simo said:
Some one correct me if this is wrong
That 0.02 will drop to effectively 0 once warm so the rockers are pushed on the valves not rapping on them like a hammer
If you imagine opening a door by pushing on the handle with your hand or punching the handle with your fist
both might work but the second way will wear out either your hand or handle pretty fast
The lash for our race cam is .006" and it will be interesting to see what the rocker arms and valves look like when we pull it.
What is fantastic about this forum is that what we are learning on our string is being supplemented by this string.
We learned that cylinder pressure is impacted by the amount of TIME that there is overlap between the intake and exhaust valve both being open together. So when we tried to kick start it we had lower cylinder pressure than when we ran it on one cylinder at 4000k RPMs. Now if you look at the duration of overlap that booth valve being open on a stock cb175 cam it is greater than the cb200 cam. Hence the cb175 was able to scavenge better than the 200.
It will be interesting to see if shifting the timing event with the valve lash on both the intake and exhaust impacts cylinder pressure and then changing that event by having different lashes for both the intake and exhaust...and folks that is why Smokey walked down to the dyno store.
And the Honda engineers said, "let's make Variable Timing and Lift Electronic Control" wow I didn't know it was about beating the tax man. http://en.m.wikipedia.org/wiki/VTEC
"Due to the behavior of the working fluid (air and fuel mixture) before and after combustion, which have physical limitations on their flow, as well as their interaction with the ignition spark, the optimal valve timing, lift and duration settings under low RPM engine operations are very different from those under high RPM. Optimal low RPM valve timing, lift and duration settings would result in insufficient filling of the cylinder with fuel and air at high RPM, thus greatly limiting engine power output. Conversely, optimal high RPM valve timing, lift and duration settings would result in very rough low RPM operation and difficult idling. The ideal engine would have fully variable valve timing, lift and duration, in which the valves would always open at exactly the right point, lift high enough and stay open just the right amount of time for the engine speed in use."
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