RMP'S

[BUSTENBASS]

Need some help. I have a mercury 150 xr2 that i have a 25p quicksilver prop on but i can't get but 5100 rmp's out of it and i am getting only 50mph at wot. it will come out of the hole great but the top end speed is not there. What prop do i need to try or is there something else to look at. I have changed plugs, foot oil new fuel filter the engine runs great with no mis at all so i am thinking new prop.

 

[TKbigbass]

Check with one of the local prop shops or http://www.bbcboards.net/zeroforum?id=11</p>

 

[Jason F-18]

Try going down to a 23p. That's what I have on my boat with a merc 150 xr6 and turn 5600 at 55 mph. You would be welcome to try mine sometime if I'm down at the ramp.

What are you running it on?

 

[BUSTENBASS]

oh forgot to say what boat it is on it is a 87 procraft 18ft

 

[lucky rapala]

do u have a jack plat and what size is it if u do 23 raker is a good start frankin marine has demo props he will let u try it his number is 842-6395

 

[EricM]

It does sound like you may be a bit overpropped with your current set-up, or in need of a jack plate. A prop shop is a great place to start!

 

[BUSTENBASS]

yea i have a 6" jackplate and i have already adjusted the height of engine where the center of the prop shaft is 2 1/2 in below the pad. should i try going up another 1/2 in with the jackplate.

 

[stratos21xl]

be really careful raising the jackplate, the higher you get on the jackplate the lower the water pressure will get unless the motor/foot has low water pick ups. Get the motor too high and water pressure drops too much...bye bye engine.

 

[fishnboy]

Try 23 tempest.

 

[wrechin2]

Sounds over proped for a 2L But make sure you are getting full throttle. Another thing to check is to make sure the lower unit is the correct ratio. This is easily done with a piece of tape and a 15/16 socket and ratchet. Remove the cowl and put in forward gear. Install the ratcher and socket on the flywheel and rotate 1 full turn until the ratchet is facing directlly towards the bow. Place a piece of tape on teh prop at the 12 O'clock position. Rotate the engine EXACTLY 2 full turns stopping where you started. If the tape is back to the 12 O'clock position you have a 2:1 lower and it would be the correct one. If the tape is at the 1-2 O'clock position then it is a 1:87 and will cause it to lug. Just my experiences.