2-Stroke vs 4-Stroke Outboards

[GopherBaroque]

Originally Posted by sailingharry

Well, when I get challenged, I research.

Outboard oil is TC-W3. It supposedly is zero ash, for environmental issues. It also is designed to run at lower engine temperatures.

Chain saw/leaf blower oil (not bar oil) is TC. No "W." This is "low ash" and is also formulated for higher temps.

Now I have no idea what to believe!

-got me curious, too, and found "Ashless" TCW3 vs. "Low Ash" JASO/ISO 2 stroke oil":

The oils are blended according to a formula that has been developed for two-stroke snowmobile engines and this oil is usually given a rating from the American Petroleum Institute (API) of "TC", the Boating Industry Association (BIA) rating of "TC-W", or the National Marine Manufacturers Association (NMMA) rating of "TC-W II." All of these formulas were originally developed for outboard engines and were modified to suit the needs of snowmobile engines; however, motorcyclists that used these oils found that their air cooled engines ran the best on the oldest API TC oils. These API TC formulas contained a higher level of bright stock 150, a high density petroleum base stock with a consistency similar to honey, that gave the best protection against piston seizure and bearing failure. To prevent carbon buildup in the piston ring grooves, these TC oils used metal based detergents that were very effective in motorcycle engines but caused some problems in outboard engines when operated at long periods of time at one throttle setting. A whisker-like bridge could form across the sparkplug gap to permanently foul a cylinder under these conditions while the motorcyclist operating his engine at a constantly changing throttle setting never encountered this problem. When the BIA developed the TC-W rating, they excluded the use of these metal-based detergents in favor of organic detergents to eliminate this problem in outboard engines. These TC-W oils (two-cycle, water cooled) also contained lighter base oils without the bright stock 150. For engines operating in the 4,000 rpm to 5,000 rpm range, the absence of the bright stock 150 had no affect on piston and bearing life. However, off-road motorcyclists testing these new TC-W oils were disappointed with the bearing life of their engines operating at 10,000 - 11,000 rpm and quickly returned to using the TC oils.


The original discussion goes into a lot more detail...my conclusion is that TC-3 oil in my Johnson 4hp Deluxe should be fine to get back to civilization. But make a note to move the throttle periodically.

[hukilaumike]

My old 23 foot sailboat used an outboard as the aux power. I used a two stroke for over 15 years on that boat; the first engine was original to the boat and didn't last too long for me. It just became increasingly unreliable. When I repowered, I thought about going to one of the new four strokes, but that would have required getting a new engine bracket and redoing the motor mount on the transom. So I bought a new two stroke (Nissan; this was back when they were still available freely here in the US). That engine was reliable for a number of years. Then it wasn't. The starter button failed (given the position of the engine over the transom, pull starts were more than a little awkward); then the carb float wouldn't budge; then the power head needed to be rewelded (don't ask). The final straw was when the thermostat froze and I wound up spending waaaaay more than I wanted to fix it. A short month later, it refused to start for the last time.

I was actually kind of excited to replace it with what I hoped would be a quieter, more powerful four stroke. I was ultimately disappointed. I bought a Tohatsu, and while it was much quieter at low speeds, it was just as loud as the two stroke at normal operating throttle. And I was expecting the much vaunted "higher torque" of a four stroke to make a noticeable difference, especially since I sprung for the high thrust prop. Nope.

Not only that, but after less than a month's use, it stopped peeing cooling water. I had to take it back to the dealer who said it was just a clogged discharge hose. Then it had trouble starting. Then the discharge hose got clogged again.... In short, a big disappointment. I sold that boat and engine the next spring. To be fair, the 8 hp Tohatsu four stroke wasn't that much heavier than the 8 hp Nissan two stroke (about 10 lbs.). They've really cut down on the weight of the latest four strokes. But anyone who has a reliable outboard, that's gold baby. Hold on to it.

[Miker1944]

I will leave the 2 stroke, 4 stroke, decision up to each individual. I only want to clear up a piece of misinformation. 2 strokes and the parts for same, are still available legally in the United States. The caveat is that, to legally buy a 2 stroke, you have to be a commercial entity, fisherman, dock installer, etc.

[sailingharry]

Originally Posted by hukilaumike

But anyone who has a reliable outboard, that's gold baby. Hold on to it.

