Exhaust Information Page
This page was originally written in 2001 and is oriented towards the RC51 specifically, but the info, dated as it is, still pretty much rings true for all the brands mentioned.
|Due to the
steady influx of e-mails of people asking for my
"opinion" on slip-on exhausts for the RC51 I
have written below some of my thoughts and experiences
over the years based on over 3 decades of extensive carb
& Fi tuning as well as credible reports shared from
other professional tuners.
I would like to start off by saying that the
addition of the PowerCommander (PCIII USB or the new PCV)
is more important than any choice of exhaust. Even if you
are running the stock exhaust cans your bike will benefit
from the Power Commander in terms of improved throttle
response and more linear power delivery. More horsepower
is generally a by-product of those two traits, but is
secondary in my opinion to what the Power Commander is
A little hint I would like to add. If the exhaust you are looking at uses the same size tubing to run from the collector to the exhaust cannister (mid-pipe) then it most likely is not going to be the best choice for performance. Premium exhaust manufacturers (Akrapovich, Harris, Moriwaki, Sato) that truly do the R&D to tune the exhaust flow & reversion waves will use tapered sections of tubing that expand as they move toward the cannister while cheap ass companies simply bend a one size piece of tubing to make it fit the bike...
Finally, no exhaust is 100% perfect. No matter how good or reputable a company is they are going to have a certain amount of failures in the field. Leaking cans, loose rivets or even a mis-shipped part in your kit are all things you can almost expect at some point. The issue then becomes customer service & who takes care of their problems with professional results not just a temporary band-aid to the problem until the next sucker comes along. Personally I feel that if a company is constantly doing development work & trying new things they should be given some leniency if something goes wrong especially in contrast to those companies that never do R&D and have been making exhausts the same way for a decade or more & are still having the same problems today that they had 10 or 20 years ago...
For all you friggin retards that want to hear a .wav file or video of the exhaust sound for comparisons, quit reading now and go somewhere else. Do you really think you can honestly hear an accurate reproduction of how an exhaust sounds through recorded media on the web? I could record the same exhaust from 2 different angles or different distances or with different recorders and you would think it was two completely different exhaust systems. Sound files are a novelty at best & if you are just basing your exhaust purchase on sound alone you wont be interested in the info I have compiled below
There are 4 main topics addressed on
Microns, Moriwaki's & Erions (two sets) on my
personal RC51. All of them are really great cans with
different affects on the engines output. the Erions are
qood quality with a durable finish & without a doubt
one of the best bargains for the money, but their fitment
onto the bike left a little to be desired on two
different installs I have done and performance was bleak
compared to properly tuned exhaust systems. The BEST I
have used are the Sato Exhausts (aka babyface in Japan) which I
used long term and eventually sold the RC51 with. I
continued to use Sato Racing products on all my new bikes
up to the point they decided to stop producing exhausts
and focus their efforts on their CNC parts business. Up
to that point they still continued to dominate the dyno
comparison tests & their build quality was some of
the absolute best in the world. Couple those two very
important qualities with the fact that the US Distributor
also sets the bar by which all other companies are judged
for Customer Service & also gives away free dyno
tuned Powercommander maps for all the products they sell
(about a $300 value for the map) & you just cannot
argue that these were the best exhausts available to us
here in the USA and possibly the world. Unfortunately
they have been discontinued and sold out worldwide for
several years now. Anyway, The Sato's exhausts produced
phenomenal torque numbers with a very unique
configuration of long stepped mid-pipes with short cans
& large cores. Even without a Powercommander the
Sato's produce mid-range gains much higher than any other
exhaust. Of course the whole concept is that it is a
package deal as the Powercommander allows you to fine
tune your fueling to match the exhaust flow & I
firmly believe that every exhaust distributor should
provide free mapping support for the exhaust they sell! I
mean it should simply be an industry standard.
