So I ride a 50, one cylinder, no exhaust valve, all port. I have altered it from stock with a higher compression piston, a pod filter, carbon fiber reeds and a rejet. Recently I noticed that the o ring on my head pipe was blown and crud was spitting out where it was bolted to the head. i replaced the ring and sealed it back up and the following condition now presents itself.
water temperature is increased on average as much as 5 degrees.
the bike lays down at the top like it's choking.
I have a new plug in there and I believe the main jet to be just a tiny bit too big but when the exhuast was leaking it pulled solid all the way to redline and would happily hum along sitting there throttle cracked wide open. only after the o ring was fixed did it start losing power up top.
I have a theory and I wanted to present it for critique by those here with chamber building knowledge.
I think the factory pipe is too small. The bike now flows more air through the engine than it did off the showroom floor. What I sort of understand about chamber design is the following. (stop me if I am wrong)
1. Sound waves leave the engine, hit the reversion cone and bounce back shoving the escaped incoming fresh charge back in at the right time as the piston closes off the exhuast port.
2. These waves pass faster through a denser medium so a chamber of the same dimensions reacts at a different rate depending on the pressure of the gas contained in it.
Taking this basic theory and applying it to what I am seeing I conclude that.
1. The repair of the o-ring has increased gas pressure thus changing the speed at which reversion occurs making the pipe "too fast".
2. This is packing the intake charge back in alright but also a lot of spent exhuast causing chamber temps to increase and the charge to be contaminated creating both the temperature rise in the water and the loss of power.
If this in fact the case I believe that means I need to either lengthen the belly of the pipe to retime the pulse or put a larger stinger on it to lower exhuast pressure. Am I on the right track?