The 1992 Evinrude 8 2-stroke I mentioned up-thread was kind of humorous. It was given to me, with a bunch of broken parts. It was old and tired. It kept breaking things. It had an exhaust leak in the lower unit that I couldn't find (finally did at the end of the summer) so it wouldn't run with the cowling on. The fuel hose that came with it was probably original, and it kept breaking at the motor and I'd have to cut 2" off and reattach.


But this ratty old motor started on 2-3 pulls every single time, going ashore in remote places way Down East (and into the Bay of Fundy) 2-3 times a day (we have a dog) for 110 days this summer, and I never had the slightest doubt it would run. The "problems" were just entertainment and fun to bitch about.



I even sold it for $300!



Yes, a reliable outboard is GOLD!

[wgh52]

I can’t answer your question concerning have 4 strokes improved enough but I can give you my experience. Around 2009 I purchased a Tohatsu 18 HP for my dinghy. If the engine set for a few weeks it seemed it would not start. I would end up pulling the carb and clean up the jets to get it running again. I always ran the gas out of the carb before any layups. I would always buy marine gas. After years of frustration, I sold the engine and found a Nissan 5hp in excellent condition. This past summer cruising the Chesapeake, it always started with one or two pulls. It is lighter and easy to handle. For the same HP the two stroke seems to have more power. For me cruising is enjoying the sailing and communities we visit, not working on engines.

[Sailing Hanse37]

Originally Posted by thomm225

The 4 strokes are simply better, more clean running, and longer lasting than the 2 strokes.

Plus they are much more efficient on fuel.

I've changed the plug once on my 4 stroke outboard in 10 years. Try that on a 2 stroke.

On top of all that, all you add is gas and once/year an oil change.

Sorry to disagree somewhat. We bought a brandnew 5hp 2stroke in Surinam. Our advantages: weighs a LOT less than 4 stroke equivalent, mechanically much simpler… almost no maintenance needed, no oil change needed. diy is easy on these motors and they have a reputation of being indestructible. As for the fuel consumption: ours in 1 year is about 20 litres, so fuel economy is not important. We are on our first plug after 4 years, but i’ll maybe replace it in the coming months.

[David Mathis]

Another case of EPA gone wild.

We have two outboards, both two strokes, a 1985 Evinrude 9.9 and a 1987 Yamaha 150. Both run perfectly and start easily. About every three years the gear oil is changed and every ten years they get new spark plugs and impellers. At about the 25 year mark they had their carburetors rebuilt. At this rate, they'll still be running on my 100th birthday when I plan to water ski behind the Yamaha.

The EPA did a great job addressing industrial pollution, 8-10 mpg cars, municipal sewage discharges, and unregulated landfills but now they don't know when to slow down. We spend far too much money to meet needless EPA regulations. Clean air and a clean environment are needed but there has to be a limit on the EPA power. Did you know that fuel injected chain saws are being introduced to meet new EPA regs, at about 2-3X the cost of the carbureted ones. And don't get me started on the requirement for urea on the large world cruising yachts with twin multi cylinder diesels.

It's time for congress to look at a budget reduction for the EPA.

[OneBoatman]

Being up in my yrs for my tender, I did prefer the light wt of 2 stroke but whether 2 or 4 stroke want the outboard to have a self-contained tank. I don't miss having to carry 2 Str oil. I still sometimes forget my leash but can use piece of string if need be. My davits will hold me, my tender, and a 4 H.P. Yam 4 str and I can transfer it to the rail if I anticipate rough weather or I'm making a passage. I carry 2 1/2 gals of gas in a vented locker and the dinghy room is not taken by a remote tank. I replace the lower end oil every other season. As small engines mostly still have carbs, 2 str may be slightly more tolerant of e-gas influences but either can be reliable if you treat them properly. I've had Yams of each type for more than 15 yrs, both free of starting problems so that covers the past 30 yrs. I run either until near stall if I don't expect to use it for a couple of weeks, and put a bit of stabilizer in my fuel over the winter only. Much depends on frequency of use, with either you must keep the cooling system functional. Silicon grease is your friend to fight corrosion. All small engines like clean air + fresh fuel. My outboard is used almost, yet not exclusively when cruising because my boat is kept at a slip. An outboard relied upon to commute to a boat on a mooring or serving on extended voyages needs more love and probably should be run until close to or actual shut down each time it used and then lifted clear of the water. If serving in salt water its best to flush with fresh when possible and all parts subject to backsplash should be sprayed frequently with WD-40. I've found these practices keep me free to deal with the other elements of yachting.

