how to get the throttle rpms higher without changing a prop

[s2ntburd]

I have a 2005 50hp mercury 2 stroke. How do i get the rpms to go up? I know the big one is the prop, this is not the prop i have changed them and have a very low pitch prop right now and im still only at 4500 rpms. i think the throttle is going down far enough. Its like it stops at 3 quarts down. the boat has 4 or 5 adjustment screws on it, is there one to make it higher rmps at wot? or make the throttle lever go down more? i know the one at the bottom (3 in the pic)is for rmps at idle but im not sure what the other screws are for. could someone please help. or could it be the carb adjustment screws?

 

[dingbat]

Throttle travel doesnt tell you anything.

Pull the air box off the motor and check to make sure the throttle plate(s) are fully open.

If that’s not the problem you want to do a compression test

 

[Scott Danforth]

do a compression test first

 

[jimmbo]

I have a 2005 50hp mercury 2 stroke. How do i get the rpms to go up? I know the big one is the prop, this is not the prop i have changed them and have a very low pitch prop right now and im still only at 4500 rpms. i think the throttle is going down far enough. Its like it stops at 3 quarts down. the boat has 4 or 5 adjustment screws on it, is there one to make it higher rmps at wot? or make the throttle lever go down more? i know the one at the bottom (3 in the pic)is for rmps at idle but im not sure what the other screws are for. could someone please help. or could it be the carb adjustment screws?

Every one of those screws has a purpose, none of which is being the magic screw to get the engine to run faster. Granted if some buffoon messed them up and the engine is running poorly, resetting them to spec would improve performance. If every thing; compression, timing, carbs, sync between carbs and spark, fuel system, throttle cable adjustment, are all to spec, the transom height correct, and the boat isn't water logged, then you need a lower pitch prop

 

[Scott Danforth]

or more motor for the current prop.

 

[s2ntburd]

Can anyone tell me what each screw is for? Is there anywhere online I can get the factory specs from?
The motor was had a miss about 1500 rpms and sometimes would stall because the rpms would drop. I think I took care of that as the last 2 times out after some adjustments it was running ok but I just cant get the wot. Could it be a timing issue? Supposlily the engine was just rebuilt 2 years ago so I'm hoping the compression is good. I've tried a 12 pitch and ow a 9 pitch and cant get over 4500rpms.

 

[flyingscott]

Is your tach working correctly?

 

[jimmbo]

Can anyone tell me what each screw is for? Is there anywhere online I can get the factory specs from?
The motor was had a miss about 1500 rpms and sometimes would stall because the rpms would drop. I think I took care of that as the last 2 times out after some adjustments it was running ok but I just cant get the wot. Could it be a timing issue? Supposlily the engine was just rebuilt 2 years ago so I'm hoping the compression is good. I've tried a 12 pitch and ow a 9 pitch and cant get over 4500rpms.

I suggest you get a model specific factory service manual. It should explain which screw does what.
Since you have already mucked around making "some adjustments", any forthcoming advice from anyone will be wild guesses

 

[tacx]

You dont mention what your engines rpm rating is?