Any predictions for New Yamaha lightweight (LA) 4-stroke motors?

[rdownes]

With the newly released 70HP coming in at 260 lbs, and the existing 250HP motor at 505 lbs, any hope for a midrange (say 125HP, crossing fingers at 330-340 lbs) on the horizon? Has Yamaha leaked any more info on this new engine line?

[ridgerunner]

Subscribed- Isn't the 250 4-stroke Yammi closer to 600lbs? I hear lots of complaints from friends and family about my Merc 250EFI on my boat being too loud, smokes too much, too rough at idle, sucks fuel. But it is only 500lbs, If I repower I want the same power to weight ratio and the old numbers on weight had me stepping back to the 150hp in a 4-stroke. Unacceptable, so were the prices.

[whipper]

Nope the SHO 4 stroke Yammi is same as Merc XS.

[John.Vaught]

What scares me about them is all the moving parts. I can't imagine trying to rebuild one of those over head cam motors right now.

[sosmerc]

4 strokes aren't designed to be "rebuilt"........they are designed to last. If they do break.....it's going to be very expensive. I have owned alot of cars and trucks with 4 stroke engines....they have always run until I was ready to sell. I am a diehard 2 stroke guy for over 30 years.....but the 4 stroke outboards are proving to be very durable and dependable....and their performance is finally getting closer to equal with the best 2 strokes. Yes, they have alot of moving parts....but the pressurized oiling system is pretty reliable and gets the lube where it needs to be.
I think the next big step will be DFI 4 strokes in Marine applications....auto already has it, along with variable valve timing.

[Superbender]

I like to consider myself a 2 stroke guy thru and thru,but sosmerc is right they are built to last they have come a long way.

[ridgerunner]

Nope the SHO 4 stroke Yammi is same as Merc XS.

Thanks,
I see, but not in a 25" shaft. Offshore Yamaha 562lbs 25" Leg, the traditional High Power 250 602lbs. They are getting lighter. Direct injected 4-stroke would be interesting, I wonder what the R&D dept is working on now?

[John.Vaught]

I'm still scared of them.

My dads I/O supercharged BBC motors needed to be refreshed every 500-750 hours and those were 4-strokes too. I know how to work on a SBC and a BBC.

[VectorPat]

A blown Big Block is no comparison to a modern 4 stroke outboard.

[Bruster]

500 to 750 hours is pretty good for a car engine that was really never designed to be a boat motor and really never intended to have a blower bolted on top of it. Now how long might that motor last if they were engineered from the begining for this kind of abuse? 4 stroke outboards are just that, engineered from the get go to be outboards and they are built pretty good.

I'm still scared of them.

My dads I/O supercharged BBC motors needed to be refreshed every 500-750 hours and those were 4-strokes too. I know how to work on a SBC and a BBC.

[engineermike]

I thought I read that the new 300 Yamaha 4 stroke is 505 lb. It's now a 4.2 liter 6 versus the old 300, which was a 5.3 liter 8. I still can't figure out how they made a 4.2 liter 4 stroke 40 lb lighter than their own 3.3 liter 2 stroke, though.

[John.Vaught]

I am glad to see that they have lightened the Yamaha so much but I am still going to wait until all the bugs are worked out. As for engineering our engineers told us we could make a one piece upper wing skin and incorporate it into a production aircraft with all of us saying that it wasn't a good idea. We no longer use a one piece wing skin.

I think that these four strokes will need to be rebuilt at some point and it would be nice to see somebody offering that service. Yamaha and Mercury have always been good to our family but we have always waited a few years to see how a model was going to hold up.

[AwesomeBullet]

Part of the weight reduction was the use of sleeveless cylinders....will be interesting to see how that works in the long run...

[engineermike]

Part of the weight reduction was the use of sleeveless cylinders....will be interesting to see how that works in the long run...

I'm assuming they mean no Iron sleeves, but the bore should still be coated with Chrome, Nikisil, etc. There is a big weight difference there, but Id be surprised if they weren't already doing that.

[AwesomeBullet]

Correct, no iron/steel sleeves. They bore the aluminum block then apply a 'plasma coating' (their words in their literature) to the bores. I'm curious to see what happens in the future if something happens and damages a cylinder if their are no sleeves to replace.