Bucket Posted October 15, 2005 I fully understand how a 2-stroke pipe works with the ultrasonic waves bouncing in and out of the cylinder....bla....bla...bla. I also understand how different 2-stroke pipe shapes,diameters,straight pipe length affect performance at different rpm ranges. What I don't get is how aftermarket 4-stroke exhausts change/increase power. Has anyone ever disected a silener to see how they differ. Are they longer,shorter? Larger or smaller dia?? Larger or smaller perferations? Do they change the back pressure? Can some one explain this to me please? Thanks Share this post Link to post Share on other sites
yz250ftony Posted October 15, 2005 The Dr D pipe on my 250f is a "step up" design. The farther back the exhaust goes from the engine, the diamater of the pipe increases all the way to the muffler. The pipe is track only. Share this post Link to post Share on other sites
AussieJoe Posted October 16, 2005 Restriction and Back pressure....and ide just like to say that there is NO 4 stroke muffler better than the stock unit. Aftermrket mufflers will take power from one area and increase it somewhere else which is fine for some riders but the majority of us will never need aftermarket silencers.Mufflers and headers are a slightly different story but that means rejetting your bike.....All the money people spend on bolt on performace mods could be spent on maintanace or suspension or lots of fuel to actually practice more to be faster!!!! Share this post Link to post Share on other sites
fest Posted October 16, 2005 on the contrary my dear watson. i have ridden an 05 crf250, with stock pipe, and with pro cirtcuit t-4. the t-4 made it pull harder down low, a more responsive mid, and it pulled terribly hard right to the limiter. the only downside.......... its louder???? but i agree, you could have all the mods in the world, and still not win races. the best way to reduce lap times is to get hours on the bike. Share this post Link to post Share on other sites
AussieJoe Posted October 25, 2005 yeah ok! thats interesting. Was that just the muffler??? Have u ridden a KXF pro circut replica? They look fast! but there slower than the stock KXF! haha. Share this post Link to post Share on other sites
thormx33 Posted October 25, 2005 yeah ok! thats interesting. Was that just the muffler??? Have u ridden a KXF pro circut replica? They look fast! but there slower than the stock KXF! haha. How do you know? Share this post Link to post Share on other sites
AussieJoe Posted October 26, 2005 Ridden both. As has my kawasaki dealer who is a very successfull veteran Motocrosser and he agrees.He said it is slower for the average rider because to go fast you have to ride in the higher RPM which really just wears out your bike and makes alot more noise. On hes 05 KXF250 he actually put a big gun exhaust on between moto's and hated it. He changed it back for the next moto. I know all i talk about is aftermarket exhausts but the money you spend could be spent on a riding school!!....... Share this post Link to post Share on other sites
ea653 Posted October 27, 2005 Aussie I'm with u if your after noise & less power PC is ticket.I have one on my 06 KXF 250 it looks good thats about it.. Mitch Payton laughing all the way to the bank.. Share this post Link to post Share on other sites
AussieJoe Posted October 27, 2005 Haha yeah old mitch is gettn richer and were gettn slower on real loud bikes that are all show and no go!!! Share this post Link to post Share on other sites
