I changed the gaskets on my rocker boxes because the front one was leaking pretty good. I noticed the bike now runs a lot better and pulls harder. Do you think the two could be related? Is there a loss in pressure when you have that kind of leak that robs you of HP?

 

Where is TC? If you had a head gasket leaking you would gain some power for sure, in your case maybe you're not venting as much oil mist into the breather now, and also a sealed engine will perform better as the crankcase pressure is not as great, which is probably what was going on, when the piston is on the upstoke it will suck in air through the rocker box leak and on the downstroke it has to compress the volume under the piston, too much crankcase pressure can effect engine performance. Most HD drag racers actually run a vaccum pump to the crankcase to get a negative pressure.

 

Here I am

I was over worked by Springer and needed a time out

What John says makes sense, I fitted a system I made to a bike I had that caused a vacuum to the crankcase and it not only made the bike sound a little different , but it ran better from the vacuum. I can understand the principal of this theory, but I still don't understand why when a rocker gasket is leaking that it would cause a loss in power. It seems that the crankcase would just vent better and not have any adverse effects, whereas a vacuum would be lost and that would have an effect. I'll have to sleep on this one