highest compression on pump gas question

[Honda5]

looking for a little help for a friend that wants to drop in a new piston and want to find out what you guys with the z400 can get away with on pump gas. I put a set of hot cams stage1 in it. The cams should have a little more overlap then stock. So all you z400/kfx400 guys help out a fellow 400 rider.

[cataway]

12.5 :1 i ran 93-94 pump gas

[Honda5]

thanks

anyone else???
or does anyone know what the stock compression is?

[cataway]

what elevation are you at ,it can make a difference.
at 5000 ft you can run higher comp. on pump gas

[2muchquad]

i ran 13 to 1 on a yz motor without issue,liquid cooling makes this possible.A lot of peopl get too caught up in compression ratio assuming it is what it is said on the piston box,actual compression can/will vary especially with cam overlap so true 13 to 1 maybe questionable,i hear "you need race gas for compression over 11 to 1" mumbo jumbo all the time,most people dont understand these variables....whatever;)