"Matt Lang" wrote in message
om...
Folks,
I bought a boat from an estate sale (so asking the owner is out of the
question). The boat comes with motor. Motor is a Mercury. On the
motor it also says 1250, 125 HP six, Thunderbolt ignition.
snip
Now I have a few questions... Hopefully someone can help.
The motor guy said this motor is **** because it has the hanging
ignition, apparently the rotor (he said) costs CAD 400 ... pretty
expensive I must say..
I have no idea - he may be right, but I'd find a different motor guy.
Now:
- If the rotor is really so expensive, is there another that fits?
Automotive?
Can't answer, but I'd get a second opinion.
- What gas/oil mixture does this motor run?
Call any merc dealer with the serial number in hand (or post here) to find
out what year and then you'll probably also be able to find out the fuel
mixture. That said, it's almost certain to be 50:1. Others know more about
this than I do. I know you ran it (probably with existing fuel?) and it
worked. But regardless, I'd recommend using fresh fuel and oil.
- What kind of oil should I put in the gearcase?
Marine gear lube available at any boat shop. I think it's something like 90
wt. oil. Comes in a squeeze tube, but there's also bulk packages. A tube
or two should suffice. The parts guy should be able to tell you.
- How do I check the waterpump (or impeller)?
You drop the lower unit. Generally, for a new (to you) engine with
uncertain history, it's best to just replace it, and then just do that on a
schedule - every year or two depending on usage. The work is in dropping
the lower unit - and the part is relatively cheap. Therefore, it doesn't
make an awful lot of sense not to just replace. If you're not into the
mechanics of doing this, it's not a very expensive thing to have a shop do
for you.
- What compression should this motor have?
This is an interesting question - tough to get a spec for, in my experience.
I have a 20 year old Johnson V-6, 10 yer old re-build and a 35 year old 10
hp kicker, no rebuild. What I've been told is that anything from 90s to 120s
can be "normal" or "OK", but it's more important that they are consistent
from cylinder to cylinder. For example, my V-6's cylinders have pretty low
compression (90s), but are consistent. The motor runs great and the
mechanic says it's "OK". I have no idea if it would be more powerful or
otherwise better with higher compression or if that is just what it has
always been.
My little kicker, has about 125 in each cylinder. Also runs great.
- Is this motor really garbage? Ok it has no power trim/tilt .. but
aside from that?
My opinion? if it runs well (sounds like it does) and if the compression is
good (consistent), it is a good motor. I'd find a mechanic who's not
prejudiced against it and have him give it a going over - he can also show
you lube points, and give you tips on maintenance. You see very ancient
motors in every day service (I have two!!) and the bottom line, in my
experience, is how they work and how the compression and gear case is. I
think almost every thing else can be fairly easily upgraded, renewed, etc.
By the way, you might be able to add trim/tilt - either through a merc
product or an aftermarket product. Do a web search for options - two that
come to mind are Panther marine and CMC
- how does one decarbonize OB motors?
It may or may not need decarb. But it's easy (smelly and noisy, but easy).
I know OMC (maybe merc too?) makes a spray can decarbonizer. Instructions
are on the can. As I recall, the basic routine is to start the engine (in
the water or on hose) and let it warm up to operating temp. Then, while
it's running you spray the cleaner into the cylinders via the carb air
intakes. Then you let it sit for a prescribed time, and then run it again,
maybe repeat. Can't remember the details w/o reading can. Supposedly, this
can free up rings and improve compression in some cases -and is recommended
before going to more major fixes if compression tests are unsatifsfactory.
There is also decarb. fluid to add to fuel. And, I believe some of the
"premium" TWCIII oils have anti carb. additives.
- Is there anyhting else that I should do to this motor before I run
the boat? (aside from new spark plugs maybe) ?
Spark plugs are so easy and cheap, that's always something to do. I'd make
sure the cooling system (impellor, etc) is working - like said earlier,
maybe just change impellor. But if it's pumping water and staying cool,
(actually not exactly cool, more like "not hot"), I don't think a test drive
would hurt it if you want to do that before doing the impellor.
Of course, you want to make sure the steering system is sound and greased up
before taking it out, especially if you plan to go fast. I'd want to have a
back up for testing - either a kicker, a good paddle or a friend in another
boat (or available by cell phone).
I dont have much experience with boats and boat motors .. so I am a
little helpless right now...
Any advice is appreciated 
Hope this helps. My "impression" is that you might have gotten a
serviceable rig - since it started right up and runs. Other than the above,
there's really not much more than that!
HAVE FUN.
Grissy.
Matt