How do you repair a non working speedometer?

[KeepsTheBeerAfloat]

Alright folks, need a bit of help here. Picked this boat up a month ago for a steal. Everything runs like a champ and after some elbow grease on the gel, it shined right up...however. My speedo does not show accurate. As I understand from the previous owner, the GPS hit the thing at 60. Well my speedo is oviously off because it only shows it about 40 at WOT.
And no, it's not because the boat only goes 40. Anybody had to replace a speedo? My neighbor was saying the speedo on a boat works with a needle or finger in the water, so if it's not showing correctly, then the needle is gone.
Can anybody help me out here?
Much grass!

[YeLLowBoaT]

there should be a little deal that drags on the back of the boat... it should be attached by a hose up to the speedo. water presure from the pick up goes thru the hose and to the speedo. some times the lines/ pick ups get cloged. try taking off the line and running just over plane and see how much water its coming thru. it should be spraying pretty good.

[KeepsTheBeerAfloat]

there should be a little deal that drags on the back of the boat... it should be attached by a hose up to the speedo. water presure from the pick up goes thru the hose and to the speedo. some times the lines/ pick ups get cloged. try taking off the line and running just over plane and see how much water its coming thru. it should be spraying pretty good.
Okay, let me start this again...LOL.
I just got my first JET. I also have an old Kona with an I/O, so I'm reallly realllly new with the jet. The grate under the hull at the back is then the "pick up"? I would assume then I should look into the grate to find this hose? Don't mean to sound naive, but I'm a visual learner, so I'm going with what I know of the boat.
Next , on running just over plane, what am I then looking for?
Don't mean to sound green...I've completely rebuilt my I/O's top and lower unit, and done some of the engine work...however, the jets are new for me.
If you guys can help a "green" kid on here (who am I kidding...I'm not a kid anymore) I am certainly humble enough to ask for help.
Much appreciated!!

[rrrr]

Speedometers aren't needed in a jet. Just tell everyone it "does 82 MPH, that's on GPS".
If you ever decide to sell it, put it on eBay and up the number to "100+ MPH, that's on GPS"
:D :D

[KeepsTheBeerAfloat]

Speedometers aren't needed in a jet. Just tell everyone it "does 82 MPH, that's on GPS".
If you ever decide to sell it, put it on eBay and up the number to "100+ MPH, that's on GPS"
:D :D
Yeah, I used to do that, then my jackass buddy showed me what 92 felt like in his Rogers and told me I better never lie about how fast my boat was going again. So, I'm fixin' to replace the gauges as they're pretty ancient, and just figured if I was going to replace them, I would like them to be working. Maybe I can get a 100MPH speedo and "fix" it so that I can lie to my friends in the boat...then when that Scarab blows by me at 105, I'm going to have to let them know that "that particular Scarab" does 165...LOL.

[YeLLowBoaT]

Okay, let me start this again...LOL.
I just got my first JET. I also have an old Kona with an I/O, so I'm reallly realllly new with the jet. The grate under the hull at the back is then the "pick up"? I would assume then I should look into the grate to find this hose? Don't mean to sound naive, but I'm a visual learner, so I'm going with what I know of the boat.
Next , on running just over plane, what am I then looking for?
Don't mean to sound green...I've completely rebuilt my I/O's top and lower unit, and done some of the engine work...however, the jets are new for me.
If you guys can help a "green" kid on here (who am I kidding...I'm not a kid anymore) I am certainly humble enough to ask for help.
Much appreciated!!
there should be something that looks like this( or simlar,1st make sure its in the down postion)
http://images.westmarine.com/full/10834_f.jpg
there is a small rubber hose coming off it... fallow that hose up to the back of the guage. take the hose off and 1st try blowing back thru the hose to see if any thing comes out of the pick up. leave it removed and go about just over planing speed( 2.5k-3.5k RPMs) water should be coming out of that hose pretty good. if not, make sure there are no kinks or clogs. reattach the hose and try again, some times thats just enough to blow out what ever was stuck in there.

[KeepsTheBeerAfloat]

Sweet. Thanks Yella!! That will be a huge help.
Letcha know how she goes when I get around to it next weekend!!