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post #191 of 257 Old 03-29-2012 Thread Starter
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Re: Nissan / Tohatsu 6h 4 stroke

It works ok on my boat but my old 20 inch johnson 4hp 2 stroke produced about 20% more thrust on the top end (as measured in thrust tests and on boat performance) I lost almost an entire knot of speed when I went to the new 6hp engine. Using the 5.99 pitch prop brought it up some but I was still about .5 knots under what my old 4hp engine could push the boat at. It was a big disapointment to me. I spent the extra money on the 6hp engine to give me that extra edge in perfomance on bad and choppy days. Instead it ended up being worse other than that the new 25 inch shaft no longer came out of the water in chop or wakes.
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post #192 of 257 Old 03-30-2012
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Re: Nissan / Tohatsu 6h 4 stroke

Just picked up my 2012 motor today. Is MFS4C(L) 2012 Tohatsu 4hp 20" shaft. Have upgraded to 6hp with carb upgrade, added alternator and replaced prop with 7.375 in dia 6pitch hi thrust prop. This is identical to the motor and prop purchased last year (and stolen in October) except 2 model years newer

Boat came with Johnson 2 stroke 4hp 15 in shaft. Replaced with Johnson 4.5hp 20 in shaft. both were from 1980s. Neither had hi thrust prop. Neither provided nearly the power of the new Tohatsu. With the 4.5 I could motor at 5.7 knots over water on a good day but adverse current or wind would quickly drop it down to 4.5 knots or against 25+ knots wind to between 1 and 3 knots.

The new motor last year consistently provided higher speeds (as high as 6.8 knots over water) and against current or wind was far less affected.

The 4.5 hp Johnson Seahorse was low on compression tests as well but semed to run well regardless

Purpose of this post is to state that the propeller we use called the "Hi Thrust" propeller (and I believe same one on the Sailpro) is pitch 6 and diameter 8.375" according to the paperwork that came with my engine.

I have been extremely pleased with this engine

Mike

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post #193 of 257 Old 03-30-2012
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Re: Nissan / Tohatsu 6h 4 stroke

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Originally Posted by mikehoyt View Post
Just picked up my 2012 motor today. Is MFS4C(L) 2012 Tohatsu 4hp 20" shaft. Have upgraded to 6hp with carb upgrade, added alternator and replaced prop with 7.375 in dia 6pitch hi thrust prop. This is identical to the motor and prop purchased last year (and stolen in October) except 2 model years newer

Boat came with Johnson 2 stroke 4hp 15 in shaft. Replaced with Johnson 4.5hp 20 in shaft. both were from 1980s. Neither had hi thrust prop. Neither provided nearly the power of the new Tohatsu. With the 4.5 I could motor at 5.7 knots over water on a good day but adverse current or wind would quickly drop it down to 4.5 knots or against 25+ knots wind to between 1 and 3 knots.

The new motor last year consistently provided higher speeds (as high as 6.8 knots over water) and against current or wind was far less affected.

The 4.5 hp Johnson Seahorse was low on compression tests as well but semed to run well regardless

Purpose of this post is to state that the propeller we use called the "Hi Thrust" propeller (and I believe same one on the Sailpro) is pitch 6 and diameter 8.375" according to the paperwork that came with my engine.

I have been extremely pleased with this engine

Mike
If your new engine really is less affected by the current than the old one, this means it has an ability to warp the fabric of space. Quite a feat in a $900 consumer device. I am envisioning future spacecraft powered by banks of Tohatsu outboards.
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post #194 of 257 Old 03-30-2012
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Re: Nissan / Tohatsu 6h 4 stroke

My boat can also warp the fabric of space as you fail to realize how MUCH OUTBOARD PROPELLER technology has changed form the 80s all we got is a one two blade prop made for a plaining hull and tough luck if its NOT the right one for a displacement hull





While i mostly WAG at this stuff i did spend a few thousands hours in outboard/stern-drive school



Altercation which i bought it brand new when i was 26 years old J24 with nice 6HP twin Evinrude with POS two blade prop



Tangent my most recent J24 with the Tohatsu/Mercury outboard motor and the stupid expensive 105 dollar propeller

I do not believe a more valid comparison exists and other than the single cylinder vibration the motor is fabulous and pushes the boat BETTER due to the better propeller design

Clearly if Mr Discontented owners motor will only reach the mid 4000 RPM range there is something wrong as they will reach that RPM tided to a dock



And of course there is Seafever at well over 8000# which moved at 4.5 knots at 3/4 + throttle as it was a 16 mile move and i did want to use it again on the J24

And i am sorry you hate one of the biggest selling motors of all time sold as Tohatsu/Mercury/Nissan/and Now Evinrude so i guess they have somehow fooled two other huge company's into selling the poor motor also
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post #195 of 257 Old 04-02-2012
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Re: Nissan / Tohatsu 6h 4 stroke

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If your new engine really is less affected by the current than the old one, this means it has an ability to warp the fabric of space. Quite a feat in a $900 consumer device. I am envisioning future spacecraft powered by banks of Tohatsu outboards.
Now that is very humourous! I do in fact have Tohatsus on my Spaceship but I upgraded to a 9.8 hp model for it.

