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I have a zenoah 260m with a CNC machined Gizmotors 29.5 cc cz-1 kit (7.2 hp with 3 FP of torque) I have a proboat Black Jack alum Pipe with a no leak flange and "O" ring cooling around the header. I am running a 19LB 49" cat vee hybred hull. I am using a measurement from the center of the header to the center of the cone of 11.5". If I measure from the center of the exhaust port at the motor and follow the center of the bend including the leak proof water cooling flange it measures 13 and 1/4" I can't seem to get the pipe to work. what should I start with? thanks bentoad

Many things affect pipe length. Best to start long. If that motor has 3ft.lb. of torque, it should have a very broad torque curve and tuning the pipe should be easy. If you don't have enough torque to get the motor on the pipe to begin with, then try less prop.

If you don't want to go through all of that however, just pick up a Quickdraw Pioneer 29. It comes with a pipe already optimized for 18,000 RPM, much better bottom and midrange torque and 8.5HP to boot. It's not necessarily about peak HP, it's about power from the bottom end up. Propping it will be easy.

I am not familiar with that pipe, buy assuming this is a zero band single-stage pipe on a 7/8" header. The 13.25" centerline measurement sounds too long to me on such a pipe. I would think probably about an inch shorter is where you will end up. Start taking it in 1/8" at a time and see what it does. Trim the header when you get closer to optimal setting. In the meantime give yourself about an inch of extra header to be able to pull back if required.


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I Have a steel pipe from Gizmo. Steel Victory pipe. I read this article and did what it said. No go. So I called Gizmo. This is what they said . The band is 11.5" after the bend on the manifold . I am using a 105* header. I am 11.5 " from the plug strait back to the band. Much better results. They said if you are running a 90* header bring the pipe all the way back to the bend. Now in this article it says to bring the pipe in. With the victory pope you want to lengthen it. Or go out .. Not much. That is where I am out. Going to the pond later to do some testing and tweaking later. Hope this helps you out

thanks guys for this article -found it to be a big help-as for changing the length of your pipe regarding the size of your prop i had no idea .(so much to learn)
thanks again