vs what? Why not talk about something instead of talking about nothing?

 

actually, you DO want the scavenging to suck air. The scavenging is happening in the exhaust (exhaust pulses are not smooth, that's why they are called "pulses"). The, basically, vacuum created by the lower pressure of the end of an exhaust pulse sucks the unburnt fuel/air out of the combustion chamber, allowing a fresh charge to take it's place (and actually pulling it in). Fresh fuel/air = better burn. Nothing is black and white though, there's always a gray area, like everything in life, lol. Too much of a good thing will bite you in the ass overall.

with no back pressure (which is impossible unless you have no exhaust at all) you can't have exhaust scavenging.

Here:

When an engine starts its exhaust stroke, the piston moves up the cylinder bore, decreasing the total chamber volume. With the exhaust valve opens, the high pressure exhaust gas escapes into the exhaust manifold or header, creating an exhaust pulse comprising three main parts: The high-pressure head is created by the large pressure difference between the exhaust in the combustion chamber and the atmospheric pressure outside of the exhaust system. As the exhaust gases equalize between the combustion chamber and the atmosphere, the difference in pressure decreases and the exhaust velocity decreases. This forms the medium-pressure body component of the exhaust pulse. The remaining exhaust gas forms the low-pressure tail component. This tail component may initially match ambient atmospheric pressure, but the momentum of the high- and medium- pressure components reduces the pressure in the combustion chamber to a lower-than-atmospheric level. This relatively low pressure helps to extract all the combustion products from the cylinder and induct the intake charge during the overlap period when both intake and exhaust valves are partially open. The effect is known as scavenging. Length, cross-sectional area, and shaping of the exhaust ports and pipeworks influences the degree of scavenging effect, and the engine speed range over which scavenging occurs.

The magnitude of the exhaust scavenging effect is a direct function of the velocity of the high and medium pressure components of the exhaust pulse. Performance headers work to increase the exhaust velocity as much as possible. One technique is tuned-length primary tubes. This technique attempts to time the occurrence of each exhaust pulse, to occur one after the other in succession while still in the exhaust system. The lower pressure tail of an exhaust pulse then serves to create a greater pressure difference between the high pressure head of the next exhaust pulse, thus increasing the velocity of that exhaust pulse. In V6 and V8 engines where there is more than one exhaust bank, Y-pipes and X-pipes work on the same principle of using the low pressure component of an exhaust pulse to increase the velocity of the next exhaust pulse.

Great care must be used when selecting the length and diameter of the primary tubes. Tubes that are too large will cause the exhaust gas to expand and slow down, decreasing the scavenging effect. Tubes that are too small will create backpressure against which the engine must work to expel the exhaust gas from the chamber, reducing power and leaving exhaust in the chamber to dilute the incoming intake charge. Since engines produce more exhaust gas at higher speeds, the header(s) are tuned to a particular engine speed range according to the intended application. Typically, wide primary tubes offer the best gains in power and torque at higher engine speeds, while narrow tubes offer the best gains at lower speeds.

Many headers are also resonance tuned, to utilize the low-pressure reflected wave rarefaction pulse which can help scavenging the combustion chamber during valve overlap. This pulse is created in all exhaust systems each time a change in density occurs, such as when exhaust merges into the collector. For clarification, the rarefaction pulse is the technical term for the same process that was described above in the "head, body, tail" description. By tuning the length of the primary tubes, usually by means of resonance tuning, the rarefaction pulse can be timed to coincide with the exact moment valve overlap occurs. Typically, long primary tubes resonate at a lower engine speed than short primary tubes.

 

Do you ever stop? No matter what the case you are the all knowing source of everything. However, multiple people have mentioned all you do is spew bs like a faucet. I can't help read every post as "blah blah blah, blah blah. Blah blah"

Imeanamiriteoramirite?

 

Yawn.

 

Derrick told me you set his sag and it feels like a total different bike. PM me some details dude. I'm thinking about checking into it.

 

Setting sag will definitely improve the ride.

 

anyone have a shock spring compressor tool i can borrow for a day?

 

What details. How to do it, or my contact?
Truth is, I think a fresh round tire and raising it back up made the biggest difference.
The back was extra low, slammed, and flat spotted tire. So he was riding chopper style.
His suspension setting weren't that far off from what I can recall. I don't think we touched preload at all.

 

that is why this thread was created
for BS'n and random shit.
technical shit is welcome as long as they do not consume the thread, or could have been a seperate thread
i did not make the rules... I just created the thread (this is the 2nd or 3rd incarnation i believe?)

-The Cycle Whore

 

Yep.. i can stop...

kinda all started cause you tried to be some know it all dick that didn't know shit

- rep for not owning up to your failure