Tohatsu 9.8 service

[lightning]

I've had my Tohatsu 9.2 two stroke engine since 2012.

Although the engine has only been used from time to time and probably 100 hours in total, l've never replaced the impeller.

l've changed the oil in the lower leg a couple of times, although not for a few years.
l've also used my grease gun on the various grease points from time to time.

l've decided that it needs a full service before it's used again.

What should l replace on this engine
l guess impeller and gaskets, spark plugs and gearbox oil. ls there anything else?

The engine starts first or second pull even when not used since the previous year. l've always flushed it if used in salt water and run it dry of fuel before storage.

lt's never been left in the water.

[Fenlander]

You've covered the main items. Also check/replace fuel filter, remove the prop and grease the splines, grease the tilt mechanism pivots and sliding contact areas.

The only other area I'd be looking at after that time period would be getting carb gaskets and seeing what gunk is in the fuel bowl and giving it a spray through the jets with carb cleaner as quite a few folks have reported issues with idle/low speed running on this motor due to gummed jets.

Having said that if it runs well I'd not argue the case if you'd rather leave the carb well alone.

[Fenlander]

I was chatting off forum and as I'd recently sorted all my kit for its winter rest before spring awakening, which will include servicing my Tohatsu 9.8 2-stroke, this seemed a reasonable thread to put more servicing info.

The complete schedule for this motor is...

Check and gap or replace spark plugs (BPR7HS-10 1.0mm gap)
Check advance/retard operation for free movement or excess play.
Check fuel filter and replace if required.
Drain carb float bowl & inspect for debris.
Check tank, pickup filter, fuel lines & primer
Set idle mixture about 1/4 turn out from midpoint, set speed to 950rpm in neutral
Check start in gear protection and engine stop switch.
Check level or drain and change gear oil (320ml of GL5)
Check and/or change pump impeller
Check external anode, remove and clean or replace.
Remove prop and grease splines
Grease all nipples and oil linkages checking tilt operates freely
Check pull cord condition

Additional work if needed.

Strip & clean carb
Remove and clean/test thermostat (requires head removal and new gasket)

[Fenlander]

Different places sell different combinations of items they call a service kit. In the first image below is what I have for the spring service. Two items could be said to be missing. The fuel filter is in my onboard spares box already and I don't think you need a kit with the gearbox anode unless you can see it's in poor condition. I usually add a carb bowl seal/gasket which is rarely in the kit even if just to keep to hand. Also personally I like to see new gearbox drain/filler seals as they do an important job keeping salt water out of the gearbox.

I bought the impeller kit in image 2 as a separate item. This comes with more items than just an impeller and single gasket you mostly get chucked in with a service kit. You may not need them all. Included is the impeller drive pin, two spring pins for the gear change rod and a prop split pin plus one more gasket that isn't always needed.

[Fenlander]

While I'm thinking about this motor I came across this Youtube the other day that explained the differences between the near identical 6,8 & 9.8 2-strokes. I am always wary of folks who say "all you need is a carb" or similar. This guy shows, certainly on the two examples he looked at, the differences include other items.

https://www.youtube.com/watch?v=jca_MhI8Pmg

[Steve509926]

Thanks for listing the above Fenlander. I'll be servicing my "new to me" 9.8 Tohatsu this winter and it gives me a good idea of what I need to order.
As I don't know the history of the OB I will probably go OTT and service/replace everything for this first service then only do what's necessary for the follow up services.
If I feel comfortable doing the first service I may post a video on the forum, if it goes t-ts up I'll keep quiet

[Fenlander]

>>>As I don't know the history of the OB I will probably go OTT and service/replace everything for this first service then only do what's necessary for the follow up services.

Yes that's what I do... with outboards and new to us cars alike. Then if you want you can stretch the next change duration of certain items according to use but at least you know at the start point everything is spot on.

[69cmw]

Originally Posted by Fenlander

I was chatting off forum and as I'd recently sorted all my kit for its winter rest before spring awakening, which will include servicing my Tohatsu 9.8 2-stroke, this seemed a reasonable thread to put more servicing info.

The complete schedule for this motor is...

Check and gap or replace spark plugs (BPR7HS-10 1.0mm gap)
Check advance/retard operation for free movement or excess play.
Check fuel filter and replace if required.
Drain carb float bowl & inspect for debris.
Check tank, pickup filter, fuel lines & primer
Set idle mixture about 1/4 turn out from midpoint, set speed to 950rpm in neutral
Check start in gear protection and engine stop switch.
Check level or drain and change gear oil (320ml of GL5)
Check and/or change pump impeller
Check external anode, remove and clean or replace.
Remove prop and grease splines
Grease all nipples and oil linkages checking tilt operates freely
Check pull cord condition

Additional work if needed.

Strip & clean carb
Remove and clean/test thermostat (requires head removal and new gasket)

How many hours has that engine been used since its last service?
Is that a standard yearly service?

[Steve509926]

Originally Posted by 69cmw

How many hours has that engine been used since its last service?
Is that a standard yearly service?

I'm sure that most would use some common sense to the above that Fenlander has listed.

If an OB has been serviced but not used for 12 months, then very little would be done.
If the OB had been run 10 - 20 hrs then maybe a few things would be checked ie: plugs - clean, reset gaps.
20-50 hrs use would entail a bit more, then so on and so forth up to 100 hours when, personally I would do a full service as Fenlander has listed.

[Fenlander]

That whole list (with the exception of removing the head to check the stat) is actually every 6mths or 100hrs as stated in the manual. Once I've got to know a new to me motor and gone through everything I flex that schedule to my own use and experience of motors.

In the case of my specific motor it's only added about 17hrs since its last attention but by the time it has the 2025 season start service I'm talking about will have gone over two winters storage periods.

My Yamaha 15 2-stroke has a very similar list but it's given as 1yr or 100hrs. They add in a thermostat inspection at that period, but that's easier to get to on the Yamaha of course. Also at 1000hrs they advise removing the exhaust guide plate and replacing if required. Those sort of hours may be reached by someone like Donny but I will never get to a fraction of that.

[Fenlander]

Worth giving Steve's video guide a look...

https://www.rib.net/forum/f36/tohats...tml#post880653