I noticed today that my bike has compression release valves. The dealer must have installed them when I had the big bore kit, HTCC heads and pistons done. I never noticed this before because I usually drink beer while washing my bike, apparently little details escape me.

How do these things work? I understand the general principle. They seem to have two positions- up and down. You can click them up and down when the bike is off. However, with the motor running, they will only stay in the up position. Are these automatic valves or do I have do something with them when I start the bike? I'm assuming that because the dealer installed them that they are the Screaming Eagle compression release valves.

 

Depress both of them just before you start the bike. The compression in the engine will close them as the bike starts.

The purpose of them is to relieve compression while trying to start the bike and "hopefully" reduce the likelihood of munching starter clutches on engines with greater than 10:1 CR.

If you have them and have high compression pistons.... USE THEM!

 

Thanks. So depressed allows some air/gas to escape when starting?

Anyone have any idea what the compression ratio is for HTCC heads with the HTCC pistons?

 

10.5 : 1