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old 2 stroke engine

Yamaha 4 hp 2 stroke outboard. Hasn't been run in many years but was running fine when last used What would I need to do before attempting to start it?

Reply to
fred
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fred wrote on 11/07/2018 :

Easy job - take the head off and take a look at the condition of the bore(s). If that looks OK, drain any fuel, clean the carb out and its jets, air-filter, spark plug(s). Reassemble, add fuel and start it.

Reply to
Harry Bloomfield

I wouldn't go that far as you might need to / should replace the head / base gasket (if it has a separate head and barrel) and they may not be easily available, especially outside a complete gasket kit.

You can do that cheaply and easily these days with an endoscope that plugs into your laptop or smart phone. However, if you remove the plug and peer in the bore with a torch you might get a general idea of the condition and if you spray some light oil into the plug hole and then gently try turning it over by hand, you should get an idea if it's got any problems or not (and you might know if it was laid up properly the last time it was used and how / where it was stored etc).

Agreed.

It may not be necessary, easy enough to try first.

Yup. They often don't have an air filter as such or only have a course oiled sponge type that, if in good shape would just need rinsing out in paraffin and re oiling (engine oil will do).

Also check the lower leg / final drive doesn't contain any water and drain / re-fill with the right grade oil. You may need to test run it in water or it might damage the water pump impeller, if it's water cooled (and the chances are the leg would be, even if the cylinder was fan / air cooled).

I'd go for 50:1 2/ mix of an outboard 2/ oil, 10:1 if it was a British Seagull. ;-)

Cheers, T i m

Reply to
T i m

empty out all old petrol

wash out clunk or fuel filter if it has one

Fill with new petrol

Start. If it doesnt THEN start disassmbling and cleaning

Reply to
The Natural Philosopher

Many thanks for the informative replies. I think I'll try Tims way first and then go from there

Reply to
fred

In message , fred writes

Based on experience with Seagull outboards, I'd agree with advice to wash out fuel tank, carb etc. Check gearbox oil. Inspect plug, one brief squirt of 3-in-1 from aerosol can into plug hole then check for spark. If no spark, check magneto contacts.

If water cooled, find clean wheelie bin, part fill with water and try to start in that. Run slowly to clean out any old salt from waterways.

Let us know how it goes, as I have an old Seagull and an old Volvo Penta to sort out here.

Reply to
Bill

T i m formulated the question :

'Might', but probably not. I had several 2T's and regularly took the heads off to clean off the carbonisation and never saw a need to replace the gasket on a 2T, providing it was carefully refitted in exactly the same location as it came off. A 4T I would definitely replace the head gasket, because their gaskets are so much more complex.

Reply to
Harry Bloomfield

T i m formulated on Wednesday :

The petrol oil mix, will have evaporated out over the years, leaving a bit of a mess in there. Even stored for just a few months, the carbs can choke up on 2T's.

Reply to
Harry Bloomfield

But given that it may not be necessary to even disturb anything, why add more complication / risk?

How many of them were outboard motors OOI?

Funny. I've run many 2/'s over many years / miles and rarely done that. Maybe you were using the wrong lubricant or not running them hard enough?

The option to re-use gaskets on any machine can be down to their function (ignoring re-usable designs, like the rubber gasket type) ... if they are just to 'soften' a metal to metal contact and/or provide a set thickness spacer, rather than form an oil / compression seal and assuming the old gasket comes off cleanly in the first place etc.

Worth a go but again, rarely ideal (considering the above etc).

I *could* have re-used the thermostat housing gasket on the kitcar the other day but because I'm a good wrench, I made and fitted a new one because that was the right thing to do. ;-)

As are bigger water cooled 2/ outboard motors. ;-)

Cheers, T i m

Reply to
T i m

They can, but new petrol in there usually dissolves the gums. I've had a couple of clinks needing washing out and blowing clear, but by and large all is OK

They smoke on first start and the plugs may need a bit of cleaing after an hours running, but that's all.,

These are simple beasts really.

And I don't hold with taking them apart at the cylinder level. If they are corroded down the bores, its rebuild time whenever you discover it. Why not take the chance its OK, becase trying to start it wont wreck it beyond where it is now.

And you want be able to turm it over if its siezed anyway.

Reply to
The Natural Philosopher

Are you sure you aren't treating everone as yourself? What if the engine had been laid up properly and the carb / tank drained, what would there be to clean out? The OP didn't say it wouldn't start, just what might he check before trying to start it as it was running fine the last time it was used?

See above.

Or not, the many 2/ outboards I've had and used over the years that I just check over, fill with fresh fuel and have then start on the first or second pull and run as well as the day I last used them?

Even if I might use an outboard again next week, unless I was leaving it on the back of the boat for the period, I would typically run the carb dry because I would be putting it in the back of the car and not want petrol (or even fumes) everywhere.

But you are right and especially with more modern fuels with other additives, *if* the system was left full of fuel / fuel-oil mix for a prolonged period, you *could* get gumming etc (depending on the sensitivity or design of the engine / carb).

Our last 2/ motorcycle was a 2/ but autolube so (and sometimes was) left unused for many months, only to start and run on the first or second kick.

My little Yamaha 2hp 2/ outboard was often not run for *years* and would then start on the first real pull of the cord.

Cheers, T i m

p.s. I've also had quite a few 2/ model engines feel completely gummed up after a long period idle but then free quickly with a bit of fresh fuel and run fine once started. But again I didn't leave the tanks full of fuel after use.

Reply to
T i m

... Assuming it wasn't done when the outboard was last used ... ;-)

Yup. It could well have been 'dry stored'.

I'd see if it starts before doing that.

If it won't start and with a drop of fuel squirted into the plughole / inlet it won't start, check for spark.

Check.

Run slowly to clean out any old salt from waterways.

Might be too late if you are doing it *then*? ;-(

If laid up properly, check / apply gear oils, fill with fuel, enjoy. ;-)

Cheers, T i m

p.s. Take the Seagull prop off and check for the remains of fishing line on the prop shaft and output bearing. ;-)

Reply to
T i m

Personally, I'd whip the plug out, see if it turns over easily and if not pour in half a cup of oil, orientate the engine so that the top of the piston is horizontal, and leave it to soak for a day or two.

If it turns over, check the air cleaner and try it with a bit of fresh fuel and a new plug. Check that you have a spark first. You may be surprised how well it runs.

If it won't start, the carb may need cleaning out because of oil and/or dirt blocking the jets.

I wouldn't whip the head or cylinder off unless I could not turn it over at all.

Reply to
newshound

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