Tohatsu 9.8 2S newbie

Steve509926 · 04 July 2024, 12:37

I've just bought a 9.8 2s Tohatsu and as I've never owned anything 2s (apart from lawnmowers and chainsaws) I will probably be asking a few dumb questions over the coming weeks.

It has been dry stored for 12 months and prior to that has done very few hours, for 2 years (19-21) it was tucked away in a locker on a sailboat.

After checking what I could, I turned it over and it started 2 lazy pull with minimal choke.

https://www.youtube.com/shorts/IQjmr62tU0Q

I brought it home a decided to flush and clean it before I service it.

Whilst flushing I've noticed an oily scum/tide mark around the top of the builders bucket. Is this normal for a 2s? or is it running a bit rich? Mixture is 50:1

To my ear the idle speed sounds a bit fast? but I don't really know what it should sound like.

Thanks in advance.

chipko · 04 July 2024, 13:32

Nice one Steve, that looks very smart and sounds fine.

Oily scum on bucket rim normal after running/flushing.

Idle speed should be around 750 in gear and 950 in neutral.

Enjoy your new motor.

Steve509926 · 04 July 2024, 13:53

Thanks chipko, it was a bit of an impulsive purchase after Mr F highlighted it was for sale.
The 20hp is overkill on Windermere with the 10 knt restriction and on the last trip I had to Pembrokeshire, I found loads of places to launch if I had a lighter setup. So if I like it I may pair it up with a lighter sib for solo use, keeping the SD360 and the 20hp efi for family use.

Fenlander · 04 July 2024, 14:05

Yep nice one indeed... a minter.

50:1 is correct for these, just use a top quality marine spec 2T oil, measure carefully and accept you will see a bit of a rim around a yellow bucket. Upgrade to a black bucket would cure it.

Yes the idle does sound a bit fast but no doubt you'll get a mini tach for it and know for sure.

Will you give it a run out on your SIB soon?

There's really nothing to servicing them as they are so basic but I would at least draw a gear oil sample to check there's no water in it and consider doing the impeller. I have the full set of genuine Tohatsu parts on the bench to do mine, together with a gear oil change.

Also worth getting a spare float bowl gasket. Ive not had trouble with either of my 9.8s but others have needed to do carb cleans while on holiday so good to have that to hand.

Parts were from Marine Tech in Norwich who I've always found good. I've gone for this Total gear oil as it meets the spec and in the 250ml tubes is half the price of Quicksilver/Yamalube.

https://www.ebay.co.uk/itm/373537080...Bk9SR5yakN2PZA

Steve509926 · 04 July 2024, 15:01

Hi David, hopefully I'll manage to get upto Ullswater one day next week to give it a run, see if it needs any transom packers and see what rpm is at wot.

Gear oil is clear and the sparkplugs are so lightly discoloured they are like new. I will give it a service just for peace of mind and it adds to my knowledge.

I've taken the prop off (it's bone dry not a hint of grease so I don't think it's ever been off) to see what is fitted. The only marking on it is F8.5, which I presume is an 8.5 pitch, but there is no indication as to what the diameter is. If I measure from the centre of the prop to the tip of a blade x 2 = 9", does that sound about right for an oe prop 8.5 x 9 ?

Fenlander · 04 July 2024, 15:19

Info here

https://www.tohatsu.com/marine/int/a...ries/prop.html

Steve509926 · 04 July 2024, 15:27

Thanks David.

Tommy c · 04 July 2024, 15:31

I bought a mint yam 5 that had been stored in a sailboat locker.
It had been used at sea.
I noticed that the tell tale was quite warm.
On investigation the thermostat and water galleries was choked up with salt.
Just a bit of a heads up

Steve509926 · 04 July 2024, 15:32

Thanks Tommy, good information to know about.

Fenlander · 04 July 2024, 18:57

Re pitch Steve you might remember for two adults, dog and kit on the Aerotec I pitched down to a 7.5" from the standard 8.5" to gain a worthwhile amount of responsiveness using the 9.8.

Brinormeg · 04 July 2024, 19:00

Quote:

Originally Posted by Steve509926

Thanks chipko, it was a bit of an impulsive purchase after Mr F highlighted it was for sale.
The 20hp is overkill on Windermere with the 10 knt restriction and on the last trip I had to Pembrokeshire, I found loads of places to launch if I had a lighter setup. So if I like it I may pair it up with a lighter sib for solo use, keeping the SD360 and the 20hp efi for family use.

Nice one Steve….hopefully you’ve got yourself a good one there.

