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ContinuousWave: Whaler Performance
Mercury 125-HP 2-stoke Classic: Maximum Crankcase Speed
|Author||Topic: Mercury 125-HP 2-stoke Classic: Maximum Crankcase Speed|
posted 08-02-2004 02:16 PM ET (US)
What is the maximum crankcase speed on a 1996 Mercury 125-HP 2-stroke Classic? I have recently aquired a 1996 model.Thanks, Dave
posted 08-02-2004 03:27 PM ET (US)
WOT is 5250 I believe.
posted 08-02-2004 03:46 PM ET (US)
Thanks Big, I am turning about 5000. Do you think I should try a different prop to find the rest of the rpms? Dave
posted 08-03-2004 10:45 AM ET (US)
posted 08-04-2004 04:19 PM ET (US)
If 5000 is lightly loaded I would go down 2 inches in pitch and gain 300-400 rpm.
posted 08-04-2004 06:02 PM ET (US)
Thanks Nick and Bruce. By lightly loaded do you mean boat weight? The boat weight is about 1500 lbs. I have trim tabs, also. Dave
posted 08-04-2004 08:23 PM ET (US)
Increasing the engine speed to 5400 would put it above the maximum of 5250--probably not a good idea to run that engine above 5250. The in-line four cylinder without balancing shafts is not a high-rev engine. I am sure you can run that engine at higher speeds, but the very low rating of 5250 tells me there is a good reason not to.
posted 08-04-2004 08:43 PM ET (US)
Max torque at 4800, leave it were its at. what prop are you running? MartyD
posted 08-04-2004 10:29 PM ET (US)
Lightly loaded is less than a six pack! ;)
posted 08-05-2004 07:15 AM ET (US)
I had to check the prop size while the boat is on the lift. I can find the number 23 for the pitch but may have to remove prop to find the dia. Dave
posted 08-05-2004 10:38 AM ET (US)
I have a 1995 125 Merc. I have run it as high as 5600 for short spurts with no bad results. That being said max HP is supposed to occur at about 5000 rpm. My recomendation would be to prop the boat so that you can get to 5250+ at your lightest total boat weight when the weather is cool so that as you load the boat up with people and equipment and the temperature goes up in the summer causing rpm to decrease the available HP and Torque will be higher. That will give you a stable operating point.Dick
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