Additional notes on Sato's: they
are were available in 3 mounting configurations in both
Titanium cans and a Carbon Fiber version that is proven
to hold up to the V-twin pulses that caused many other
brands of carbon to fail.
MotoGP style thinline canisters were also available in 2 different lengths, but I gotta tell ya these are just plain obnoxious. Not just on the RC51, but other bikes as well. They are so loud that nobody wants to ride around you and there is nothing cool about them after the first 30 minutes of riding. They attract way too much unwanted attention from cops, draw the ire of your neignbors everytime you fire up your bike and they run hot because of a limited amount of packing inside which also means they need to be repacked much more often than a larger exhaust can that holds more packing material.
On to some other brands, the Leo Vinci's are another pretty good exhaust, but I do not feel they offer the same value for the dollar as the Sato's do as they are fairly expensive & do not deliver the same performance numbers, but are still much better than average. Apparently there have been a lot of issues with distribution and customer service in the US over the last several years as they struggle to retain a proper distributor which brings the future of their products being available into question.
The Microns were the first set of slip-ons I installed
on the RC & are well made, have a long standing
reputation for quality & have unique lateral end cap
mounts that provide secure fastening/easy access, but the
high mount configuration is an abomination. It was
designed purely to fit the bike as an aesthetic
afterthought & performance suffers for it as does
foot room. I believe that Micron has lost sight of their
performance roots & have decided to go after the
poser market spending their resources on polished colored
cans & colored carbon fiber instead of trying to keep
pace with the cutting edge exhaust manufacturers that are
truly getting more power out of their exhausts instead of
just claiming to. The Erions are alot of bang for the buck with
decent power gains & the gloss black powdercoated can
is absolutely gorgeous. I have used Erions on every 900RR
I have ever owned & recommend them regularly for
those riders who are financially challenged. You will be
hard pressed to find a better USA made exhaust, but they
still pale in comparison to the Japanese products. The Moriwaki's build quality is superb, the welds are
meticulously done & power gains are easily seen on
the dyno & felt through the seat, however with the
advent of the new Sato exhausts I have a new favorite.
They produce all the low end power that the Mori's had as
well as a super healthy mid-range torque curve & with
the Fi mappings that we have available there is truly
nothing else like them on the market! It must also be
pointed out that Moriwaki now has a standard mount Slip-on Exhaust that produce power very similar to
the Sato's, not a bad choice if you are not sold on the
looks of the Sato's & still want premium power out of
your exhaust. In addition Sato continues their R&D
long after they have already raised the performance bar
to a new level. They actually redesigned the low-mounts
after first releasing them so that one core is smaller
than the other to better tune the gas flow/back pressure
yielding even more gains over what was already the best
performance increase on the market.
Yoshimura is family
related to Moriwaki so it is no surprise that the dyno
charts are very similar in the fact that both Yoshimura
& Moriwaki produce horsepower in the low &
midrange where the RC51 needed the power the most.
Yoshimura also has a reasonably priced full system
available. This another one where bang for the buck is a
very substantial value. Yoshimura also offers several of
their models with street baffles for a much quieter
exhaust tone. Most importantly in this current day and
age when most companies have completely forgotten about
the RC51 Yoshimura is still supplying exhausts for this
bike and they are still a good quality, consistently made
product even if they aren't the best performing exhaust
Hindle products have been pretty much hit & miss in my experience I have bolted up the same model of system to identical bikes & sometimes they fit great & sometimes they don't. I've never really been impressed with any of their power gains, not that they are poor performing they just don't really stand out when compared to the competition & finally they just look cheap without much design effort, kind of like just bend some tubing & slap on a simple sleeve over a core cannister. Now I'm not trying to advocate form over function, but they could certainly use a little creativity or something to use as a selling point since their performance numbers are nominal.
