Mercury 100hp

[khc1970]

I have a Mercury 100hp year 89/90 outboard on my fishing boat.
I want to know if it is a 2+2(run on 2 cylinders up to 1800rpm, then the rest kicks in above that)? From iboat.com, it seems to suggest all 100hp mercury in 1990 are 2+2, but when i asked 2 mechanics over here, they have never heard of the 2+2. One swears on the only engine which uses 2+2 is the V-max.

Thanks in advance for any suggestions

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[bruce]

could not find anybody over here either, most laughed,

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[jfm]

Most of the inline 4s (ie the series that replaced the inline 6)from about 1990 onwards were 2+2. I have a 115hp 1998 and 125hp 2002, they are both 2+2. It's certianly not true that only the v-max are 2+2

Anyway, you can easily tell as you drive the boat. When the second 2 kick in there is a big burst of power. In fact I hate the damn thing becuase I can't hold the boat just on the plabne at say 15knots. She either runs on 2 cyl and sinks off the plane, or runs on 4 cyl and becomes a white knuckle ride. Feast or famine. If you cannot feel the step change in power, your motor is not 2+2

You can get good info on mercs on some US boards, or ask at oldmercs.com (grubbs marine website)

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[Howardnp]

I think you have just answered a query I have with my 135 Mercury (97/98)!

There doesn't appear to be a smooth progression between trolling along and then on the plane and white knuckles.

To gradually increase speed is almost impossible and to come down in speed but stay on the plane is the same, suddenly dies and you slump in the water, a little throttle tweak and back up you go.

I had thought it might be a jet problem but this thread has given me another avenue to look down. Thanks

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[jfm]

Yup, that's it. AFAIK, it's not fixable. No point in meddling. Your engine is working fine.... well, as the designer intended.

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[Rum_Pirate]

Give an email to

George_Alvarez@mercmarine.com

He is based in Miami and is very knowledgable regarding Mercury engines.

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[khc1970]

Thanks to those who replied, I'm pretty confident it's a 2+2.

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