Too Much Prop?

Hello folks
Okay I'm running a OMC Hydrasport "V" bottom with a 1996 Johnson "Ocean Runner" Normal load is full fuel 85 gallons two adults and one 7yr old child and standard fishing equipment

Heres my problem
I start to accelerate pushing the throttle to about 3/4 which is about 3000 Rpm. It takes forever to get to plane, once it starts coming on plane I go to full throttle, the engine accelerates to about 3600. As the boat gets on plane the RPM's will build to 5100 but no more. the 5100 gives me about 32kts with relativly no wind and waves. I pull the throttle back to give me 4400RPM and it runs great about 25kts but if I push the throttle to full it takes it several MINUTES to get back to 5100. Now if for some reason I decelerate and come off plane, then try to get back on plane with the throttle at full the motor lags to about 3500 and will not accelerate even with trimming the motor up or down. I have to make small "S" turns and the motor will start to accelerate and finally after about 10 minutes it starts to come back on plane.
I'm a very experienced in mechanical things so I took the service manual for the engine, checked all the throttle rigging, all was in order according to the book. Just to double check, I have taken the engine cover off removed the "Air Cleaner" whils my wife drove I had her goto full throttle, the butterfly valves in the carbs are wide open, the timing is advanced to about 32degrees.
my thoughts are thers too much pitch in the prop which by the way is a 14 3/4 X17 I figure if I go to a 16 pitch it might accelerate faster getting on plane faster.
Any and all help would be appreciated
Brian

Re: Too Much Prop?

Several things come to mind. First we'll assume your motor is a 200 or 225. Never run that motor under a load with the air silencer off. That will lean it out and possibly hurt a piston. If the timing is really at 32 degrees it won't last long either. It should have already burned a piston. Start with the basics. Check compression and spark and let us know what you find.

Re: Too Much Prop?

Dhadley said:

Several things come to mind. First we'll assume your motor is a 200 or 225. Never run that motor under a load with the air silencer off. That will lean it out and possibly hurt a piston. If the timing is really at 32 degrees it won't last long either. It should have already burned a piston. Start with the basics. Check compression and spark and let us know what you find.

Click to expand...

Well sir, hello again. I haven't seen you in quite a while. Maybe we don't visit the same sites all that much.

For you folks new to the forum this is one of the original "Big Guns" on this site and his word is gospel. No brag, just fact!

Best Regards,
Mark

Re: Too Much Prop?

Did checks today after work. The compression after a 15 minute run with the garden hose connected, Cylinders were 1=121 2=119 3=122 4=118 5-122 6=121 Sorry I shouldn't read other things when I post, the timing is 8(eight)BTDC may mistake the engine is a Johnson150 Ocean runner
The spark will jump a .055 open air gap, and is solid blue so its good
I used my borescope to look in all the cylinders nothing I wouldn't call bad, no "Blue" cylinder walls, nothin along those lines.
Yes I'm a very experienced mechanic, but I'm new to boating a big 2 stroke engines

Re: Too Much Prop?

Thanks for the kind words Mark. I still check out the site a couple times a day, lots of good folks here.

Anyway, the 60* V6 is one of, if not the best design OMC came up with. Very good motor, lots of zip. 5100 is on the low side, we like to set those motors up as close to 6000 as we can. Rather than changing to a lower pitch prop we'd look at the set up first. A lot depends on which HS you have but generally speaking those are very good hulls.

Those are good numbers, everything seems good there. We might look at carbs next, just to be sure, especially if the motor had been sitting unused for a while. Then back to set up.

Re: Too Much Prop?

I have run the boat pretty good the last three summers, putting about a 1000(Thousand) gallons of fuel through it in each of the last three summers, so I'm sure its not bad gas. The carbs were removed three years ago, when I took posetion of the boat, which it set for three and a half years before I got it. The carbs were cleaned, all new gaskets and the float levels checked, everything was within spec according to both the manual I have and the guy at the local marine dealer(Hilton marine wilmington de) I'm lost I have never had this engine go above 5400rpms, and the "Hole shot" is non-exsistent