[rslifkin]

Keep in mind, the EPA didn't technically ban 2 strokes. Evinrude was selling larger 2 stroke E-TECs until 2020. Basically, the EPA tightened the emissions rules and the manufacturers decided that making small strokes meet those requirements wasn't practical compared to just selling a 4 stroke instead (that could meet the requirements more easily), so they just stopped making 2 strokes instead.

[SofaKingFishy]

I own a 15hp Yamaha Enduro 2 stroke that came from the Bahamas- and with my boat. It’s loud & rattly, but is easy to work on & gets my 1.5 AB RIB on plane with 4 souls aboard. That said, I’m serious considering replacing with either the new Mercury 5.0 Propane or an electric, just to eliminate any petrol on board.

[tamicatana]

I have seen a myriad Yamaha 2-stroke 15hp engines on cruising boats down here in Fla, and i'm pretty sure these people buying them in the Bahamas, (Minn's in Georgetown and Lightbourne in Nassau) and they must be getting parts in the US to keep so many of them running

That said, I've got an old 15hp 2/s Evinrude and I intend to keep it going. The light weight and simplicity outweigh the negatives.

[Adornan]

Just been through the same process. I wanted to believe I could make electric work, but a combination of price and range/recharge time put me off. In the end I bought a new Mercury 10hp two stroke which weighs only 26kg for my sea boat rib and a four stroke 2.5 Yamaha for my river boat, as it’s limited to 4 knots. If I was forced to buy a four stroke in a 15hp size I would be tempted by the new lightweight Mercury 15 4 stroke, rather than my old first choice of a 15hp Yamaha 2 stroke as the weight difference is no longer that great.

As already said you can’t beat the simplicity of a two stroke for maintenance, but tou can get pretty close in weight depending on the power bracket. I had a great Suzuki 2.5 four stroke which was only 13kg, not much different to the old two strokes. Where is is hard is in the 4-10hp range where the four strokes are quite a bit heavier than equivalent two strokes.

[ranger58sb]

Originally Posted by moseriw

Seems most of the people I see at the dinghy dock(s) frustrated over their engines not starting have 4 strokes hanging off the transom. Just saying

Oh yeahh says a victim of this 4 Stroke scrap

FWIW, our experience is slightly different. Most of the people we see having trouble are using carbureted dinghy motors, without regards to "strokes."

-Chris

[sailingbare]

As I type this, I have my 2nd two stroke 3.5 hp motor still in it;s shipping box that I recently ordered on eBay. I live in Central Florida. There was no issue purchasing the motor. I bought an identical one 2 years ago, and because I was satisfied it wasn't "junk" after hundreds of hours of operation I decided to get the second one as a backup. Price was WAY less than half the cost of any 3.5 hp 4 stroke I saw anywhere. I have seen the same motor I purchased on Amazon.com, but at a higher price than I found on eBay.
What constitues a 'ban' if you can point, click, and pick it up off the front porch a couple of days later?

[thomm225]

Originally Posted by Sailing Hanse37

Sorry to disagree somewhat. We bought a brandnew 5hp 2stroke in Surinam. Our advantages: weighs a LOT less than 4 stroke equivalent, mechanically much simpler… almost no maintenance needed, no oil change needed. diy is easy on these motors and they have a reputation of being indestructible. As for the fuel consumption: ours in 1 year is about 20 litres, so fuel economy is not important. We are on our first plug after 4 years, but i’ll maybe replace it in the coming months.

No oil change right, but you have to buy and mix every time you add gas.

My 4 stroke 5 hp 4 stroke 25" shaft outboard weighs 57 lbs and is easy to move.

Oil change once/per year (in engine and lower unit) in the mean time you just add gas.

One plug change in 11 years. One Fuel Filter change.

5-6 impellers and that's it for the maintenance plus adding Sta-Bil to the gas.

I've had like six-eight 2 strokes and two 4 strokes. The four stroke are way better and much more efficient plus they don't stink like a 2 stroke does