With all due respect i have been building and tunning two stroke engines for mor than 60 years and I take exception with your explanation. The power valve in any two stroke is a variable timing exhaust valve. When the valve is closed the engine preforms more like an enduro with higher compression and a longer power stroke. when the valve opens the compression is lessened and we move more exhaust out which creates more revs. You want high compression for torque and less so the engine can rev. In the old days you would widen and raise the exhaust port to gain horsepower, but we would loose bottom end torque. The power valve gave us the best of both worlds which we didn't think was possible at the time.
I am a visual learner, thanks Tyler. Have you done or could you do a video on setting a baseline for the valve and how to adjust for stock and performance pipes and reeds. Thanks again.
Any mods like this for a 80-125cc 2 stroke? I love the weight of the 2 strokes as a wife bike but the 2 stroke MX hit is really undesirable for a trail bike. Let me know what ideas you have?
@@tspmoto1134 No problem, it is a great video tutorial. I did notice some negative nonsense in the comments. But regardless of that I'm positive that anyone with a KTM or a Husqvarna that wasn't sure how easy it is to adjust the power valve, if they saw the video is aware now. I think it's awesome that some riders still share with others.
I also has a substantial effect on intake charge and static compression. My personal opinion is that it would have been much more credible to just state that raising the port height adds top end power. Trying to simplify a complex idea doesn't make it easier to understand.
I was mostly trying to explain how to make adjustments without making the video to overwhelming. Most people don't care about the nitty gritty, they just want to change a spring and turn the screw to make themselves feel better.
If I ride a 250 tc on some hare scrambles tight stuff what option on spring and adjustments ? Any thoughts is there a trail red? Not sure i heard that - thx
please forget that fucking "backpressure" word... power valves partially close the exhaust channel to simulate a shorter exhaust opening (in crankshaft degrees), because at low rpm's there is not much exhaust gas volume that needs to be evacuated, this effectively increases the power stroke some 10-20° longer so each and every combustion process has more time to push the piston down. that's why this gives you more power in low-midrange.