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Old 11-06-2020, 10:01   #1
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Starting Tohatsu M9.8 2 stroke (sat for 2 years)

Hi all,
have an engine that's not been started for 2 years in the locker of a boat I've purchased. I've not tried starting it yet as I'm not 100% sure of the procedure. I'm thinking change the petrol for fresh, add some throttle and pull the cord (with the prop in water), however I'm wondering if that could cause any damage. Anyone with experience got advice on what I might do before pulling the starter cord ? Looking under the cover all looks clean bar the (what I assume is) the fly wheel which has started to rust quite badly. Obviously I could pay a mechanic to do this but I'd rather just try myself.
Appreciate any feedback.

Gary
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Old 11-06-2020, 10:10   #2
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Re: Starting Tohatsu M9.8 2 stroke (sat for 2 years)

The fresh fuel is a definite - the old gas has lost its volitility. Remember the 2-cycle oil. Getting the old gas out of the carboretor can be a bear - the drain on the carb bowl may be hidden. Then, pull it through a few times to make sure that all is smooth inside and to get some oil on the cylinder wall, and go for it.
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Old 11-06-2020, 10:14   #3
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Re: Starting Tohatsu M9.8 2 stroke (sat for 2 years)

If that doesn't work, it's time to remove the carb and clean it, replace the sparkplug, and all the usual "!@#$ motor won't start" things. Storage should not have created problems outside this realm.
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Old 11-06-2020, 11:30   #4
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Re: Starting Tohatsu M9.8 2 stroke (sat for 2 years)

Many thanks sounds good. I'll let you know how it goes.

Gary
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Old 11-06-2020, 12:05   #5
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Re: Starting Tohatsu M9.8 2 stroke (sat for 2 years)

Good advice above. Don't forget the 50:1 oil mix.

I have that model and it's the best outboard I've ever owned. Purrs like a kitten at idle and is smoother than a 4-stroke all the way up the power band. About the same loudness of a 4-stroke, but 40% lighter (59 lbs vs. ~100 lbs). It's a gem I'll never sell... If I get out of boating before I die I'll give it to someone I like who will appreciate it.
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Old 11-06-2020, 12:16   #6
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Re: Starting Tohatsu M9.8 2 stroke (sat for 2 years)

Depends on how anal you want to get. I’d at least once I got it running change the oil in the foot and remove it and get a look at the impeller, and honestly if I did all that, I’m putting in a new impeller and keeping the old one as a spare if it looks fine, “rubber” seems to harden as it gets old and loses its flexibility, so even if it looks fine it may soon break.
I like to turn off a two stroke with the choke personally I race it up some and pull the choke, that pretty much floods the motor, the gasoline evaporated and leaves the oil behind as it doesn’t evaporate.
Also remove the prop just to ensure you can, grease the splines and out it back on, after it’s been on for a few years they can be enormously difficult to remove.
Long ago we ruined a foot trying to get a prop off that had never been removed.
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Old 11-06-2020, 12:19   #7
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Re: Starting Tohatsu M9.8 2 stroke (sat for 2 years)

Really good engines! Takes less than a minute to pull the carb. Open the carb, clean the gunk out of the bowl. There is a rubber plug covering the idle jet. Easy to remove both jets and check for dried up gunk (varnish deposits). No reason not to try to start it first but will probably need to clean out carb. You spill less gas if you do it first.
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Old 11-06-2020, 12:36   #8
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Re: Starting Tohatsu M9.8 2 stroke (sat for 2 years)

I've got the Tohatsu 4 HP and 40 HP four strokes. Love them.

If you are going to store your M9.8, consider this alternative to a64pilot's good words: while running, turn off the gas, so the engine empties the carb bowl. Pull the plug, spray in some light oil, and plug it up again. Or, do as a64pilot suggests, and then drain the carb bowl. Either way, no old gas to deal with next time, and the cylinder wall is oiled.

Having a bit of old gas in the tank can be dealt with after storage by pouring in fresh gas on top of it - the volitility of the mix will be OK.
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Old 11-06-2020, 15:22   #9
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Re: Starting Tohatsu M9.8 2 stroke (sat for 2 years)

For storing I would certainly fog the cylinder, I kill them with the choke as a matter of course, sometimes it may be a week or more between uses and it can’t hurt.
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Old 11-06-2020, 16:16   #10
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Re: Starting Tohatsu M9.8 2 stroke (sat for 2 years)

Take out the plug and get some sort of oil into the cylinder, then pull the cord a bunch of times to spread it around. I'd take the float bowl off the carb and inspect for grunge before fueling it up. A can of carb cleaner on hand would be great. If bowl is full of grunge, time to pull the carb and blow out all the jets and passages. This is a one to two beer duration job.
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Old 11-06-2020, 18:58   #11
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Re: Starting Tohatsu M9.8 2 stroke (sat for 2 years)

I just bought a 17' Whaler with a Yamaha 90HP 2 stroke 2 days ago. Seller said he put it away with Stabil. Yeah OK.

The gas in the tank was urine colored so I drained it all. Then I unplugged the fuel line leading up to the carbs. Put in fresh fuel in tank and pumped the primer bulb until clear gas ran out the line. Removed all 3 carbs and varnish in float bowls. Cleaned that out, and then carb cleaner spray. Put it all back together and she cranked right up. It's a good idea to pump the fuel line to be sure you get rid of all old gas in the lines and filters.

The other checks like oil in the leg (clear or milky), spark plugs are a must. Once you do get it running check to make sure it's pumping water out the pee hole.

Added to the standard fogging engine stuff, I also spray some corrosion inhibitor all over the engine under the cowl. That will keep the rust away. I use Fluid Film on my diesel but it's a bit thick for an outboard. I used CRC on the outboard, basically coating everything.
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Old 13-06-2020, 13:04   #12
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Re: Starting Tohatsu M9.8 2 stroke (sat for 2 years)

So got to look at the engine today and this is the situation; Prop spins (probably irrelevant) The pull cord was part way out probably 6-8 inches hanging down, with all my force cannot pull the cord (pretty sure it was in neutral). Suggests to me that the pistons are seized but I'm guessing as I have no experience of engines. Any ideas guys, is it time to get an expert or are there some obvious things to try first ?
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Old 13-06-2020, 14:09   #13
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Re: Starting Tohatsu M9.8 2 stroke (sat for 2 years)

I picked up a frozen tohatsu from a trash bin, pulled the cowling and plug, fogged the cylinder. Put a box wrench on the crank nut and wiggled it back and forth, luckily got the thing to rotate. Put a drill motor on the nut and spun it till it was good and free. Luckily it was just stuck rings. If it had been rusted bottom end needle bearings, it would have gone back to the dumpster.
Anyway, try the wrench trick, you might be lucky, you might not.
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Old 13-06-2020, 14:20   #14
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Re: Starting Tohatsu M9.8 2 stroke (sat for 2 years)

Could be that the flywheel and magneto assembly are fused with rust. Supposed to use a special tool to get the flywheel off but there is a nifty trick that works if you decide to take it off.
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Old 13-06-2020, 15:59   #15
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Re: Starting Tohatsu M9.8 2 stroke (sat for 2 years)

Try turning the propeller by hand in gear, fog cylinders first.
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