woth a bit of research i found the suzis are a bit lighter and told they arent as thirsty, they both have a good name but depends on who you speak to

 There is some info on this and I remember some issues withe the dampers on 300hp Yamaha flywheels, I think others miight chime in on this one. Definitely worth investigating cos I was surprised Yamaha would let thios issue slide. Carnarvonite i think you know ? There is a requiement for the entire flywheel to be rerplaced at a certain intervall based on prior threads on this issue . Cos the flywheel is harmonically rubber balalanced ?? Correct me if I'm wrong.

I would like to say cheers, but good luck with a dodgy flywheel that causes catastrophic damage to the crankshaft if not replaced. Perhaps there has been a recall ?

Regardless, I have spent some time on a Powercat 30 ft that pushes 50 knts plus with two of these puppies  flat out, and these engines run sweet. 

just saying what has already been discussed. 

pretty sure Reece is right. The 350 have the balance issue. Bought a boat today with a yammy on it. I asked the same question and he said the 350 was the only one. Hope that helps 

The flywheels on both the 350 and 300 V8s have to be replaced, an alarm comes up after they have done 80 hours at a certain rev range.
There was a major problem with the exhaust manifolds corroding and allowing water to drain through the exhaust valves into the cylinder and down to the sump when the engine was shut off, not 100% sure if this has been fixed in the later models.
Fuel burn flat chat was 220 litres and hour = 47 knots on a 10 metre Naiad

Cannot comment on the V6s

The follow up from Yamaha WA and Australia was blood woeful enough so that I wouldn't even consider buying another if I had to

 both good engines but the Suzuki could be better on fuel. Repowered my boat from a 140 Zuke to a Lean Burn 200 and it uses less fuel at the same speed, The lean burn seems to improve fuel economy  cheers Ace

 I have the 300 Yam on my 7.5. Very happy with it. Generally cruise at 1.2-1.4kmpl at 24knots. 

Fully loaded to the monties sat at1.1kmpl. Which must have been 3.5-4t on water. 

Awesome holeshot for a 4 stroke.

V6 Good, V8 Bad

 Interested to see what the figures turn out to be. Will help me decide what to put on hull #2 haha

 I'm keen to see the consensus on both models.

I'm considering either the Suzuki DF300AP or Yamaha F300B for my upcoming build, and am finding it difficult to separate the two based on a desktop review...

Key distinguisihing features:

DF300AP - chain driven cam shaft, can swing larger diameter props (apparently), longer warranty.

F300B - 70A alternator, ~30kg lighter, better info display.

Both have their pros and cons.  

- Both have a relatively solid reputation in the marine outboard world.

- Both require 95RON fuel (Yamaha min is actually 94RON).

- There is a certain appeal to having a hard coating applied to the cylinder walls in lieu of steel sleeves in the F300B, but the DF300AP does apply an alumite coating to forged pistons which in my mind could have the same operational benefits.

- The F300B has dyno data which indicates it is a ~280hp unit, however, I have a feeling this was based on 89RON fuel in the US, hence why Yamaha now state 94RON fuel as a minimum.

At this stage I'm trying to look at real world fuel usage figures independent of each manufacturer because i feel their numbers are fudged and not an apple for apple comparison (how can each manufacturer provide test data which shows their unit is the most fuel efficient....), and i think it will come to that at the end of the day.  At the moment i'm waiting for a price on the DF300AP, but i've been advised there will be little difference.

Will post additional findings in the coming days.

Cheers.

Tom

 Shit ya done sum research there mate!! But like ya say by the time ya weigh it all up from what I can gather it comes down to what colour ya want on the back 

 Have you considered the new Suzuki 350 v6 with the duoprop? Seems to be creating a bit of a storm where they have been installed. 

 The majority of Sea Rescue groups and govt agencies are running Suzuki engines on their vessel. The reason is yamahas lack of reliability and getting parts is sometime near impossible particularly in WA.

 I f you like the idea of a 2 month wait for parts go the yammy

 Has anyone purchased or recently received a quotation on a Suzuki DF300AP fully fitted with the multi-function gauge?

What total price is to be expected?

Cheers

Tom

 For what it's worth as a comparison, I used to run an F250 (4.2L) on my Haines 650R (both 2014 models).  I was told on good authority at the time that 250 was really about 268hp and the F300 about 290, so not a huge difference.  It was also true st the time that the 300 required 98RON although I'm led to believe that this is not a requirement anymore of 300 so you should confirm this.  The hull was rated for 300 but extra few grand in cost and the 98 fuel requirement put me off.

I know boats and hulls are different but I used to get around 1.0nm per litre at 23-24kn cruise when loaded for fishing.  A full day of running to the trench from the river, trolling for six hours and return home I'd use 150 litres for a 110nm round trip.  In perfect conditions on the river I'd see 42kn.

PS be careful with US octane numbers, they aren't the same as ours.  Need to add around 4-6 to the US octane rating to be equivalent to our RON.

Im running the 300 yamaha on a 7.65m ali awesome have not had an issue. Think now days they are both very similar