TOPIC: Couple Merc Questions ....can u help?

Wondering weight diefference beteween an 85hp (4cycl) and a 90hp (6cycl) ? wouldn't think much but figured I better ask before I get my mind set on something.

also...
Have a Merc 65hp Serial # 2108797... i picked this up last year as possible redo.
I check compression which was low in all 4, had been sitting for a long tiiimmmmeeeeee..... anywy I had checked spark on it when testing compression, it had it...i recently played around with it, and now nothing?
Wondering where to start on this model of ignition sytem?
Not sure how the mercswitch works but it looks like its not even hooked up?

looking for help on either question....thanks in advance.

The 850 4 cyl and the 90 6cyl (1965) are a lot closer in weight than most people would think. The 850 uses the newer mid section that is slightly heavier. And the 850 and 1500 share most everything if that puts it in perspective. Chop 2 cyls off an 1500 and you have a 850. The 650 also shared all the same parts as its bigger 6 cyl brothers.

I bet the 1965 900 only weighs 30 lbs more than a 4 cyl 850. Possibly less.
Conrad

thanks conrad.....I have a '77 15' runabout open bow..its rated for 100hp...currentl running a 50hp....
with 4 adults the 50 is a bit under powered, and pulling tube..same deal. I found a 90hp 6cycl. near me and kicking in my head to pick it up to repower it....BUT..I already have an 85hp which I believe would be ok too...talking 5hp i know...but thought that tower would be cats meow..........

I run a 73 15 foot Marlin with a 90hp inline 6 and what a difference compared to my other 15 footer with a 85 hp merc.The 90 seems to have alot more torque (snappy).I dont know what RPM the 1965 90hp is but my 1978 runs @ 4500 to 5000rpm as for the 85hp runs @4800 to 5300 RPM.

The 850 is a great motor and is more modern than the 90. The 90 has points and can be a bit harder to tune. But the 90 is 90 cubic inches and that 850 I believe is 66 cubic inches. Cubic inches help move mountains. I think the 90 is rated around 5200 RPM and the 850 may have been rated at 5800 rpm.

The 850 makes its hp up high and the 900 makes it lower and will offer more torque. I bet they will both run fairly close to the same speed, but the 900 will out tow it for tubing and heavy loads.

Conrad

fixitdaily. Your 90 looks to be the newer late model L-6 that was 99 cubes. yes even more torque than both the 66 cube 850 and the old 90 cube 900.

Conrad

Matt what 900 do you have ? the old 1965 one with chrome trim ? or the newer 1980's 900?


Either one is better then the 50 and the 85.
Conrad

I weighed both motors (both had power trim) and the difference was about 35 LBS.

very good! Id run the 900 then whats funny is the late mod 900 and a 1500 weigh the same

milkdud wrote:

Matt what 900 do you have ? the old 1965 one with chrome trim ? or the newer 1980's 900?


Either one is better then the 50 and the 85.
Conrad

Conrad:
I don't have a 90hp, I happened to stumble across a guy who has one, along with a Sidewinder Lopro that need some major TLC.
Mu 15' TriHulls 50hp is ok I & I enjoy it.
The other day I got to ride in one of my dream boats GT150, 85hp Evinrude. Talk about popping out of the water....I loved it, not sure if the tri would be the same....that 85hp compared to 50...wow!
I have been hunting forever for a project boat to tackle that can handle some HPs but have been really unsucessful..either priced too high or need way toooo much work and high priced !! I don't have luck like neil....the GT i rode in...garage find the guy paid 2g for it....been sitting for 13yrs in the garage, new trailer 2 yrs ago....and motor had been rebuilt sometime w/ bigger pistons...told my friend he did good!