tuned pipe question (SBP)

mechanickid · #1 09-09-2009, 12:49 PM

does the tuned exhaust pipe sold by sick bike parts improve performance more than taking all the baffling out of stock pipe would? (which is a straight shot out)
in my experience with these motors no back pressure is better than some.

foureasy · #2 09-09-2009, 01:33 PM

back pressure has very little to do with these motors

Ghost0 · #3 09-09-2009, 02:15 PM

If back pressure meant nothing on a 2 stroke then all the tuned pipes would have the same diameter stinger pipe as the header pipe. I have yet to see a properly designed expansion chamber where this is the case.

mechanickid,
Read the reviews on our site about the pipe and it should let you know what you can expect as far as performance improvements.

foureasy · #4 09-09-2009, 03:23 PM

got one right here. with as much porting as i did to this motor and a stinger that was .60 of the inlet pipe, you could not even get to the powerband unless you were going downhill, and when you did it felt like the motor was gonna zoom off the frame and down the road. i tried a few different combinations with the stinger and found that the outlet size being the same as the inlet gave this motor such a broad powerband and made the bike so rideable, that there is no other option for me. every inch of stinger that i cut off made it better and better. maybe it only works on high rpm motors, cause thats all i've tried it on. maybe you should try it before you bash it, cause 39-40mph with a 36t sprocket and a 24.5" tire seems pretty good to me.

Ghost0 · #5 09-09-2009, 04:08 PM

Not bashing anyone, simply stating the facts as backed up by 30 years of 2 stroke tuning experience as well as any tuned pipe design literature or design software you care to read or use. Header length and expansion chamber shape will effect the required stinger size and apparently your design to work correctly needs a larger stinger size. Nothing wrong with that but for an optimum design to provide improved power through a large rpm range typically requires a little back pressure. They are all a bit of a compromise. The trick, in my opinion, is to get one that provides increased power over a wide rpm range rather than peak power in one small rpm range.

foureasy · #6 09-09-2009, 06:40 PM

Quote:

The trick, in my opinion, is to get one that provides increased power over a wide rpm range rather than peak power in one small rpm range.

that is exactly what i have done with the aforementioned pipe

xlite · #7 09-09-2009, 10:18 PM

Quote:

Originally Posted by foureasy

back pressure has very little to do with these motors

hahahahahahahahahahahahahaha...

mechanickid · #8 09-09-2009, 10:46 PM

okay so back pressure DOES matter, otherwise these would be no better than just taking exhaust off all together.

ghost0, i only found one pipe review one the site, are there more?

also, does anyone know HOW an pipe changes the powerband? as in the term "up on the pipe"

Ghost0 · #9 09-09-2009, 11:03 PM

If you click on the little arrow above the review section on the right side of our home page it will take you to all the reviews.

All tuned pipes increase horse power over some rpm range, some do it over a small rpm range that can be at low, middle or high rpm. I think ours does a nice job of increasing the power band over a larger rpm range than most.

mechanickid · #10 09-09-2009, 11:04 PM

ok so dont worry about explaining how the pipe effects the powerband, i found a great article on tuning.
Exhaust and Intake Tuning