1985 xst setup help.

[sasquitch007]

Hello everyone, I am new to this site and to outboards. I bought a 1985 xst last year. It has a 220hp mercury converted to carbs (wh22s), 6" setback manual jack plate,and just added water scoops. I have been trying to get more or at least normal speed for this hull. When I bought the boat it had a 26p big ear chopper on it. The best numbers I got with it 3 1/2" below the pad were 62mph(GPS) at 6000rpm. I bought a 25p trophy and raised the motor to 2 1/2" below the pad and got 62mph @ 5800 rpm. With the motor at 2 1/12" below the pad ,the trophy would shoot a huge rooster tail if I tried to trim at all. I have now added the water scoops and put the chopper back on and raised the motor to 2" below the pad. I could not get a wot test because the chopper now has a bad vibration you can feel through the hull. The more rpms the worse the vibration. I have talked to other about the vibration and most say that the chopper is out of balance? I never felt any vibration when the chopper was at 3 1/2" below the pad. I have talked with others that have owned xst boats and all of them say with my motor I should be getting a lot better numbers. I don't really know what is the right direction to go. Do I need more setback, a nosecone? I have great water pressure, with the scoops, 25psi at wot. Should I raise the motor? When I ran the trophy the slip numbers did get better. I thought I might put the trophy back on and run it at 2" below the pad. I am just not sure how high you can run a trophy. I know if could not trim at 2 1/2" below. I pretty sure I want be able to trim at 2" without a rooster tail. I have also been told that a nosecone will not help me until I reach 80mph? I greatly appreciate any help. I know this is a long post with alot of questions. I just wanted to give as much information I could. Thanks again for any help. Brad

 

[85allison]

I would get a low water pickup for safety and better set up. I have the same boat. I run my motor with the tip of the cone even with the pad. I have a stock 200 2.4 carb motor and with an allison cut 24 yamaha drag prop I ran 96 on gps. You will be able to reach 80 quite fast but the motor is far to low and you need 9" of set back.

 

[sasquitch007]

Thanks 85 allison. Have you had any problems with vibration . The chopper has a bad vibration at the current engine height. I have put the 25p trophy on but have not ran it yet. Does the nose cone make a big difference. I was told on scream and fly to get my slip numbers down before buying a none cone. I have installed the water scoops. I was thinking of buying the 2" spacers from bobs. With the spacers I would have a total of 8" of set back. Thanks for your help.

 

[85allison]

I would get the 2" spacers and get a nose cone, it makes a huge difference. Depending ont he prop you will get some vibration. Good luck, look for a nose cone and a good 24 Yamaha drag prop

 

[sasquitch007]

Thanks for the help. I have talked with your uncle I think? corona Mike on scream and fly some time ago when I first got my boat. You both have helped me alot. I will get the spacers and when I get the funds, a nose cone lwp from bobs. What is a fair price for a 24 Yamaha drag? Is the boat in the pic your new boat? Its very very very nice. What model? I really like my Allison, I just want to get the most I can out of it. Thanks again for your help. Brad

 

[85allison]

You can spend from 300.00 to 700.00 on a prop. I would look for a lower unit that has already been done. That is my new boat, it is an XB2002. You will get there with your boat. The guy I sold it to just ran 98 on the gps today with a modified 2.5 200 with a 15" mid and sportmaster. He was running a 27 mazco re3 allison cut.