crazypj
Split personality, I fake being smart
If mototune was right the factories would be doing the same thing.
Making ports smaller may not change max power output much but the increase in torque makes bike much (much) easier to ride.
Majority of open class/sportbike owners buy because of max HP, 1/4 mile time, and ability to finance rather than ease of use.
Port in relation to valve size is the important bit, many ports are 'too big' when really valves are too small.
It's easy enough to work out required airflow of motor for 100% V.E. then work out event time based on crankshaft degree's.
Reality will be different at all rpm, flow reversion at low rpm, not enough time at high rpm, etc
Bunch of us 'tuner types' had some discussions about it when I worked at MMI., I think Cl. 9 (performance/dyno/tuning) did some tests but I forget outcome (inconclusive results)
Oh, use a 1/4" shank 3/8" head 'rounded tree' carbide burr to narrow valve guide boss and work the long turn. Using one for cast iron or steel doesn't remove metal as quick as using 'correct' one but it makes controlling what your doing much easier. Just use a lot of WD40 every few seconds.
Something like this, cut shank down to a more reasonable length
http://www.eastwood.com/1-4-shaft-double-cut-6-burr.html?reltype=3
Making ports smaller may not change max power output much but the increase in torque makes bike much (much) easier to ride.
Majority of open class/sportbike owners buy because of max HP, 1/4 mile time, and ability to finance rather than ease of use.
Port in relation to valve size is the important bit, many ports are 'too big' when really valves are too small.
It's easy enough to work out required airflow of motor for 100% V.E. then work out event time based on crankshaft degree's.
Reality will be different at all rpm, flow reversion at low rpm, not enough time at high rpm, etc
Bunch of us 'tuner types' had some discussions about it when I worked at MMI., I think Cl. 9 (performance/dyno/tuning) did some tests but I forget outcome (inconclusive results)
Oh, use a 1/4" shank 3/8" head 'rounded tree' carbide burr to narrow valve guide boss and work the long turn. Using one for cast iron or steel doesn't remove metal as quick as using 'correct' one but it makes controlling what your doing much easier. Just use a lot of WD40 every few seconds.
Something like this, cut shank down to a more reasonable length
http://www.eastwood.com/1-4-shaft-double-cut-6-burr.html?reltype=3
