IQ 800 Piston Measurement Thread

[theshadowrider]

Measurments.

My piston skirts measured with 1000 miles on them
Left Side: 3.3373" Right Side: 3.3366"

Stock clearance is
Left Side: .00887"
Right Side: .00945"


Wiseco Stock piston replacement

Left piston: 3.3417"
Right Piston: 3.3416"

Piston Clearance with Wisecos

Left Side: .00447"
Right Side: .00445"

 

[rocket]

I had a "great debate" going on in my head over what to put back into the motor. I run Wiseco in some of my modded stuff and don't have any issues with them. On the other hand, I also just pulled a set of factory pistons that have a bunch of time on them and they don't look any worse than say the old 800s did with similar amounts of time on them. Nobody worried much about pistons in those motors - everything was about the crankshafts. As far as clearance goes, no way would I run a piston that size (cast or not) at the minimum clearance you quoted. The top end of that is about where I would start. For discussion purposes, the old 800s (VES and non) list .006"-.0074" for the service limit on piston clearance. I realize different motor and all, but it's still a cast piston 85mm in diameter. With a forged piston similar diameter, I set clearances around .007" as a starting point. Keep in mind that this is working at sea level, so the motors are making more HP, so everything runs hotter, parts expand more, etc.