185 sport 3.0 am I down on power?

Brandon185

New Member
Jul 21, 2018
19
Boat Info
2005 185 sport
Engines
3.0
I have a newly rebuild 3.0 that doesn't seem to have the top end it should I'm maxing out at 35mph gps at 4200 rpm with a new 14.25x19 black max prop. Freshly rebuilt carb, it idles smooth, has good compression, timing is correct and doesn't stutter. I've ordered a new cap and rotor. Seems like other 185 and similar boat are able to reach 4800 rpm and north of 40mph if only a little bit north. Anyone have any ideas?
 
Is that the prop Sea Ray calls for? I wonder what a 17" pitch would do for you. It would certainly get you closer to 4800 rpm.
 
That's the stock prop that came with the boat. I have a 17p prop that I have to manually keep from over revving. I get on plane fine with the 19p prop but it seems to run out of breath I the top end. Wot is supposed to be 4400-4800 but for some reason I can't get there.
 
Were you able to achieve the proper RPM and speed before you had issues with the original engine (you should have been able to)? Is the hull bottom dirty... at all? Is the speed GPS-based or speedo-based? That hull doesn't like a ton of UP trim, but are you trimming up to get best speed?
 
Were you able to achieve the proper RPM and speed before you had issues with the original engine (you should have been able to)? Is the hull bottom dirty... at all? Is the speed GPS-based or speedo-based? That hull doesn't like a ton of UP trim, but are you trimming up to get best speed?

I bought the boat non running and just finished rebuilding the motor so I don't know what it ran like previously. Hull is clean, speed is gps and I trim up to max speed.
 
I run the same prop actually it's a 14.5 x 19, My WOT is the same and I reach about 4700 with that setup. I'm not carb'd
That's what I'd expect. There must be something holding it back.
 
I've run that model many times and you can definitely break 40MPH - so the reports you've read about that are correct. I'd say just go back over what you did and be sure timing is correct, plug wires are pushed on all the way, carb is correct, etc, etc.

Just for kicks, try running with the fuel cap off - just to verify that you're not getting a slight vacuum from a clogged vent. I honestly wouldn't expect this... but you never know. You could try eliminating the fuel tank/lines all together by using a portable tank plumbed in. But I would think that if fuel was the issue, the engine would start to stumble or run rough at the higher RPM. Speaking of fuel... is it old?
 
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I emptied the fuel tank before running it and filled with fresh gas. I'm going to replace the cap and rotor tonight. In neutral it actually feels slow to rev but I may be reading too much into that. Maybe it's not getting a strong spark.
 
Are the existing cap and rotor obviously bad? It's usually pretty easy to tell. Are plugs/wire good? Plugs gapped correctly?
 
Are the existing cap and rotor obviously bad? It's usually pretty easy to tell. Are plugs/wire good? Plugs gapped correctly?
Checking all that tonight. I don't have new wires but existing ones aren't obviously bad.
 
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Well the cap and rotor look new. It was probably the previous owners last ditch effort to make it run.

The plug gaps were all about.015 too large. Don't know if that's enough to make a big difference but it's something. Here's what the plugs looked like.
 
So I had checked the base timing and the intial advance but I hadn't checked the advance at higher rpm's looks like my advance is only going from 12 degrees at idle to 16-18 degrees at 3000 rpm. Does that mean my ignition controller is bad?
 

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