!

[Capt Fin]

I have a 50HP 2-stroke with the square carbs, not sure if the 50 and 60 are the same block or not. I installed 70HP carbs and this is not simply a unbolt the stock carbs and bolt on the larger carbs. You will have to grind some metal off the larger carbs, not a massive job but also not plug and play. As far as the proper jets, what i did was go to Iboats.net and look at the parts catalog for the various HP motors and you can get a good idea on where to start with your jetting. Obviously start with too large and work your way down in jet size, much less expensive that way!!

I am about to do the same, putting a set of 70 carbs on my 50. Do you still run the oil injection system? I'm afraid of grenading my motor with the added air/fuel mixture.

[CRH1]

Yes sir, have not done anything to the oil injection system and have had no issues to date. Have had modifications done to motor for several years with probably a hundred hours.

[Capt Fin]

Awesome, that makes me feel a lot better. I think I'm going to start with #150 mains and probably end up around #145. I'm going to mill the carb manifold to port match the 70s and open up the reed cages some and see what happens.

[Capt Fin]

Also, CRH1 what all do you have done to your 50 besides the carbs? And how much of a difference has it made?

Sorry for hijacking your thread timberman123.

[CRH1]

I have shaved head, got around 145 PSI compression, Chris Carson reed valves and a Hydrotec tuner. As to the difference it made, I gained 2 maybe 3 mph from this and a few hundred rpm. Do have more holeshot which is nice. My boat is a 17' center console and rated for a 90, so every little bit helps with a underpowered rig. You will need to port match the intake to the larger carbs, also I did have to change the pilot jets to get a better idle. It idles pretty good now, but not as good as a bone stock.