Yamaha 2.5 HP Four Stroke

Bought 2022 2.5 hp , gonna make this short and sweet,,,,,,this motor is junk, sold my 1976 johnson 6 hp and 1985 Honda 2 hp to buy this Yamaha 2.5,,,,biggest mistake I ever made in my 40 years of trout fishing in Nova Scotia Canada!

Bought the newer 2015 version this summer used. Also have the 4 HP purchased new in 2002. The 4 HP has a lot more power to push our 27’ ULDB race boat over 5 knots easy. While the 2.5 HP works just well enough up to 5 knots maximum. The 2.5 HP is very fuel efficient at 4.5 knots.

The 2.5 HP has an extremely fine pilot jet that clogs easily. A partial clog will make a smooth idle at low RPMs difficult to achieve. All summer the motor started first pull - but required a higher than optimum RPM. Just brought home for storage, the motor stalled while being flushed. Problem was a fully clogged pilot jet. The ride home must have stirred up some debris in the float bowl. Used a very fine wire to push the clog out - as carb cleaner alone was insufficient.

Once all the various carb jets have been fully cleaned, the motor now runs like a champ. Oil change was easy. Leg oil change was easy. Carb took a few hours to liberate, clean, reassemble, and water tank test. Repainted small paint chips, waxed painted surfaces, and conditioned plastic. 100% worth the time and effort - as the motor looks and runs like new.

Was probably the reason why the previous owner sold this motor. Inconsistent low idle. Now fixed. We will use the 2.5 HP all the time moving forward as it is a 20” vs our 4 HP 15”. The 15” short shaft is however perfect on our inflatable. Know the pros and cons and how to fix them - and you should be good.

If you need a reverse gear and a bit more power - get the 4 HP. If not the 2.5 may be all you will ever need.

This is my sixth Yamaha. Good luck with your choice and a fantastic fishing experience.

Well, the title says it all.

The big trouble with this engine is the jets are thin like a human hair.

And if anything gets in them; they won't run right. That includes varnished fuel.

You can imagine my surprise when the motor would not start the second spring of use. And I was low on gas on my main tank! And I ran all the fuel out in the fall!

The solution is to only use pristine fuel, high octane is good, non-ethylene is best, then never dry run the engine. Keep fuel in it and always make sure to run the engine every 6 months, 4 preferred.

Mine was bought new three years ago to power an Avon inflatable used as a tender and has never given confidence. It has been prone to cut out at awkward moments despite having been service and some care taken over the fuelling. This year we are trying Aspen to see if this helps with fuel stability. In overall terms it’s been a frustration.

I have had this motor for three years. If you leave the vent on the gas tank open, water WILL get into the gas. When that happens it may run, but at low speed and only with the choke wide open. The only way to resolve this is to drain the gas tank, and put in water free fuel, then try to run it long enough to purge the water from the carburetor. This can take from five minutes to an hour.

It is amazing that this motor does not have an accessible carburetor drain screw. Ir is also amazing that the gas tank allows water to get in if you leave the vent open. Yes, I know I should be smart enough to close the vent, but it is very east to forget this. I have had small motors for many years for my dinghy, and never had this problem with any other brand, including Mercury and Tohatsu, basically the same motor.

I have this engine, bought new, still under warranty. The foot had to be replaced because is was leaking and it burned the clutch. Never worked properly. When you close the choke it stops. if you leave it open the revolution goes up then down then up.... I was told that it was the fuel but it was discarded after checking the fuel. The last potential reason or excuse is that the carburator is broken or dirty and this after less than 10 hours in 2 years of operation. If I would have known this I would never have bought this piecs of junk (and I am polite). I was told that a small screw is defective at the bottom of the motor foot so the clutch was repalced under warranty, for the rest I am waiting to see how much it will cost to "clean" the carburator.

The engine can't be relied on at all. Not easy to get going and stalls easily even when warm. I have had it from new and it gives my no confidence at all.

I have had it serviced and use clean fresh fuel all of the time.

Has been a good performing engine. Does well on a 10ft porta-bote although a slightly bigger HP engine would give better performance with two people in the boat. But I prefer less weight and can't expect 4HP performance from a 2.5. I've seen cheaper engines but you get more plastic with them and this model seems to be rugged. I have had no starting issues with this engine. Like any small engine, always run out the carb gas as much as possible. About one quart fills the tank and chances are you will need to refill if you are out all day. Metal prop and water pump/water flow appears rugged. Engine oil level indicator should probably be a dip stick and not the window which can be mysterious when first encountered (filling the oil to the upper edge of the opening is way too much) But once you see how the correct level looks,however, it works.

The Yam worked brilliantly from brand new and while we were on old petrol/gas formulations (without bio-component). Hovever since fuel now has bio-component in it, despite all my efforts to drain fuel out of the carbs before storing it, and using stabilisers, the Yam fails to start 75% of the time, until I clean out and rebuild the carbs. That in itself is tricky because five or six carb items are held together with two bolts, and I've lost parts overboard. Horrible to service.

I can send to a dealer for a service, leave it for 6 weeks and I have the same problem. Time and time again. I thought of buying new carbs, but this will only stall (!) the problem for 6 months, at 50% of the cost of the engine. Any bio-component in the fuel left for any length of time - a matter of weeks - will kill this engine. I have often thought of just heaving it over the side, but I like to think I am environmentally responsible, and my conscience has stopped me from doing it. The Yam is awful, but dealers must like it because it keeps coming back again and again.