Does my new rig need more prop?

I finally bought the '89 Vegas XT that I have been saying was "mine" for 2 weeks. What's the top end RPM supposed to run on a stock 200 XRi (EFI)? It's turning a 28" chopper at 7200 rpm right now, getting roughly 75mph. Isn't that too high of RPM for a stock motor? What could I expect from a 30" chopper? Maybe I could get the current '89 Quicksilver 28" re-worked... thanks guys!

[Jeff "Yammer"]

Your RPM doesnt match your speed.
I have a 91' V-king and at 7100 I am gatting 92-93
depending on wind speed.That is with a 28" Yamaha
Drag Prop. Check your tach to see if it is in the right pick-up position { dial on back }.

Hope this helps.
Jeff.

[Delta]

Hey Pyro:
Jeff is right.
Check out this prop calculator.
Your gear ratio is 1.87,and the best slippage you can expect is .10 .
Prop Calculator (http://www.rbbi.com/folders/prop/propcalc.htm)
I think you should be hitting the rev limiter before 7200,but I'm no expert.Did the previous owner have the ECU modified?You're not running the oil injection,are you?
Good luck,Delta

[jimmyb]

ditto what the others have said... you really cant hit that rpm with a stock 200 EFI motor

[Arizona Hotboater]

HEY WHAT'S UP? THIS IS DUCKY.
EVERYONE ELSE IS RIGHT, UNLESS SOMEONE HAS CHANGED THE SWITCHBOXES, YOUR MOTOR CAN'T TURN 7200 AND MAKE ANY POWER. MAX RPM ON YOUR MOTOR IS ABOUT 6200. EITHER YOUR TACH IS WRONG(IT SHOULD BE IN THE "12 POLE ALT" POSITION), OR YOUR MOTOR IS UNLIMITED AND YOUR PROPSHAFT HEIGHT IS WAY, WAY TOO HIGH( MAJOR SLIPPAGE ). I HAD THIS PROBLEM WITH MY LAST BOAT. MY 2.4 WOULD SPIN 7400 WITH A 28 LIGHTNING E.T. AND ONLY DO 75 MPH. THE HULL WAS NEVER DESIGNED FOR USE WITH AN OUTBOARD AND THE BOAT SIMPLY WOULD NOT TAKE A SET. ANYWAYS HOPE THIS HELPS.

[Techno]

I reversed the numbers check and your probably running 5,887 RPMs
Try checking the RPMs at mid speed and punch the #s in to see if the Tach is off. Try filling in to find speed (leave blank), and then to find RPM (leave blank). put 10(10%) in for prop slip
Or at 40 MPH you should get about 3,134 RPMs

I made a cheat sheet with the RPMs and speed for the props I have, this way I can just look at the sheet when I'm on the water, I also put different slips in to see if I was running more effiecent from a change. I made it at every 500 RPMs for 0, 5,& 10% slips. This way I could just look the #s up Guestimate between the slips. People have posted from 14% slip to about 6% calculated with GPS so they were acurate. Even if Your gauges are off a [u]little[u] they are still the same gauges and will report an accurate reading for this purpose.

I took it out for a ride today. 2-3 footers from the 30mph wind, it was terrible. (Michigan) With the 28" chopper, the tach reads 4500 rpm at 40 mph, neutral trim, jackplate all the way DOWN, so according to your calculations (thanks), the tach is messed up. It reads at or a little under 1000 rpm at idle. (seem normal?) It has settings 1,2,3,4 and 5 on the back, as a small plastic flathead screw head. It is set on "3" right now. I didn't mess with it. It has three lugs, each marked by a letter. G, I, and I forgot the other letter. I had to cover it up, cause it's going to rain & storm soon. I couldn't help but notice the "G" connector was disconnected from the tach, but even with it re-connected, the tach didn't behave any differently. Maybe the Tach is defective. Any ideas?
-Chad

[Liqui-Fly]

The G is where your groung should go. I is for the tach sending wire from your wiring harness which should be gray and the other is for power from a purple wire on the ignition switch. There may be another connector for your gauge light which is typically blue and located right next to the bulb. David

[Cp]

Put the ground on (make sure it IS ground - use an ohmmeter). Is the tach a Medallion? If so, turn the switch to 4. Cp

As far as I know, these are the stock gauges that Hydrostream put in the boat when they built it in early '89. It is a 0-8000 rpm tach. What do the 1 2 3 4 5 numbers mean on the selector, anyway? I think the previous owner was clueless, he told me that it ran 7200 rpm WOT, and I never though anything of it, other than it sounded high. But, there's no way it's actually turning 4500 rpm at 40 mph, jack down/neutral trim 28" chopper, and that's what it's telling me. The ground wire made no difference, hooked up or hanging loose. It looks cheesy. There's a ring connector loose on the lug, (no nut tightened onto it), that wire goes to another gauge, and a rubber booted 90-degree connector on the end of the lug, sandwiching the ring connector (no, I'm not kidding). The wire on the booted push-on connector goes to the metal frame of another gauge, an obvious ground connection. I get home from work 1/2 hr. before dark, so I might not get a good chance to mess with this thing again until the weekend. I visit the forums daily from work and from at home. -Chad