Compression Question?

[WC820]

I have a Built 900 twin in a Light chassis. its set up for the mountains But I hasve the clutching for a ZR at sea level. I did a compression check its 155psi Per side right on the button. Can I get away with mixing in some race gas and play with it around here I figures Id jet it lil fatter than a zr 900 and watch the digitron Anyone have some Input on 155psi at sea level???

 

[Sledbrain2]

Well I am not an engine guy but I believe 87 octane is 120 psi 92 is 130 ish 13 to 1 compression. I run a 15 to 1 head in mountains with 92 above 6000. Here at home I use 50/50 race gas mix an I do not hold the throttle for more than 30 seconds just to be safe. I do no know where 15 to 1 compression is for psi but I believe it is close to 155 or 160.

 

[diggerdown]

It would depend a lot on your squish design, porting and timing. Stock 900 runs around the 150 mark at sea level. Iowa must be around 1000' so 92 octain with good jetting should work with a stock engine but I don't know what you mean by "built".