Outboard upgrade.

[munster1967]

Hi folks.
I'm currently upgrading my dt2 to a bigger motor. My choice is a used 3.5 HP mercury 4 stroke v a 3.5 HP tohatsu 2 stroke, the 2 stroke is old. Which would be better option. Only 100 pounds in difference on price. Obviously the 2 stroke is lighter , will they have similar performance.? Does the 4 stroke need to be stored in an upright position. ? (Cosmetically obviously no comparison.) !!

 

[snowbird30ds]

How old is the older one? Outboard power used to measured at the crankshaft no prop so gearbox will make a difference in actual power, not sure how long ago that changed.

 

[munster1967]

How old is the older one? Outboard power used to measured at the crankshaft no prop so gearbox will make a difference in actual power, not sure how long ago that changed.

Id say looking at it 30 years old.

 

[john_morris_uk]

Go to Alderney and buy a new two-stroke? Or keep looking for a decent second hand one at a better price?

 

[munster1967]

Go to Alderney and buy a new two-stroke? Or keep looking for a decent second hand one at a better price?

So. In your opinion the 2 stroke is better. ?

 

[VicS]

How old is the older one? Outboard power used to measured at the crankshaft no prop so gearbox will make a difference in actual power, not sure how long ago that changed.

1983
ICOMIA 28/83 test procedure.
Some manufacturers may have quoted propshaft power earlier.

 

[john_morris_uk]

So. In your opinion the 2 stroke is better. ?

100% for me. Lighter & quieter.

We have had several two strokes of various HP ratings up to 9.8 and they have all purred compared to our daughter’s 6HP Tohatsu 4-stroke outboard. Perhaps hers is an exception, but the weight difference is not a joke.

 

[Lightwave395]

Having moved to a swinging mooring earlier this year I thought a tender refresh would be useful so I bought a larger 2.9M heavier inflatable with inflatable keel and floorboards. It's a bit heavy and wouldn't be very good for carrying onboard and constant re-inflating but works well to get out to the boat with supplies and other gear.
To go with this I sold my reliable Mercury 3.3hp 2-stroke and bought a new Mariner 2.5hp 4 stroke outboard to get reliability and 5 years warranty.

Not the best decision I've made, the Mariner does indeed start on first pull and is quiet but it weighs a ton and doesn't seem to have the power of the old engine. I've modified an old golf trolley to make life easier wheeling the engine down to the dinghy

I am watching out for the most recent and lightly used 2 stroke I can find, I have read that the new engine could be upgraded to a bit more power but haven't as yet discovered how that could be done

 

[B27]

Hi folks.
I'm currently upgrading my dt2 to a bigger motor. My choice is a used 3.5 HP mercury 4 stroke v a 3.5 HP tohatsu 2 stroke, the 2 stroke is old. Which would be better option. Only 100 pounds in difference on price. Obviously the 2 stroke is lighter , will they have similar performance.

The useful power you get out of either of them will depend on how well the prop matches the boat.
Either motor can have problems.
If you need to frequently lift the motor off the boat, then the 2 stroke is a plus, due to the weight and less issues with lying it down carefully to avoid the sump oil escaping. The fourstroke might be quieter and use less fuel.
The two stroke might have a better spread of torque so less sensitive to the correct propeller.

You may find that neither is exactly a game changer compared to the existing 2HP.

I would probably choose on condition.

Some of those small 4 strokes have a problem with the neck of the fuel tank being exposed to sunlight and failing if kept outdoors too much, a new tank is expensive.

 

[Boathook]

Having moved to a swinging mooring earlier this year I thought a tender refresh would be useful so I bought a larger 2.9M heavier inflatable with inflatable keel and floorboards. It's a bit heavy and wouldn't be very good for carrying onboard and constant re-inflating but works well to get out to the boat with supplies and other gear.
To go with this I sold my reliable Mercury 3.3hp 2-stroke and bought a new Mariner 2.5hp 4 stroke outboard to get reliability and 5 years warranty.

Not the best decision I've made, the Mariner does indeed start on first pull and is quiet but it weighs a ton and doesn't seem to have the power of the old engine. I've modified an old golf trolley to make life easier wheeling the engine down to the dinghy

I am watching out for the most recent and lightly used 2 stroke I can find, I have read that the new engine could be upgraded to a bit more power but haven't as yet discovered how that could be done

Someone mentioned that quite a few small engines have different size carbs to increase the power. If the power is increased it may mean a new coarser pitch prop as well. The person also mentioned google being good.
The person isn't myself either but I might look into it for my malta 2 stroke !

 

[James_Calvert]

Some years ago I concluded a 4hp Evinrude would be the best and lightest available upgrade to a Mariner 2hp.

Both 2 stroke, the Evinrude has 2 cylinders v the Mariner's 1.

I wasn't wrong, the Evinrude would get our inflatable planing.

Spares not so easy to come by now though...

 

[munster1967]

Some years ago I concluded a 4hp Evinrude would be the best and lightest available upgrade to a Mariner 2hp.

Both 2 stroke, the Evinrude has 2 cylinders v the Mariner's 1.

I wasn't wrong, the Evinrude would get our inflatable planing.

Spares not so easy to come by now though...

Thank you. Sounds like a plan.

 

[Graham376]

100% for me. Lighter & quieter.

We have had several two strokes of various HP ratings up to 9.8 and they have all purred compared to our daughter’s 6HP Tohatsu 4-stroke outboard. Perhaps hers is an exception, but the weight difference is not a joke.

Two stroke for me as well, less to go wrong and easier to fix if it does. I've found parts for old Tohatsu engines readily available.

 

[jwilson]

Not long ago used a 3.5 Tohatsu two-stroke and a 2.5 Yamaha 4-stroke on the same 3.1 metre airdeck and keel inflatable, both times one-up The 2.5 would never quite get it on the plane, though it would shove it along well dragging a fair quarterwave. It planed pretty cleanly and considerably faster with the 3.5. The two-sroke so much lighter, and since I have started feeding it Aspen 2 instead of ordinary petrol plus oil the occasional carb-gumming and need for dismantling and cleaning seems to have stopped. Both these outboards are only used very intermittently. I always shut off fuel to stop them.

 

[greeny]

2 stroke every time for me. Less problems with E5/E10 fuel. Less moving parts so less to go wrong. Very simple engines. Lighter for equivalent HP. No brainer in my opinion.

 

[munster1967]

Ok update. i bit the bullet and bought a mariner 2.5 HP 4 stroke. Beautiful motor compared to the old dt2. 2 HP. A lot smoother, a lot easier to start, more powerful by a good 20 percent and the neutral gear is great to have. ! Would recommend to anyone.

 

[Fimacca]

I think tohatsu make those mariners - if so there is a upgrade carb kit to make it more hp - so you can plane away !!

 

[munster1967]

Yes tohatsu. Great motor. . The 2.5 actually got me on the plane briefly! Reaching 16.5 kmph but only briefly. Which I was surprised with. It's a powerful little unit.

 

[munster1967]

2 stroke every time for me. Less problems with E5/E10 fuel. Less moving parts so less to go wrong. Very simple engines. Lighter for equivalent HP. No brainer in my opinion.

The 2 stroke in my experience was Harder to start, noisier, and no where near as smooth . No comparison in my opinion.

 

[Fimacca]

I went torqueedo - dreamy , no noise.......someone giving up sailing had a little used one so I snatched it......
2 stroke suzuki to
4 stroke tohat
to torqee......