I’m definitely starting to think down the same lines as you, as in having a lighter 2nd setup.
As I get older and my fit late teenage son is starting to find other interests (wine,women and song no doubt

)I can see myself really struggling with our setup. Plus we have friend with a really nice light setup just down the road that I could meet up with on a more regular basis, without relying on getting an unwilling crew together every time.

Steve509926 · 04 July 2024, 19:28

Quote:

Originally Posted by Brinormeg

Nice one Steve….hopefully you’ve got yourself a good one there.

I’m definitely starting to think down the same lines as you, as in having a lighter 2nd setup.
As I get older and my fit late teenage son is starting to find other interests (wine,women and song no doubt

)I can see myself really struggling with our setup. Plus we have friend with a really nice light setup just down the road that I could meet up with on a more regular basis, without relying on getting an unwilling crew together every time.

Thanks Brin I think I've got a good un! and I can't believe how light it is.

I can still easily manage the SD360 & 20 efi using transom wheels on my own providing it's on a slip, hard sand or if the waters edge isn't too far away.
What is swaying me towards a second set up was the number of locations in Pembrokeshire that I couldn't take advantage of because it was too steep, too rocky or in the case of Tenby/Saundersfoot the sea was bloody miles out! The pictures in #11 & #16 don't really show how steep it is, but believe me there is no way you could launch using transom wheels. But I could have done so with a lighter blow & go setup.

https://www.rib.net/forum/f50/return...dau-90991.html

smallribber · 05 July 2024, 07:00

Those are very good indeed I have 2 of them. The next best is the Yamaha 15 hp 2 stroke for way more power but still comparatively light. Or simply buy the yam 9.9 and put in new reed valves to make it 15 if this has not already been done

Steve509926 · 07 July 2024, 21:22

The weather tomorrow is looking reasonable for the first outing of my new to me 9.8 Tohatsu.
I'm aware that each members setup will be different (different transom height, different weight) but do you have your 9.8 Tohatsu sat on the transom or raised?

Fenlander · 07 July 2024, 21:26

Do you know it’s only the Aerotec where transom height has been an issue for me. On multiple other sibs I’ve just hung the outboard on and away.

smallribber · 07 July 2024, 21:26

Quote:

Originally Posted by Steve509926

The weather tomorrow is looking reasonable for the first outing of my new to me 9.8 Tohatsu.
I'm aware that each members setup will be different (different transom height, different weight) but do you have your 9.8 Tohatsu sat on the transom or raised?

Sitting on the Transom assuming yours is a Short/Standard Shaft

Steve509926 · 08 July 2024, 21:16

Had a really good day at Ullswater testing the 9.8hp 2s with the 8.5p prop that it came with.
I also tested it with the Dole fins fitted to the OB, to see how effective they are, or not!

8.5p trimmed out on the 2nd hole:-

0mm packing, 13.0 knots at 4980, loads of splashing coming over the transom, no loss of grip in tight turns

6mm packing, 13.2 knots at 4990, still a fair amount of splashing, no loss of grip in tight turns

12mm packing, 13.6 knots at 5010, hardly any splashing, very slight loss of grip in tight turns

18mm packing 13.2 knots at 5010, no splashing, big loss of grip in tight turns

With Dole Fins:-

0mm packing, 12 knots at 4800, lots of splashing, wouldn't stay on the plane

6mm packing, 12.4 knots at 4850, still a fair amount of splashing, would just stay on the plane

12mm packing, 12.6 knots at 4950, got on the plane ok (but no different to not having fins) no splashing, no loss of grip

18mm packing 12.6 knots at 4950, got on the plane ok (but no different to not having fins), no splashing, no loss of grip

IMO 10mm packing on the transom with a 7.5p prop should be the best combination for my set up - obviously without Dole fins as they didn't have any benefit what so ever.

I will hopefully get out again next week with a 7.5p prop which I think will be far better suited to my set up.

The OB performed very well its also quieter than I was expecting.

willk · 08 July 2024, 21:41

Interesting set of results Steve - lot of work recording all that!

It sounds like a similar experience to mine back in the day (I bought a 9.8 with a 8.5 pitch and fins). I didn't use them. It might have benefitted from a 7.5 pitch.

Steve509926 · 08 July 2024, 21:45

Quote:

Originally Posted by willk

Interesting set of results Steve - lot of work recording all that!

Bit OCD when you think about it willk, but I did use the camera on my phone to record it.

Fenlander · 09 July 2024, 00:54

Useful data to have on the forum Steve. I've just looked back and with the down pitch to a 7.5" I managed 14kts at 5450rpm. That was 2-up. It's not just about the speed, the motor just felt better throughout the range.

I was interested you suffered splash and needed packers though... do you get that at all with your Mercury and is that direct onto the transom?