D&D has a good reputation for build quality, their chrome plating is second to none & they can truly withstand crash damage far better than other manufacturers, of course they are also quite heavy. Their carbon fiber isn't as high quality as other brands & fades quickly, in the process it also becomes quite brittle. It seems with all their slip-ons for various models of bikes, performance is increased but only marginally. Decent can, especially for the money, but there are better choices out there.
M4 exhausts on the RC51 are pretty good bang for the buck too, but they aren't anything special & performance gains are just inline with the rest of the low end exhaust systems. I will say though that since this article was originally written in 2001 that M4 has come a very long way towards improving their performance & quality of their currently offered exhausts. They are now in 2014 without a doubt some of the best value for the dollar domestic USA made exhausts on the market and they have also improved the aesthetics of the exhaust to go along with the built quality and performance improvements. I am personally using their products on several of my bikes where I didn't want to spend a couple thousand dollars on an Akra system including my trusty old F4i and my new to me Gen 4 ZX-10R Track Bike.
Although I was not
originally very keen on the idea of Jardine trying to get in the modern sportbike
market, I must say that I am fairly impressed with the
quality of their product. Only recently have I heard any
negative feedback from owners, but the cans I have seen
in person appear to be very well constructed. Jardine
also has both street baffles & race baffles as an
option. More info on their 2-1 systems below
It should be pointed out that while I am not a fan of the Akra products for the RC51 I still firmly believe they are one of if not the premier exhaust manufacturer in the world. Their exhausts are pricey, but are of exceptional build quality and always fit together perfectly. They also routinely make a lot of exhausts for Factory Race Teams at the World level of competition which says a lot considering there are more than one brand of exhaust out there that pay for sponsorship rights to a race team. More on that further down the page...
Pretty much any exhaust that comes out of England or Italy is crap. People are always quick to point out that Termignoni is from Italy and while Termi's are definitely at the top of the price list they are also at the top of the crap list IMO. They have to be the worst value for the dollar there is as their exhausts look like they were slagged together by some kid in highschool shop class, but you don't have to take my word for it the next time you see a Termi exhaust on a bike sitting outside the local Starbucks take a good look at it and you will see the poor welds and slag marks for yourself. For those of you that will say something really stupid like "well Rossi's M1 MotoGP bike used Termi's" let me retort with no it didn't those exhausts were made by a completely different manufacturer and had a Termi badge stuck on them just like the American Honda Factory HRC RC51 racebikes that Hayden & Duhamel ran had Akrapovic exhausts with Jardine badges. When it comes to big corporate sponsorship deals with race teams you cannot trust much of anything you see...
pic solely for the sake of comparison showing a Sato
Racing Exhaust on the left with a Termignoni exhaust on
Now we switch to the Slip-ons versus Full Systems argument
The short of it is with the RC51 (for other bikes keep reading) I think that Slip-ons are more than satisfactory for most applications & I only recommend Full Systems if you intend to do internal engine modifications such as pistons & cams etc...
dynamics are a science all their own & then you
compound that with jetting or Fi mapping as it is coming
to nowadays and you have a lot of variables in the
finished product. There are so many factors involved in
exhaust building: the diameter of the headpipes as well
as the radius of the bends directly affect the flow
characteristics of the motor, but contrary to popular
myth the angle of the bends in an exhaust system aren't
near as critical to affecting the performance in either
direction as the actual length/diameter of the tubing is
or the angles of bifurcation at any collector are. In
addition to that there are pulse shockwaves from the
valves that need to be tuned to make sure that the pulse
lasts long enough to get all the way through the pipe
without kicking back and causing interference with the
gasses that are trying to escape if that happens then
your engine is robbed of horsepower because it has to
work harder to get the gasses expelled from the motor and
pulse kickback can yield results varying from nothing
more than a slight hiccup at a specific rpm to a lull
spot that lasts for several thousand rpms in the range.
I'm no scientific genius by any stretch of the
imagination and I'm sure there are others that can
explain it much more thoroughly than I can, but my simple
& generic explanation will have to do for now.
