208 Adventure Top end

[Doc Stressor]

The engine was not as loud the last time I took it out.

So it was a bad plug or a loose ignition wire. I had an F150 on a Key West years ago that lost a cylinder. The first thing I noticed was the change in sound. I slowed down right away so I never noticed a loss of power. In this case, it was a bad coil.

If you hadn't yet heard the engine sound when it was running correctly, it is understandable that you would not have recognized the sound of a dropped cylinder.

 

[DennisG01]

So it was a bad plug or a loose ignition wire. I had an F150 on a Key West years ago that lost a cylinder. The first thing I noticed was the change in sound. I slowed down right away so I never noticed a loss of power. In this case, it was a bad coil.

If you hadn't yet heard the engine sound when it was running correctly, it is understandable that you would not have recognized the sound of a dropped cylinder.

I've only ever had a loose plug on stern drives, but there was never a change in sound (at least that I could tell). I wonder why the difference in an OB? Especially... what would cause it to get louder? Curious.

 

[Doc Stressor]

The best way to describe the change in sound with a 4 cylinder outboard is that the sound changes from smooth to rough. It's not necessarily louder.

It's pretty amazing how an engine can still run reasonably well with one cylinder not firing. I once had a 140 hp Evenrude 2-stroke that broke a wrist pin while offshore. There was a bang and a rattling noise. The engine continued to run with that "rough" sound. I ran back to shore at least 12 miles turning 4000 rpm. I check the compression after I got back and one cylinder had 0. When I tore it down for the rebuild I found the broken end of the wrist pin had worked its way into the upper cylinder cutting a groove in both the piston and the cylinder wall. The top of the piston looked like it had been beaten with a hammer. But the engine still ran and was able to push the boat!

 

[DennisG01]

That makes sense, Doc. The engines I've experienced that are down a cylinder have been V8s - no noticeable difference - not even rough. But they still had 7 good ones, whereas with a 4-cylinder, that's 25% down.

2-Strokes are beasts, for sure!

 

[Koakine88]

Jason, you may have misinterpreted what I wrote. I meant it as a POSITIVE thing. No money involved.

But, to be honest, expecting a small boat to be able to go WOT in rough conditions IS "user error". And, with lesser chop, you'd be able to use more up trim. Remember, you did mention that you initially didn't adjust the trim much.

If it was only windy, with little chop, you should have been able to turn 180* and go faster. Unless the plug gaps were WAY out - which they didn't look to be - a small "out of gap" measurement would only have a minsule effect. I'm not sure what you mean by "tighten throttle cable". Was there an issue?

It doesn't sound like you need a different prop - you mentioned you had a pretty heavy load in the boat and still got almost what the Grady specs are. But that brings up another point... have you always had a heavy load in the boat? That's something to have mentioned early on since that can have a dramatic effect on WOT speed/RPM... again, user error, if you did However, if you're going to be running with a heavy load most of the time - then, yes, go ahead and drop a couple inches. When you have a light load, just control throttle/trim so you don't over-rev.

Jason, DO NOT get the OFS4 15.25” 4 blade prop. I have the same boat as you (200F with hardtop) and it is too much prop for our engine. I ran that prop for 6 months and although it provided excellent grip and rough water performance, it just felt like it was straining the engine a little (hard to explain). I could barely get to 4,700 rpm’s with that prop and per factory specs you should be 5-6k WOT.

I ended up replacing the OFS4 with a smaller diameter prop in aluminum to test (quicksilver?) I think it was 14.75 or 14.5” with a higher pitch (lowest available The boat now still barely gets to 5,000 RPM and barely over if it’s glassy calm. I accept the loss in top end, as the one I got was the smallest diameter 4 blade I could find. I honestly think 15”+ is just too much surface area for the 4 cylinder Yamahas.
Ken at prop gods recommended the OFS4 as well, but warned it may be “too much prop” he was right.
My factory Yamaha 3 blade stainless prop was excellent for high speed runs and I definitely got mid 5,000’s for RPM’s but 3 blades just don’t work great in Hawai’i waters. Always choppy with big swells, I needed that grip and am willing to sacrifice top end for it. Boat gets on plane much easier than factory 3 blade and doesn’t fall off plane as easy with rough seas. That OFS4 is just too much…

 

[Peter A]

Jason, DO NOT get the OFS4 15.25” 4 blade prop. I have the same boat as you (200F with hardtop) and it is too much prop for our engine. I ran that prop for 6 months and although it provided excellent grip and rough water performance, it just felt like it was straining the engine a little (hard to explain). I could barely get to 4,700 rpm’s with that prop and per factory specs you should be 5-6k WOT.

