2.5 260hp

[vision]

im new to this site,i have a couple questions for you guys i have sea star hyd steering is it normal to steer hard to the left.also i have 96 stv is it normal to have a porpoise about 70mph. one more question how can i tell if i have top pinned pistions, thanks very much for your help.

[Eagle One]

Only way to tell if you have top pinned pistons is to visually look at the piston. It will have both ring gaps in the same location and the alignment pin comes in from the top. THESE were not standard on the 260's with exception to a very few of the later models just prior to the 280's. Hard to steer left sounds like a torque issue and may be caused from the engine being too high, a particular style prop, no torque tab on the lower unit. The porpoise at a particular speed can be again, engine height, prop, set up, weight distribution or some other issues related to the hull itself.

[vision]

thanks for answering questions. prop is a 28 pitch lighting et , propshaft is 1 inch above bottom of boat, it does have a torque tab its a factory sportmaster .also do you recommend any other props, looking more for acceleration more than the highest top speed.

[ddipert]

On the porpoising issue. Check setup. How much trim do you have when porpoising? Prop shaft height? Weight of the boat could also be a cause. Then there is the normal porpoise that you should be able to drive through and the boat will smooth out after you get enough air under it to fly it.

Look for a smaller pitch et or Yamaha drag prop. Smaller pitch will give you better low end acceleration. Watch your Tach make sure your not over revving the motor.

[Carter Powell]

Sometimes the factory torque tab needs a little help as in more material added to give it more sweep to the right. When you are running a surface style prop and half of that prop is out of the water that prop is really trying to rotate on top of the water like a runaway wheel and it pulls the steering wheel to the right a it trys to rotate to the right on top of the water. Even good hydraulic steering will not stop the torque, only lessen what you feel as you turn left. Sometimes the only way to neutralize this torque is with extra material added to trailing edge of the skeg.

Carter Powell

[mach351]

STV's just do that at that speed. It's a build up of air pressure then a "burp" out the back. Usually the only fix is to faster or slower, in my experience anyway.

[vision]

thanks for all the information .