ok just got a speedboat, im very mechanical minded and am fine with cars but boats baffles me, the outboard is a mercury 85hp lump, quite a few years old but that doesnt matter to much with boats as very little use.

were the hell do i start?
servicing etc

what to check before i take her out on the water (dont wanna break down)

any help extremely greatful

also boat has a speedo and rev counter etc, dont think there wired up were do they connect? boat has electric start with a key and a car battery etc

You want to get yourself the Clymer service manual. Bit like a Haynes manual only it actually contains useful information ;)

I suspect the speed sensor and tacho were attached to a previous motor - perhaps they swapped over outboards before they sold it?

Remember to winterise at the end of the season and keep spare spark plugs with you.

helpfull Taa but were goin out on the boat monday and would like to check it over day before

can anyone else help?

Won't be a lot of things to do to the engine whilst its still in water.
Servicing is much like a car. Clymer manuals are good as stated. It will have details of the wiring to check the speedo and revs link.
Servicing is usually oil change, plugs change, points gap check/change (unless electronic).
What is well worth checking is cooling system. The outboard motor will pull water straight from river/sea through a very basic filter. Check this is ok before pulling the boat out of water. Make sure that at idle there is a thin jet of water being squirted out the back which turns into a good flow with higher revs. Strip this system down when out of water, especially the inlet filter. It may pay to get a new water pump if you don't know the history of the engine.

Also worth while taking a repair kit with you when on the water, esp at sea (plugs, points, tools).

the boats on trailer outside, its had a new impellor and squirts water out fine on idle, although cuts out everynow and then at idle speed

Excellent American website at http://www.iboats.com , from this home page there are excellent forums including a outboard one which if you do a search you should compe across similar questions/answers...

Just a warning, dont run the engine on the trailer unless you have the correct setup to supply water to the engine. Running it dry will rip the rubber blades off the impellor.

The rest of it is all common sense servicing, might be worth changing the oil in the gearbox-at the propellor end, or at least checking the level. Good advice was given-check the plugs,or fit new ones and take spare ones too. Make sure the ignition system is reliable. Make sure you know the correct oil/petrol mix, I presume it is 2 stroke, or even that if it is oil injection that there is oil in its tank.

I should give it a good run before you go too far out to sea!

Les :)