Hi, great videos. Can you please make a video about expansion chamber variables. Carburatour size, port durations, compression... Which sections changes based on variable. Thanks
Carburetor size affects the burn time so the bigger the carb, the faster the burn and the lower the EGT. The higher the EGT the quicker the pipes return waves reach the cylinder. Jetting and compression affect exhaust gas temperature and its near impossible to calculate for that so it's best to measure the EGT which you can do with a $70 gauge (listed on my site). Rich jetting causes a slower burn which extends closer to the time of port opening so the EGT is hotter. More compression causes a faster burn and so makes the EGT less. Port durations interplay with the timing of the pipes return waves and that is best analyzed with a pipe calculator with return wave simulator (like mine that I sell at www.dragonfly75.com/motorbike/portsMS.html ).
Hi master!! I have a vintage trials bike (pistón port) which has 142 grades of intake, and 133 grades of Transfer, with 168 of exhaust (didn't measure the blowdown period). I think i have a lot of intake and Transfer time for a supposed low end torque bike, and i want to get a better low end, for what i thought about lowering the cylinder by milling It or installing a thinner gasket between the crankcase and the cylinder but....if i low the cylinder to get less exhaust and transfer time, i would get more intake port time, ins't It? So maybe It could not work properly. What do you think about this, or have you any idea to get a better low end? I really apreciate all your efforts to this beautiful and smokey world!
Just use JBWeld to raise the bottom of the intake port. But don't expect a huge difference. On my piston port engines I've gone all the way down to 110 degrees of duration and still they were very lacking compared to engines with reed valves. Get creative and do that.
that's probably due to a racer exhaust pipe. The mid range is weak due to a lack of diffuser return wave strength and too much baffle wave strength. A completely different pipe is needed.
Hi, great videos. Can you please make a video about expansion chamber variables. Carburatour size, port durations, compression... Which sections changes based on variable.
Thanks
Carburetor size affects the burn time so the bigger the carb, the faster the burn and the lower the EGT. The higher the EGT the quicker the pipes return waves reach the cylinder. Jetting and compression affect exhaust gas temperature and its near impossible to calculate for that so it's best to measure the EGT which you can do with a $70 gauge (listed on my site). Rich jetting causes a slower burn which extends closer to the time of port opening so the EGT is hotter. More compression causes a faster burn and so makes the EGT less. Port durations interplay with the timing of the pipes return waves and that is best analyzed with a pipe calculator with return wave simulator (like mine that I sell at www.dragonfly75.com/motorbike/portsMS.html ).
@@MichaelForrestChnl thank you. I might buy it.
thanks Mick
Hi master!! I have a vintage trials bike (pistón port) which has 142 grades of intake, and 133 grades of Transfer, with 168 of exhaust (didn't measure the blowdown period). I think i have a lot of intake and Transfer time for a supposed low end torque bike, and i want to get a better low end, for what i thought about lowering the cylinder by milling It or installing a thinner gasket between the crankcase and the cylinder but....if i low the cylinder to get less exhaust and transfer time, i would get more intake port time, ins't It? So maybe It could not work properly. What do you think about this, or have you any idea to get a better low end? I really apreciate all your efforts to this beautiful and smokey world!
Just use JBWeld to raise the bottom of the intake port. But don't expect a huge difference. On my piston port engines I've gone all the way down to 110 degrees of duration and still they were very lacking compared to engines with reed valves. Get creative and do that.
my kawasaki krr 150 have powerband like TM125 drop power in mid rpm how to get rid that problem?
that's probably due to a racer exhaust pipe. The mid range is weak due to a lack of diffuser return wave strength and too much baffle wave strength. A completely different pipe is needed.