I ended up replacing the OFS4 with a smaller diameter prop in aluminum to test (quicksilver?) I think it was 14.75 or 14.5” with a higher pitch (lowest available The boat now still barely gets to 5,000 RPM and barely over if it’s glassy calm. I accept the loss in top end, as the one I got was the smallest diameter 4 blade I could find. I honestly think 15”+ is just too much surface area for the 4 cylinder Yamahas.
Ken at prop gods recommended the OFS4 as well, but warned it may be “too much prop” he was right.
My factory Yamaha 3 blade stainless prop was excellent for high speed runs and I definitely got mid 5,000’s for RPM’s but 3 blades just don’t work great in Hawai’i waters. Always choppy with big swells, I needed that grip and am willing to sacrifice top end for it. Boat gets on plane much easier than factory 3 blade and doesn’t fall off plane as easy with rough seas. That OFS4 is just too much…

Just was digging around a bit on prop selection. wondering where you guys finally ended up on props for Hardtop 208 with F200.

Based on experience from my current Solas HR4 14.5x15p 4-blade, with PropGods recommendation I ordered a Powertech SCE4 14x14p 4-blade. 2021 208 with f200, hardtop, windlass, hull is clean and repainted. Prior owners switched out the original 14.25x17 Reliance 3-blade so I don’t have that to compare. The Solas runs 5000/5100 max fully trimmed out, 38-40mph, tons-o-grip holeshot, low speed plane has great holding power, some weird and very heavy torque steer at times coming onto plane and when taking certain head seas off front quarter, good cruising 3800rpm/23-25mph/3.7-4.1mpg and across 3500-4200 rpm range. Going past 3/4 throttle has no material impact on rpm and speed. Throttle cables and linkage are good. Engine checks out by Yamaha tech.


edit - after seeing a boat test video of a 215 with F200 and no hardtop, if the SCE4 14x14p 4- blade doesn’t work out I will try Reliance-style 14.5x15 3-blade that seems to work on the 215 with a stated test weight of 4,500lbs, which was able to turn 5800 rpm. I figure the way I run the 208 with a hardtop, that is close to my running weight with a 1/2 tank (2900 lbs dry boat + 500 engine + 250 fuel + 250? hardtop + 150 gear + 450lbs people = around 4,600.

 

[Peter A]

Installed the 14x14p Powertech SCE4 4-blade recommended by Ken at Prop Gods. Running solo with full fuel and canvas, 40 mph @5700rpm, did not need to trim out to the extreme. Overall the boat feels so much more lively. Much better acceleration and throttle sensitivity/control, and easier to trim, versus the 14.5x15p Solas HR4 that would struggle to reach 5,000rpm. Great running between 3600-4200, picked up a couple of mph and better MPG. At 3800 rpm, indicated 4.5 mpg and GPS 26mph. Not too rough but not smooth water. Prior ownerhad swapped out the OEM Reliance so I don’t have comparison to that unit.

When the boat is pulled for the winter I may raise the motor by one mounting hole (currently at 2nd from the top), seems like other 208 owners have had positive results with this adjustment.

 

[grunt]

When my 208 with a Yamaha 150 was losing power a couple of years ago... I checked the fuel filters, injectors and coils but found it was a bad spark plug
New plugs and it was back to normal

 

[Peter A]

Thanks for that reminder, I think I am running full power but the vent plate is buried. If I pick up a bit of rpm and speed with raising the motor, I’ll be close to 6000rpm and hopefully 42-43 mph. That should be pretty good for the SCE4 14x14 I am running. Very happy with holeshot, mid-range cruise speed and mpg, and maintaining low speed plane. Need to gather some additional data points and when the boat is pulled out for the winter raise the motor and continue making adjustments as needed. Would be nice to have the original Reliance 14.25x17 or a 14.5x15 to compare.