On 5/8/18 Batman said "reversion is only caused by the piston moving up for the compression stroke and the intake valve still open . "

Take a look at this short video from S&S cycles.  It gives the lowdown on harmonic reversion related to drag pipes.

https://www.hotbikeweb.com/ss-cycle-drag-pipes-carb-jetting-troubleshooting-v...

I may not have inserted the link correctly so you may have to copy and paste into your browser.  Its an excellent video and gives a very clear and graphic explanation of why drag pipes don't work well in street applications.

Also, regarding "the piston moving up for the compression stroke", the intake valve is closed on the compression stroke.  I will concede that there will probably be some blowback through the intake at very low speed when the piston approaches top center on the exhaust stroke.

DBM there is some blow back (reversion ) in the intake anytime the motor is running the least amount at (ABOUT 3400RPM) where it develops peak torque ,consider that when the piston reaches BDC the cylinder is nearly full ,but the piston travels 48 degrees past BDC  compressing the fuel/air mix before the intake valve closes forcing some of the fuel back through the intake at rpm less than 3400.Above 3400 the speed of the piston doesn't allow time for full loading of the fuel/air mix and some exhaust gases remain in the cylinder, and again there is some reversion , torque decreases yet with higher rpm hp increases. when you talk about reversion your talking about the intake . when you talk about the exhaust your talking about (sonic) wave tuning. Two different animals.

On 5/9/18 batman wrote "DBM there is some blow back (reversion ) in the intake anytime the motor is running the least amount at (ABOUT 3400RPM) where it develops peak torque ,consider that when the piston reaches BDC the cylinder is nearly full ,but the piston travels 48 degrees past BDC  compressing the fuel/air mix before the intake valve closes forcing some of the fuel back through the intake at rpm less than 3400.Above 3400 the speed of the piston doesn't allow time for full loading of the fuel/air mix and some exhaust gases remain in the cylinder, and again there is some reversion , torque decreases yet with higher rpm hp increases. when you talk about reversion your talking about the intake . when you talk about the exhaust your talking about (sonic) wave tuning. Two different animals. "

Maybe we have a misunderstanding related to terminology.  I have always associated reversion with sound waves traveling back up the exhaust, through the open valves (overlap), and back out the carburetor.  The S&S folks refer to it as "harmonic reversion".  Key word, "reversion".  Maybe its a Harley thing.  I'm an old Harley guy.  So that's what reversion means to me.  I'm pretty sure you would agree that S&S Cycle is an old and accomplished performance parts manufacturer.  They got it goin on, lotsa records, great products, the whole enchilada.  I think they know what reversion is.

So I'm willing to entertain your definition of "reversion" (blowback starting at BDC when the intake valve is still open at the beginning of the compression stroke) as the source of loss of low end torque.  Hmmmm!  Let's see, LS cam makes more low end torque than DR cam.   Hmmmm! LS cam holds the intake valve open 48 degrees past BDC, DR cam holds intake valve open 42 degrees past BDC?????  Hmmmm!  How does the DR cam allow more of that fresh charge to blow back out the intake than the LS cam, since the DR cam closes the intake 6 degrees sooner?

Uh huh.  Difference in lift?  Like a whopping .020".  Wavy???  It's dependent on pipe length and occurs at a very distinct and narrow rpm range (usually at very high rpm with drag pipes).  Drag pipes work good on the drag strip (that's why they call em "drag pipes"), and they work crumby on the street (that's why they don't call em "street pipes").

So once again, if this so called reversion resulting from the intake valve closing point results in reduced low end torque, how does the DR cam allow more of that fresh charge to blow back out the intake than the LS cam, since the DR cam closes the intake 6 degrees sooner?

Cmon Batz, throw me a bone.  It closes the intake 6 degrees sooner.  How does your concept work here.  Never mind wavies, and HUGE variations in lift (WOW! One-half of one millimeter).  Six degrees less for the piston to cram that fresh charge back out the carb.  Six degrees less to compress the charge.  Why is the low end torque less on that 692cc, 10.?:1, DR cammed, drag piped, Fin Savage?  Why is that low end torque less than a stocker?  Why does my stock displacement, stock compression, stock carbureted (except jets), stock exhaust (32" header and all) engine feel weaker down low with that DR cam?

Oh! BTW, I don't have any misconceptions about "harmonic EXHAUST reversion" blowing back across the combustion chamber, out the intake valve, and backwards through the carb, and back & forth again & again at rpm below the sweet spot on those drags.  It picks up fuel both ways.  As it cycles back & forth at low speed, the charge gets so rich the thing will barely run.  Your wavy thing don't work down there at 2200 rpm.

Well...maybe an actual PSI reading will clear things up.

I am going to do some work on my bike this weekend, and it will give me a chance to get a compression reading on the 95mm Wiseco and Stage 1 cam.

DBM drag pipes don't work good anytime, If you watched the entire video they end up throwing the drag pipes in a dumpster. 2200 rpm was where the biggest slump occurred using drag pipes ,because the wavy didn't reverse until it reached the end of the pipe and therefore returned much to late and found the exhaust valve closed . Harley motors have much the same torque peak as our peak as our motors ,that is it occurs at about 3500 rpm not 2200rpm. the video I watched shows them installing a thumb screw near the outlet of drag pipe to breakup the wavy and prevent it from returning at all(. as it can also hamper performance if ill timed.) .this tended to relieve the slump at 2200 giving slightly better performance . the fact that you think that wavy tuning only occurs at higher rpm ,may be correct ,but it also occurs any time the motor is at the proper rpm( in all five gears.) as does tuning intake runner length. Does it stand to reason that if wavy tuning doesn't work at lower rpm that cylinder pressure would be higher and therefore intake reversion would also be higher?

Dave , might be because you have a stage one cam (is there any overlap? -I think not being it based on a stock cam ) and your compression is not 8.5 :1 but 10.5 :1 .         If DBM ,uses the DR cam in his bike with the stock piston and compares it with his stock test ,that should tell the story. I'd like to see the result even if I'm incorrect.

Thanks for the compression number Dave.  It's really healthy (195).  Do you have any issues with pinging or detonation?  What sort of gas do you run?  Do you have to use any sort of octane booster?  I have one of those 97mm pistons but am not ready to install it yet.  I have some more low hanging fruit to pick before I rip the jug off.  So much to learn, so little time.

Regarding my cranking pressure Batz, I was surprised.  It didn't change, (155 before, 155 after).