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Merc Optimax 135 HP 20042005

"Outstanding motors.

The e

"Outstanding motors.

The early Opti's (prior to 2001) had a few "bugs" in them, typical of any "new" product, but were ironed out and became a relatively trouble free motor.

A couple things to consider when you are venturing into a Direct Injected motor -

The Opti's are very hard on sparkplugs (and the plugs aren't cheap - upto 15 bucks a piece and you would have 6 of them) - it's not uncommon for them to be unusable after 50 hours of run time.

That is a result of the DI design used by Merc and Tohatsu (orbit or orbital) - which allows them to run low pressure injectors (better for the life of the injectors and the rails) but hard on plugs and as of yet there has been no solution to lengthen the life of the plugs.

You MUST use oil specifically designed for DFI models.

Of course again, it's more expensive (retails for 30-40 bucks a gallon) - but, since the design of the Opti allows it to run at upwards of 300:1, a gallon of oil will go as far as 2 or 3 gallons on a conventional 2 stroke which evens out the cost for oil over a season.

One other note on the oil system. It is not like any other oil injected 2 stroke. The oil and the gas never mix prior to the cylinder firing - so you can NEVER disable the oiler and run mixed gas.

Opti's are technically a 2 stroke, but do not confuse them with any 2 stroke you may be familiar with.

These are a high tech piece of kit that you don't fix with a screwdriver in the backyard.

These have an engine computer, a multitude of sensors, fuel and air rails, pumps, separators and two completely different injectors for each cylinder - so you require a diagnostic computer and a tech to undertake maintenance on these for many items (although regular maint can still be done "at home").

My rambling above is about as negative as I can get about these (and don't think that's too bad by the way).

On the positive side, given that their current competition is either other DFI motors or 4 strokes - they are just as quiet and have as good as or better fuel economy than any 4 stroke on the market today.

In terms of torque (for hole shots), high end speed, horses per pound etc etc they will kick the snot out of just about any other motor on the market today (yes, they are even superior to the ETEC's no matter how you compare them).

When thinking about longer term maintenance, a 4 stroke has 200 to 300 more parts on the powerhead than a DFI (the head is one piece with 6 injectors).

My opinion, you can't break stuff if it isn't there - so while parts are just as costly as any relatively new engine, there just isn't a lot to go bad.

So in the long run you would have a quiet, fuel effecient motor that requires little more than regular maintenance, but it is a little hard on plugs - can't ask for much more than that.

Would I hang a 135 Opti on the back of my boat - YES, without a second thought and would choose it over anything else currently on the market in that horsepower range."
 
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