Boat seems to be missing 10 mph and 700 rpm

[Destroyer]

Have you done a compression test of the engine after it was warm? If we presume that it's getting the proper amount of fuel and air then compression and timing are the only two things left on the engine that could be effecting the power. Also, you still haven't done a lower final drive ratio test. And what spark plugs are you using?

[THEFERMANATOR]

I think you need to try another tach 1st. 31 knots at 5100 is still pretty high prop slip at 18%. You could easily have a bad tach throwing off your calculations.

[Striper80]

Originally Posted by Destroyer

Have you done a compression test of the engine after it was warm? If we presume that it's getting the proper amount of fuel and air then compression and timing are the only two things left on the engine that could be effecting the power. Also, you still haven't done a lower final drive ratio test. And what spark plugs are you using?

Yes, compression is good and the plugs are correct. The timing may be off as I don't have a test wheel so I set it cranking. Assuming the tach is correct, which I've been questioning, the idle is too high so the timing is off. The boat is idling at 1000 rpm.

[THEFERMANATOR]

You CANNOT set the timing cranking the engine over. There is spark advance built into the ignition module that starts ramping up around 3000 RPM's till 5000 RPM's. The other problem is there is a 6 degree timing advance during cranking until the engine has run for 5 seconds and has reached roughly 120 degrees. You do not need a test wheel to set timing. If you can get it up to 4500 or so on a trailer, that is ALOT better than setting cranking. Not setting the timing right is a GUARANTEED way to burn that engine up. It calls for 18 degrees, if you go over 19.5 degrees, it WILL melt a piston. Even so much as 19 degrees is playing with fire. Most who set these engines up set them to 17-18 at 6000 RPM's. you're better at 17 degrees than 19 degrees. But if you set it to low, it will foul out, carbon the rings up, then you'll stick a ring, and BYE BYE cylinder(some ran at 14 degrees, but they were jetted for it, had MONSTER carbs on them, and were meant to run at 5000+ for sustained periods of time). Get your timing set correctly before you go any furthur unless you want to be buying a new engine. You're playing with fire, and it WILL burn you here.

[Striper80]

My boat has a cdi power pack on it. I thought with this one you were able to set the timing cranking by removing the plugs, grounding the plug wires, using a spark tester, removing and grounding the temp sensor wire, and backing it off by 4* total advance? I'm going to either take it to a mechanic to have them set it or do it at the ramp.
I originally took it to the ramp near my house to set it but the tide was too low to run it on the trailer without dunking my truck. Now the boat is at my marina and the ramp is steep and slippery so I'm not too keen about doing it there. I'm not too keen on paying $145 minimum to the mechanic either. Hey we all have to make a living, but I hate having anyone touch my stuff.

[THEFERMANATOR]

Originally Posted by Striper80

My boat has a cdi power pack on it. I thought with this one you were able to set the timing cranking by removing the plugs, grounding the plug wires, using a spark tester, removing and grounding the temp sensor wire, and backing it off by 4* total advance? I'm going to either take it to a mechanic to have them set it or do it at the ramp.
I originally took it to the ramp near my house to set it but the tide was too low to run it on the trailer without dunking my truck. Now the boat is at my marina and the ramp is steep and slippery so I'm not too keen about doing it there. I'm not too keen on paying $145 minimum to the mechanic either. Hey we all have to make a living, but I hate having anyone touch my stuff.

You can ONLY set the timing with the engine running. It needs to be fairlyclose to 5K RPM's for it to be accurate. Wot timing will have no bearing on idle timing, so if that is off you will need to set the idle timing. Also keep in mind the fuel mixturemust also be adjusted to get idle speed correct as 95+ has adjustable carbs.

[Striper80]

Originally Posted by THEFERMANATOR

You can ONLY set the timing with the engine running. It needs to be fairlyclose to 5K RPM's for it to be accurate. Wot timing will have no bearing on idle timing, so if that is off you will need to set the idle timing. Also keep in mind the fuel mixturemust also be adjusted to get idle speed correct as 95+ has adjustable carbs.

I thought only the adjustment was the low speed mixture? Isn't WOT handled by jetting?

[THEFERMANATOR]

Originally Posted by Striper80

I thought only the adjustment was the low speed mixture? Isn't WOT handled by jetting?

Wot fuel mixture is handled by jetting. The carbs are adjustable for low speed mixture which can effect idle speed. I was talking about the timing only being able to be set with the engine at 5K rpms. If you can only get to say 4500, then set it to 16-17 as it will advance some with more RPM's. Timing is probably the most critical aspect to that engine, and it must be set at the correct rpm's, with a good light, and you need to be certain the pointer is dead on tdc as well. I've seen alot of these engines come back from supposed top shops running like crap because they didn't set the timing correctly, so they set it low to be safe.