All Slip-ons are not created equal! Just as the shape & size of the headpipes affect the gas flow on a similar note the diameter of the cans core as well as the length of the can , the length & shape of the mid-pipes & even the material used for packing will alter the pulses within the system. Slip-ons generally add topend horsepower in exchange for losses in the lowend & frequently mid range too. These can usually be ironed out through rejetting (mapping for you Fi guys), but horsepower is always a trade off somewhere. good midrange usually means less lowend & very little improvement in top end while a system or slip-on tuned for topend will typically result in less low & mid range etc... Look at some of the charts for the Moriwaki Slip-ons, like this one for the Moriwaki versus Arrow Slip-ons they are very unique in the respect that they provide a monster gain in the low rev range & another great gain on the top end, but the mid range does suffer some over other brands of Slip-ons which just further proves my point that it's always a trade off.
Full systems: Again, everything about performance is a trade off. For example you can get cams that offers a strong top end, a good top end with a good mid-range or a great mid-range with a mediocre low end and top end etc... What you can't get is a cam design (at least not with a conventional cam phasing) that allows you maximum hp in all three areas (low, mid & high) of the rev range. Full exhausts are the same. Many full exhausts offer a better top end hit of power at the expense of mid-range performance and usually sacrificing low end power altogether usually along with some throttle response too. There is where you have to ask yourself what you really need in your bike? Do you really spend that much time at redline with the throttle pinned to the stop or would you rather prefer more mid-range power on tap where you spend the majority of your ride time etc... After you answer that question then you need to do some research and decide which full system is good for you. Most do offer better peak gains, but there are exceptions to the rule and in some cases a full system can even hurt performance of a stock bike especially if it is a Full-On Race sytem derived from a Factory Superbike team. I've seen full systems taken from Ex-Factory Superbikes of several different model bikes that actually lose hp when installed on a production based bike like you or I can buy from a dealer. You might score some poser points, but won't gain the power in most cases when you install an exhaust tuned for a 200+ hp race motor on your production based streetbike.
Most Full systems however marketed for production streetbikes or even for mildly tuned race motors will yield horsepower gains throughout the entire rev range so even though it might not be as much mid-range performance as a certain well designed slip-on it will most likely still make more power than a stock exhaust etc...
this far I might as well go on with the Exhaust wrap...
Exhaust wrapping your headpipes can alter the gas flow
& even the reversion pulse waves in some cases. It
can be beneficial for many stock exhaust headers when
used with a slip-on as it tends to allow you to run
stronger in the mid-range (after rejetting/mapping). It
keeps the exhaust gasses hotter longer which makes them
easier to expel out the pipes. We all know that the
hotter something is the easier it flows... Problem is it
is extremely difficult to get the jetting/mapping right
after the wrapping mod & carbs specifically are a
real pain in the ass usually requiring needles many times thinner and outside the
typical range of off the shelf jet-kits... Also wrapping a Stainless Steel
headpipe will rapidly deteriorate the pipe & if you
wrap a ceramic coated header expect an ashy result within
a relatively short time frame. So in the event any of you
follow up on this stuff I only suggest wrapping the stock
headpipes due to their heavy construction... The extra
heat generated inside the pipes by the wrap will
eventually destroy the stock headpipes too, but this
takes a very long time and you can usually find stock
headpipes for sale just hanging in someone's garage... NOW
THE KICKER: Although I have experienced gains by doing
this mod on many different bikes with inline motors, I
have not experienced any appreciable gains with it on the
RC51. Now to clarify that statement let say that my first
attempt was without the benefit of a Powercommander to
alter the fueling & there were zero changes
registered on the dyno with the addition of the exhaust
wrap. I had intentions of trying it again later on, but
simply never got around to it. It was effective
at lowering engine bay temps read by an infrared
thermometer. Let me also say that many RC51 owners have
found it very beneficial to wrap the rear headpipe where
it is in close proximity to the rear shock in an effort
to keep the shock cooler from radiated heat & reduce
shock fade. I tried that and noticed no perceivable
difference whatsoever, but your results may differ. On a
related subject let's discuss Jet Hot coatings: I do not
have any actual experience with the jet-hot coating &
the reviews I get from credible people that have had it
done are diverse to say the least. I am relatively sure
it is a worthwhile investment as in theory it should work
great, but for me it's hard to beat a $50 roll of exhaust
wrap combined with some dyno time...
