I'm replacing base gaskets soon, and want to bump compression while I have it apart? What compression ratio(s) work well with EV27? I've heard 9.5:1, but for some reason my mind tells me to go bigger.

I'll also have the jugs punched out .020 over, and the heads gone though as well while it's apart.

 

I run 9.5:1 KiethBlack with a .20 over bore, ev27 and really like the way it rides and sounds. If you go with anything higher you may have to run octane boost or find really good gas. Keep in mind you will should strongly consider SF ignition if your bumping compression.

 

and don't forget to install the 'hayden oil fix' jets when you do your base gaskets

...provided you're using james or harley gaskets

 

I got cometic. Can't do the Hayden oil fix with these?

 

You won't need it with the Cometic base gaskets.

 

This is what Andrew's say's,

I e-mailed Andrew's about compression ratio's you can use with the EV13 & the EV27 & this was the response I got. And I quote:










I wouldn't go more, but that's me. Looking at doing the same mod's this winter. Ride Safe,
Harold

 

it's not so much that you don't need it with the cometic, it's that they won't work with them .... the hole in the gasket where the oil passage is, is too small

also, i had the cometic base gaskets on mine...and after about 500 miles the oil began to seep through....so got the 'hayden oil fix' and used stock harley gaskets

i've put about 800 miles since the fix and it's dry as a bone down there

 

I've put 10,000 mi. on a set of Cometic base gaskets and no seepage at all. I guess everyone has different results though.

 

believe me, it angered me.... i mean, before i tore the top end down to replace them i rechecked the torque on the head bolts and everything was spot on

the only thing i concluded was that i MIGHT have been getting false torque head readings because the cylinder studs were in the factory position and may have loosened slightly, thus jarring things

....so before i replaced the gasket with the hayden fix i flipped the cylinder studs...and so i bet if i reused cometics i'd have been fine, but just didn't want to take another chance

 

I rebuilt my top end 8,000 miles ago, with the ev27 I used wisego 10.1 pistons. Runs awesome, like a striped *** ape.
I always use 93 octane and stay away from ethanol, or if I do use a less high octane, I put in a boost. Plugs look great, and bike runs super.