so you wanna buy a pipe, eh?

there are several things to consider about pipes. the first thing to know is what you want out of the bike. if you want a real screamer, then an expansion chamber is the only way to go. if you want a fat midrange and good highway cruising, perhaps a tuned exhaust is the best choice. but if you don’t know what you want, you won’t be happy when you get something else, right?

that said, you should know that the exhaust is the one of the most important factors in twostroke performance. without getting too geeky about it, the fundamental characteristics of the cylinder are more important to _making_ power, while the exhaust determines how the power is delivered. the neat thing is that a shitty (read:stock) barrel can get a boost from a nice pipe, and a kit barrel will get a HUGE boost. a pipe is a great bolt-on modification…. here’s why.

2T engines rely on the characteristics of the exhaust to determine how much of the burnt gas exits, and also, how much fresh gas gets to stay in the cylinder. now on a 4T engine, the exh.’s main goal is scavenging burnt fuel from the cylinder. but on a 2T, where the transfer ports letting in fresh mix are right across from the exhaust port, too much scavenging will suck unburnt mix right across the top of the piston and into the exhaust before the port closes (and thus, it never gets burned!)

enter the expansion chamber… basically, the first cone of the chamber is really good at scavenging. it’s the converging cone that solves the scavenging probem, tho, because it creates a backpressure wave that crams the gas back into the barrel right before the piston closes the exh. port back up. pretty slick, huh?

but all pipes are not equal. here are some choices:

for p2s

gofast pipe (scootershop, CA):
nice chrome, but really didn’t do anything for my friend cleveland phil’s bike. sounds fantastic, tho.

toyshop pipe the (scooter cafe, CA):
cheap @180 bucks, but really a high-rev-only pipe. nonetheless, you will definitely beat stock bikes easily, even with a stock top end… until you start cruising on the highway with a p200 ridiculously-high stock fourth gear. you lose a lot of midrange and can’t pull hills as easily in 4th gear. i found it to work much better with a stock top end than a rev-happy kit barrel, as the stock top end’s torquier midrange can more easily cope with the tradeoff between midrange and overrev power. one thing that realllllly helps for a kitted bike is a bigger carb. the difference between my phbh30 and my si24/24 was like night and day… higher wheelies, much fatter midrange than i expected. i had this pipe and liked it, for the money. HOWEVER, if you are going to go all out with a kit (and why not?), don’t waste yr money on a pipe that’s best suited to a stock barrel….

pm tuning pm24ev :
nice. quiet, fast, big midrange and nice top-end. i was soundly trounced by a stock bike with a pm when i had my toyshop and a stock barrel. the fight lasted until the end of 2d gear, then he was gone. about $350 from the UK, and you can get it with a carbon can if you like. they sound like no other… crazy tink-tink-tink sound. very racy.

taffspeed mk4 goldline:
about the same as the pm, but “double-wall” stainless construction or something, supposed to be more durable. a little more expensive than the pm, i think. slightly better peak power in the german scootering test, and they liked it best of all. you will pay for the privilege, however.

sip performance exhaust (germany, but on the internet)
$300-350 gets you a pipe verrrry similar in power to the taffy, plus it’s made of stainless steel. you can’t keep yr spare tire, tho — the pipe rides too high. but it’s extra wide to allow you to use a 4×10 tire no problems. vespa motorsport in CA has started selling this pipe now for $345, but i don’t know how that compares to current exchange rates of the deutschmark (after shipping is figured in).

my personal experience with the s.i.p. pipe has been awesome. slapping it on a malossi with a stroker rotary valve crank and 30 phbh dellorto resulted in fun 1-2 shifts complete with flapping handlebars and wildly waving feet (as i waited for the wheelie to end the first time i ran it out) and easily 10 to 15 mph faster than i was getting with the toyshop pipe. it’s just that good.

and now for the tuned exhausts:


these are not real expansion chambers, no matter what anyone tells you. they are noisemakers. nonetheless, the polini/pinasco ones seem to boost power pretty nicely. they’re loud as fuck, considering they have do have baffles (this is what makes them not true expansion chambers. the leovinci’s muffler always falls off, leading it to sound like a chainsaw.

sito plus:
this is a nice pipe for crusing and hanging around town. not loud at all, and it’s got the most torque low down of any of these pipes (great for pulling hills.) pretty cheap if a shop has em ‘on sale.’ most beginners at modifying bikes want torque, not a peaky, revvy motor. this is what they want. (but i predict eventually they’ll ‘see the light’ and go for a better pipe, at which point the sito goes in the trash and y’r out 80 bucks.

zirri has a crazy following among few ppl – but those ppl love them! this pipe looks like a ‘left hand’ expansion chamber similar to the pm, but i believe it has baffles (and that’s why it’s in this category. scooter center koln sells these… try it out!

for smallframes

i only know three main (true) expansion chambers in this category.


the pm40ev is a trick-ass pipe from pm tuning in england that snakes its way up through the bodywork, with the stinger coming out on the battery side right under the edge of the cowl/door. they claim pwr gains on the order of 5 horse! in my personal experience (on a malossi kitted 135 prim racer), that’s believable.

simonini down and forward:

the simonini down and forward has a trick carbon end can (tho this is an option chez pm) and fits under a primmy… but it looks a little weird. s.i.p. is selling em for 289 DM, which is pretty good the last time i checked.

zirri silent:
this pipe is pretty well-liked in germany and costs exactly the same amount from s.i.p. as the simonini. if i had to choose, i dunno which i’d pick — but you have to factor in the absurd word of mouth and “i’d rather fight than switch” zirri following…. seems like a good choice.

and the tuned exhausts are….
stock Et3 exhaust and the leovinci

the ET3 exhaust is a part that piaggio made for its later primmies with electronic ignition. it looks a little like an ss90 pipe and adds a little over the stock exhaust. frankly, it’s difficult to imagine a pipe that wouldn’t.

finally, the leovinci is a cost-effective remedy. considering the sito plus is difficult to find (only from germany) in this category, and the damn things only cost about $50, it’s worth a shot. they seem to actually do ok, especially when i raced rob caple’s primmy w/ polini kit! of course it’s a whole new ballgame now that he has that pm….