All that being said the biggest problem is that many people that tend to do this kind of work don't take the time to alter the jetting or mapping properly or don't really understand how to properly jet their bike. They they have a cousin that jetted a bike once (followed the instructions, dropped in a jet kit on the Yamaha 4-Wheeler & now they are an expert) & don't actually have a clue to the principles of why you change needle heights or mixture screws etc... Then you get people saying "well I wrapped my exhaust & it doesn't do anything", but I'm sure you catch my drift.
The 2-1 exhaust fad
with the entire premise of this more midrange power with
a 2-1 which keeps popping up on RC51 forums
I have seen many 2-1
systems yield better topend hp & weaken the mid-range
like on the Erion Superhawk & numerous Hawk GT
systems. That's not to say that with enough piping
& tubing you could get just about any result ya want,
but it will most likely be a point of diminishing return
as the overall power output will most likely be
significantly lower (if you were to purposely build an
exhaust just to prove a point)
Several manufacturers tried their hand at replicating the 2-1 exhaust for the RC51, none made a product truly worth mentioning in that regard.
Update 06/05/02: The Erion 2-1 full exhaust on the 02 bike is producing dismal power curves even worse than stock & has several issues with overheating the motor as well as scorching the single cannister.
Update 07/18/02: dyno charts of the Erion 2-1 with a terrible mid-range dip
Jardine has admitted that they are having problems with the mid-range with their 2-1 system & Arrow is being very tight lipped about their 2-1 after having made a big showing of the prototype many months ago which to me is most likely indicative of their failed attempts or at least performance issues stemming from the design.
UPDATE: Jardine has released their 2-1 full system & the performance numbers aren't bad, nothing spectacular, but no major drops in performance either. A few owners have commented that it leaves a flat spot in the mid-range, but overall with a retail price tag of $499 it sounds like a pretty good deal for those that want more performance than stock, less weight (credible reports have it at a whopping 19lbs of weight savings & a real world price of $390) & something fairly unique dyno chart for Jardine 2-1 another dyno chart for Jardine 2-1 supplied by an actual owner (the mid-range dip is pretty severe on this one). There have also been numerous issues of the welded tab breaking off on them as seen here 2-1 Jardine broke
thing I would like to add: I used to frequently get
arguing e-mails sent to me by some upset viewer of this
page stating that his brand X cans are the best he has
ever had yada yada yada... Well until you have personally
owned or experienced a premium exhaust like Moriwaki,
Sato, AKRA or Hamaguchi you simply cannot understand what
a good exhaust is! You may think your $900 exhaust
slip-ons are the best thing since sliced bread because
you paid so much for them or because they are loud (some
people really use that for an arguement) & yes it did
increase your horsepower, but then again you can remove
the mufflers & run an open header & still see an
increase in power... A premium exhaust not only gives you
added performance, but you get high build quality as well
not just one or the other or in some cases neither... All
you have to do is look at the classifieds you see all
kinds of exhaust for sale all the time like Two Brothers
or Microns etc from people that are looking to
"upgrade", but you rarely see Moriwaki, Sato or
Akra exhausts for sale because nobody has a reason to get
rid of them & there is nothing more to
"upgrade" to. (just something to think about).
Feel free to contact me with any specific questions you might have & I will do my best to get you a researched answer. Or if you feel that any information on this page is blatantly wrong please contact me with proof otherwise.
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