Seriously though I was more affected by wind and waves. The adverse current just made my already underpowered and too slow 4.5 hp all that more frustrating. The 6hp with hi thrust prop moves the boat over a full knot faster in ideal conditions than the 4.5 did so my comment was more that having an extra knot of speed to begin with was nice when travelling against a current. Certainly a lot better against a wind or waves though as the boat does not seem to slow down as much with each wave and takes less time to get back to speed.

I do wish it was only $900. After adding the alternator, prop and upgrading to 6hp was over $2100.

Mike

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post #196 of 257 Old 04-02-2012
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Re: Nissan / Tohatsu 6h 4 stroke

Took the new Tohatsu 6HP 4stroke, 25inch shaft, for it's first spin yesterday. Vibrates a bit hanging off my Dovekie side mount, but otherwise it was a pleasure. A bit more power than I need to reach hull speed, but I wanted the extra power for upstream river running and for pushing into a head wind, because the Dovekie has a lot of free board and little wetted surface (4 inch draft with leeboards, rudder and centerboard up). Over 6 knots at a bit less than half throttle. Almost three hours out and my three gallon tank still looks full through the fill cap and on the gauge. Was easy to pull start. Shifted a bit hard. May not be everybody's cup of tea, but at 1500 bucks, with alternator, delivered to my door, it suits my needs. If reliability is high, and she sips fuels as she appears to do, I think I will be a happy camper.
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post #197 of 257 Old 05-24-2012
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Re: Nissan / Tohatsu 6h 4 stroke

Hi TohatsuGuri & audeojude,
I have a Tohatsu MSF 6B Sail Pro that is fitted to my 22 ft Sailing trimaram weighing around 1600lbs loaded.
Generally I am very happy with the motor, apart from the vibrations, but I knew that would be an issue with the single banger.
The standard prop that came with the motor ( according to the owners manual) is a 7.8" dia by 7". The only makings that I can find on the 3 bladed prop is 9A cast into the rear of one of the blades, but its hard to be sure as its not well defined.
In flat water with no wind I get 5.5 knots at half throttle & about 7k at WOT.
My local Tohatsu dealer (in Australia), is recommending that I get the 4 bladed high thrust prop, but after this thread I am far from convinced this is the right way to go. He is saying that I could incure gearbox damage with the standard prop by having the motor over rev. I am about to get a digital tacho & see what the revs are at WOT.
I would be interested on getting your opinions on going to a higher pitch for my boat as this seems contrary to the theme of the thread.
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post #198 of 257 Old 05-24-2012
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Re: Nissan / Tohatsu 6h 4 stroke

Incorrect. the Sail-Pro comes standard with the special 399B645121 "elephant ear" 3-blade prop, which is 6-pitch. There is no Tohatsu 4-blade prop for the 4/5/6. Those are only available to fit the 8/9.8. Solas has one for the 15/20.

Paul Van Voorhees
Certified Tohatsu TLDI Technician
Mgr, Obersheimer Sails
Buffalo, NY USA
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post #199 of 257 Old 05-24-2012
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Re: Nissan / Tohatsu 6h 4 stroke

I just purchased a new Tohatsu 6HP. The owner's manual states that there is a built-in rev limiter. I am changing to a 7.9"diameter X 6.0 pitch prop for slower trolling speeds. We are at 6,000' elevation so it will be interesting to see if it will hit the rev-limiter? Am totally satisfied with the engine, it gets a wide 12' Jon boat with 2 people and all our fishing gear up on a plane and runs at 10.2 MPH at 6,000' elevation.

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post #200 of 257 Old 05-24-2012 Thread Starter
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Re: Nissan / Tohatsu 6h 4 stroke

I have to say that I am unaware of a 4 blade prop for this motor. To my knowledge there is a 6,7,8, and 9 pitch props and then a special high thrust prop that is sold as 5.99 pitch. As to which one is stock on the super longshaft version of the motor for sailboats, when mine was shipped it came with the stock 8 pitch prop. I have tried the 6 pitch and the 5.99 high thrust elephant ear prop on it also. If your going to use this with a sailboat I would get the 5.99 pitch high thrust prop. It is a 3 bladed prop. It has massive thrust from a stop and allows the motor to turn the most rpm's of any of the props I tested. It still wont meet factory spec rpms but it is better than any of the other props I tested.

As to over reving this engine. It as mentioned by someone else has a rev limiter in it, if you rev it up in neutral you should hear it kick in. however it would suck if it didn't work. However even if it didn't I wouldn't worry about it. There is not a prop sold by tohatsu that will at wide open throttle even get past 5000 rpm. Tohatsu gives a 6000 rpm top end in the specs but the only way one of these engines coudl turn that fast is in neutral. With a 6 pitch prop and the 5.99 high thrust prop this thing will at most turn between 4800 and 5100 rpm even on a dingy.

If you have a newer engine and it's gettign better than this then tohatsu has changed something on it. I have physically tested a couple of them and they gave identical performance results.
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