I just realized that the geniuses that build these bike use the same 2 stroke exhaust. There for it has an expansion pipe which creates a positive pressure wave to push unused fuel that escapes before the upstroke back into the engine causing a higher compression. Therefore this acts as a small supercharger for 2 strokes. However, It is the complete opposite for the 4 stroke. The expansion pipe on the 4 stroke only causes backpressure slowing exhaust flow and slowing the engine. To create more power and allow much better flow for the 4 stroke put on a straight pipe with a muffler. Try to have the pipe the same diameter as the exhaust port for best results.
i am going to try to make myself a custom exhaust.... maybe a side exhaust, i'm really not that sure. i will post pics of the exhaust if/when i make it. i will also post my bike up for reviews and such today. thanks for the advice of the diameters
I just realized that the geniuses that build these bike use the same 2 stroke exhaust. There for it has an expansion pipe which creates a positive pressure wave to push unused fuel that escapes before the upstroke back into the engine causing a higher compression. Therefore this acts as a small supercharger for 2 strokes. However, It is the complete opposite for the 4 stroke. The expansion pipe on the 4 stroke only causes backpressure slowing exhaust flow and slowing the engine. To create more power and allow much better flow for the 4 stroke put on a straight pipe with a muffler. Try to have the pipe the same diameter as the exhaust port for best results.
does the PBU 4stroke pipe create backpressure or would you cansider this a good pipe (x7) oops old thread, but my Q still stands
I like the way the PBUpipe looks...But the expansion chamber seems incorrect for this application. It may be engineered to work in an unconventional way...who knows.
I do know that exhausts have been made for this type of engine for a long time.. BBR, CHM, 2Bros, Pro Circuit ..etc..All make tested tried and true exhausts that will fit this bike with mild mods...
If you are interested pm me. I customize the exhausts to fit your bike.
I will even sponsor someone to do a shoot out between my exhaust and PBU's...any takers???
You will need to contact PBU to see if they would provide their pipe for objective review...
didn't we already have a discussion about this on another thread already? As far as the PBU pipes go, I think its a good one. I've tested the bike with it vs stock and it kicks ***! Not to mention it sounds great too. But I do have to agree...why the expansion chamber on a 4 stroke? But hey it works great IMO.
didn't we already have a discussion about this on another thread already? As far as the PBU pipes go, I think its a good one. I've tested the bike with it vs stock and it kicks ***! Not to mention it sounds great too. But I do have to agree...why the expansion chamber on a 4 stroke? But hey it works great IMO.
dont buy the pbu pipe, i bout this pipe and it gave me very slight low end and killed my top, my girlfriends stock bike is now faster then mine
interesting topic on exhausts because I have a PBU not yet installed for my
X6 4T. Another rider I know installed his and compared to my stocker he had
a bit more pull on the top end then I did.
That pipe is not designed correctly for a 4 stroke...in fact if anyone is interested I am clearing out the last that I have left. 120+ shipping. i bought a few to test under the false pretense that they were US made...if you want a chinese pipe that sounds better than stock then go for it...(i do not recommend that is why you do not see me pushing this pipe)
honestly, I do not like it...it is the same chinese material that they use with the x7 and x2 fat pipes... these are made for mass production ...not performance. the pipe wall thickness is like 1-2mm it is not good construction. All of the big names in mx make pipes that are tried and true and can be moded to fit the 4 stroke bikes... Save the money and buy better pipe, carb and gearing...or do some free pocket porting!
i will admit that i am biased being a retailer; however, facts are facts.
That pipe is not designed correctly for a 4 stroke...in fact if anyone is interested I am clearing out the last that I have left. 120+ shipping. i bought a few to test under the false pretense that they were US made...if you want a chinese pipe that sounds better than stock then go for it...(i do not recommend that is why you do not see me pushing this pipe)
honestly, I do not like it...it is the same chinese material that they use with the x7 and x2 fat pipes... these are made for mass production ...not performance. the pipe wall thickness is like 1-2mm it is not good construction. All of the big names in mx make pipes that are tried and true and can be moded to fit the 4 stroke bikes... Save the money and buy better pipe, carb and gearing...or do some free pocket porting!
i will admit that i am biased being a retailer; however, facts are facts.
