PabloPicasso
Well-Known Member
The carb on my 3.5hpbtohatsu 2 stroke has a drain plug screw.
Just empty the few drops of fuel before packing away at the end of your trip. Just don't lose the screw on a pebbly beach.
Looking to purchase a 2.3-3.5 hp outboard
- Thread starter Denngeor
- Start date
Just empty the few drops of fuel before packing away at the end of your trip. Just don't lose the screw on a pebbly beach.
Mark-1
Well-Known Member
This. It's the least outboard you can get away with. I suspect down under still legal to buy new as a private individual, as well.
I love the air cooled Hondas but they're a little heavier.
Mark-1
Well-Known Member
I use the same 2T oil as my chainsaw which I'm sure is biodegradable. Depending on where you draw your boundaries E-Engines are also awful for the environment, as is boating in general. As is life in general.
E-Engines are better in every way except price and speedy energy replenishment. So if you don't need either of the last two then great. If you do then you do. I don't think any of that is news to anybody.
lustyd
Well-Known Member
The carb on my Yamaha has a drain plug screw too. It doesn't lead anywhere, solid metal underneath it despite there being a rubber hose attached the other side of the metal.
4 strokes are better not drained with modern fuels, discussed here recently and someone referenced research on the topic
PabloPicasso
Well-Known Member
Interesting, I must've missed that.
Does modern fuel not leave a gum like deposit behind once its evaporated?
Does modern fuel not leave a gum like deposit behind once its evaporated?
lustyd
Well-Known Member
It contains ethanol which attracts water which in turn corrodes the internal surface of the carb if you add air by draining and that aluminium oxide dust blocks the jets.
Gumming was mostly an issue with two strokes where oil leaves a residue.
Last edited:
Refueler
Well-Known Member
Gums is actually a factor of its own and not due to 2T oil. It is part of the Oxidation Stability factor.
Gums form out of the gasoline itself due to heat, light and oxygen. It can be seen as small dark brown 'blobs' that drop to bottom of open jar of Gasoline when stored in warm .. well lit location such as a windowsill.
My company for years were involved in injecting Anti-Ox / Gums reduction additive to Gasoline ... as well as various other additives.
2T oil dropping out of the Petroil mix is when the gasoline basically vapourises off and leaves the heavier fraction behind. 2T oil is blended to actually be stable in Petroil mix.
Gums form out of the gasoline itself due to heat, light and oxygen. It can be seen as small dark brown 'blobs' that drop to bottom of open jar of Gasoline when stored in warm .. well lit location such as a windowsill.
My company for years were involved in injecting Anti-Ox / Gums reduction additive to Gasoline ... as well as various other additives.
2T oil dropping out of the Petroil mix is when the gasoline basically vapourises off and leaves the heavier fraction behind. 2T oil is blended to actually be stable in Petroil mix.
NormanS
Well-Known Member
I used to have a small two stroke, but the waterways kept on getting blocked with salt deposits. I now have the air cooled Honda. Yes, it's noisy, but no cooling water problems. I use a Briggs and Stratton fuel conditioner which claims to keep petrol in good condition for years.
Refueler
Well-Known Member
Most 'conditioners' are based on Anti-Oxidant additive ..... they just do same job as the 1000's of tons my company injected over many years - but yours will be at a price astronomically higher than ours !!
NormanS
Well-Known Member
As I use about 5 litres of petrol in year, and wee bottle of fuel stabiliser lasts for several years, the price is immaterial.Most 'conditioners' are based on Anti-Oxidant additive ..... they just do same job as the 1000's of tons my company injected over many years - but yours will be at a price astronomically higher than ours !!
Refueler
Well-Known Member
PabloPicasso
Well-Known Member
Oh that's just great that is. Don't drain the carb and I'm left with gum and 2t oil blocking the jets.
Do drain it and the caustic content of modern fuel.oxidises the internal metals, blocking the carb
Damnned if you do & damned if you don't.
What kind of sick world have we created?
NormanS
Well-Known Member
Oars are good.Oh that's just great that is. Don't drain the carb and I'm left with gum and 2t oil blocking the jets.
Do drain it and the caustic content of modern fuel.oxidises the internal metals, blocking the carb
Damnned if you do & damned if you don't.
What kind of sick world have we created?
lustyd
Well-Known Member
No no no!! Sorry if I was unclear. on a two stroke you should drain it. The oil will coat the carb and stop corrosion and draining stops the oil being left after petrol evaporates.
4 stroke doesn’t have oil to protect the metal so if you drain it the water that’s in the ethanol and the air you put in causes corrosion. Use E5 though to minimise ethanol
thinwater
Well-Known Member
I had a Merc 3.5 2 stroke on my tender for many years. Very light. Nothing bad to say about it. I did add an in-line mower-type gas filter, since the strainer in the tank was inadequate. After that, no problems.
PabloPicasso
Well-Known Member
Well thank you for that, lustyd, I will sleep well knowing the modern world we created isn't entirely wicked after all.
snowbird30ds
Well-Known Member
If leaving it longer term give it a last carb bowl full of Aspen fuel and it will start and run fine next season.
PabloPicasso
Well-Known Member
How much do you pay for aspen?
A quick look online sees a huge variation in price.
A quick look online sees a huge variation in price.
PetiteFleur
Well-Known Member
I used a 2.3 Honda until January 2025, excellent engine, I always use Premium E5 petrol + Honda additive, don't drain the carb and even though never used in 2025 it started 1st pull in October just to test it. Not used as I was bought an ePropulsion elite for combined Xmas & birthday present from my family. It's superb, quiet, always works, forward & reverse & anyone can use it, very light, no problem for my wife or grandchildren. But I do only use it to go from shore to mooring. It will run for over an hour on half throttle. Very pleased with it.
Mark-1
Well-Known Member
Where can I source these self-restrained children capable of an hour at half throttle? The kids inflicted on me are the living answer to the question: "What would Bo and Luke Duke look like with 3.5hp at their finger tips".
On Saturday my son and I took the dinghy to our nearest YC for a Hot choc with our Tohatsu 3.5hp 2T. 1NM distance. I'd taken a half a litre which I thought would be plenty, as an afterthought I took a spare litre, just in case. My son burned through the lot. Flat out the whole way. Donuts. Figure of 8s. 34m45s going, 49m58s coming back.
