Top end rebuild

[riverside]

I am rebuilding the top end of my ZR 580 and I was wondering what people think about having the heads ported and polished? Is this something worth having done? Does anyone know who does this in the St. Cloud area if I decide to have it done?

[hydro]

Having someone port the cylinders would be expensive for any gain you will notice. The heads would not need any work other than a good cleanup, since they have no porting. If you shave the heads for more compression you may have detonation problems with pump gas. My suggestion is just re-build it to spec and run it.

[Macgyver55]

I agree, any gain you might realize may go to waste especially if you are not familiar with tuning high performance engines.

Porting can also change your power curve and require changes to clutching, timing, jetting etc.

[Tyler23]

if you want more performance out of your sled. i would rebuild it to stock and look towards a clutch kit maybe dif gearing and making it lighter and hook up better. unless your racing IMO leave the most of the motor alone 2 strokes are pretty "picky"