Sid @ Genesis Autoworks, inc
916.685.0062 shop
Hey do you carry the stock gasket for the mid-pipe to header?
That pipe is not designed correctly for a 4 stroke...in fact if anyone is interested I am clearing out the last that I have left. 120+ shipping. i bought a few to test under the false pretense that they were US made...if you want a chinese pipe that sounds better than stock then go for it...(i do not recommend that is why you do not see me pushing this pipe)
honestly, I do not like it...it is the same chinese material that they use with the x7 and x2 fat pipes... these are made for mass production ...not performance. the pipe wall thickness is like 1-2mm it is not good construction. All of the big names in mx make pipes that are tried and true and can be moded to fit the 4 stroke bikes... Save the money and buy better pipe, carb and gearing...or do some free pocket porting!
i will admit that i am biased being a retailer; however, facts are facts.
Sid @ Genesis Autoworks, inc
916.685.0062 shop
Sid is absolutely correct, the PBU 4 stroke pipe is not designed properly. There are several sites out there selling it from $130.00 to $200.00. Nobody has actual numbers of any gains in HP or torque other than it feel faster. It definitely looks nicer than stock, but the expansion chamber design is not what a 4 stroke engine wants to breath out of. Check out FMF, Pro Circuit and White Brothers... pipes for the 50cc engine. None of them are design with an expansion chamber. PBU makes some great stuff, but that pipe is not one of them. My Choice is the Pro Circuit T4, but I don't have a dyno so all I can say for now is it sounds real nice, looks great and seams to have more low end torque.
Paul
didn't we already have a discussion about this on another thread already? As far as the PBU pipes go, I think its a good one. I've tested the bike with it vs stock and it kicks ***! Not to mention it sounds great too. But I do have to agree...why the expansion chamber on a 4 stroke? But hey it works great IMO.
You may have seen some increase because the stock $20.00 pipe on the bike is a piece of garbage. So you could have cut the can off of your stock pipe and made the statement that you saw a 5MPH or even 10MPH increase at the top end and I would believe it, but you destroyed your low end torque. The proof is about how a pipe performs is in the number. Any good design can be proven with HP and Torque gains. PBU and all of the PBU resellers can not state any numbers, HP gains, Torque gains or top speed gains. I doubt they ever put it on a bike to test it. Even if they could prove that the 2 stroke design pipe makes more power on the dyno for some strange reason, for $200.00, shouldn't that thing be stainless or at least HTC coated???
Paul
if anyone still has any doubt about the design of this pipe being wrong, just look up xr50 exhaust. it sure is funny how absolutely NO OTHER PIPES have a chamber design like the pbu pipe. the xr50 motor is of course a different motor, but a small 4 stroke is a small 4 stroke.
I also question the design of the pipe, but I was only saying...it was the first pipe on the market that you could get that is a direct bolt on--without having to cut the pipe to make it fit. Yeah I agree that the XR50 pipes are waaaaayyyy better and they also have like 10 years of R&D. The PBU pipe is an easy install and anything was better than the stock anyways.
Of my expansion chamber and have the pipe going straight back to the tip i gained a lotta torque but lost top speed...what can I do to gain top speed i got alot of torque to spare maybe new sprocket?
4 STROKE exhaust should be a pipe of uniform diameter with as few bends in it as possible. Also if you are going to bend the pipe, use a mandral bending machine that does not change the roundness of the exhaust pipe. I think that a good exhaust would be a 1.5" pipe with a 4" muffler. this would releave a lot of the back pressure and allow you to keep your low end.
does the PBU 4stroke pipe create backpressure or would you cansider this a good pipe (x7) oops old thread, but my Q still stands
I have one and to be honest don't notice the differance except for the sound.
Looks good but gain was very minimal so I just adjusted gearing. If you plan to run a pipe also run a aftermarket filter.
not designed for the 4 stroke engine 
