How many hours is a 300xs good for?

[zx14]

before compression drops?

 

[HST4ME]

There are good ones and there are bad ones. The key to big block mercs surviving is even operating temps and good oil.....and the compressor not puking and spreading it's aids everywhere. There are many here in cold water Michigan holding their own at 500+ hours, and some that failed way way before that. Personally I hate the fucking things and am not sad to see them go.

 

[hallett21]

Got 700 on mine. Lost the compressor around 550. injectors were cleaned and she’s running great. I run 50/50 AV/91 and I run mercury premium 2 stroke oil.

Edit: 2004 motor 250 optimax xs


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[RCDave]

Earlier models had the compressor issues.

No problems with my 2015 with 80 hard hours. Only Merc racing 2 stoke oil in mine

 

[ONE-A-DAY]

AV gas, good oil and annual injector cleaning is the key.

 

[zx14]

Earlier models had the compressor issues.

No problems with my 2015 with 80 hard hours. Only Merc racing 2 stoke oil in mine

Earlier models had the compressor issues.

No problems with my 2015 with 80 hard hours. Only Merc racing 2 stoke oil in mine

whats considered a early model? 2007 to early?

I had a 300x on a 21 Daytona was not as nice as my other 21 with the 2.5 offshore. That damn 300x would shut off 2-3 times a day, park for few minutes and it would run just fine, nobody could ever figure that bitch out, sold it.

 

[zx14]

Does the compressor act as a blower?

 

[RCDave]

My understanding is the Compressor is for the high pressure fuel injection system.

Not sure what year the compressor design was improved but earlier ones were having issues with an internal part eating itself and sending metal bits downstream into the injectors...

 

[Croz]

Got 700 on mine. Lost the compressor around 550. injectors were cleaned and she’s running great. I run 50/50 AV/91 and I run mercury premium 2 stroke oil.

Edit: 2004 motor 250 optimax xs


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I bet that vector runs solid with that set up. I have a soft spot for OBs and want another one every time they fly by.

 

[hallett21]

I bet that vector runs solid with that set up. I have a soft spot for OBs and want another one every time they fly by.

Kyle just put a jack plate on it for me so it’s carrying the bow much better than before. It’s an honest 68mph boat with people and fuel.

Nothing like them. Love the way you’re 210 looks [emoji1303]


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[n2otoofast4u]

What about the 300X's?

What are the fuel and maintenance requirements on them?

 

[zx14]

What about the 300X's?

What are the fuel and maintenance requirements on them?

I only put premium in it and that expensive merc oil. Of another fun fact when I bought the 300x from dcb, the first one lasted 20 minutes, and granaded , crank broke in 3 places. Must have been a Friday build.

 

[ONE-A-DAY]

What about the 300X's?

What are the fuel and maintenance requirements on them?

On the X merc called for 93 octane which you really cant buy any more, so in mine I just run straight AV gas 100, its not much more then premium at $5 a gallon and worth the peace of mind. Less smoke as well.

 

[n2otoofast4u]

On the X merc called for 93 octane which you really cant buy any more, so in mine I just run straight AV gas 100, its not much more then premium at $5 a gallon and worth the peace of mind. Less smoke as well.

That's what I was afraid you were going to say. Ethanol free 91 is hard enough to come by here, 93 doesn't exist, and AV is only available 30 miles away. I run AV in the Hallett, but that's easy because I use it right near the airport, but we don't use the "big boats" over there.

Anyone making head mods and tunes to pull some compression and timing out to make them live on 91?

 

[Shlbyntro]

My understanding is the Compressor is for the high pressure fuel injection system.

Not sure what year the compressor design was improved but earlier ones were having issues with an internal part eating itself and sending metal bits downstream into the injectors...

The Opti's compressor is for the fuel injection and plays no role in forcing air to the engine.

The Opti's have a fuel injection system all their own. You have a standard fuel rail and injectors just like in a fuel injected car but the fuel rail is piggybacked onto an air rail. The compressor feeds high pressure air to the air rail. So fuel is injected into the air rail where high pressure air is then used to inject it into the combustion chambers.

Many early Opti's had a problem with water collecting in the lower air rail from moisture in the air (like your air compressor tank at home) many of those engines died because of this. But that problem had been fixed.

The most common reason for the air compressor itself to fail on these engines is overheating of the compressor. It is actually cooled by the water that flows to your "pee stream". Unlike other engines that are usually OK when the pee stream gets clogged, it is the Opti's Achilles heel. I'd personally choose a carbureted Black Max myself