If you want to make power on a multi-cylinder engine you have to use a collector system. Whether it's a V-Twin or a V-8 it's the same, and no less an authority than the famed engine builder Smokey Yunick will tell you that. Not using free exhaust energy to help your engine breathe is downright criminal. No matter what the conventional wisdom is, staggered duals on a Harley will not make more power. You simply cannot escape the fact that a properly designed 2-1 will give you more usable torque where you need it, in the 2000 to 4000 rpm range, which means less downshifts and less rpm to get the job done.

A set of short staggered duals at peak rpm can be made to produce good power but they will be dead on their ass until they get there, whereas an engine developed around an LSR 2-1 exhaust can be made to perform from the bottom up with no dips in the torque band! If you don't believe this then why is it always that the top Pro Stock bikes, cars etc. end up running collectors systems? Damn right they work! If you don't think torque between shifts or when you roll the throttle on, then buy those long sewer pipes or some short curly drag pipes you saw on the Discovery Channel.

Check out our new Exhaust Technology Section for information on how all this works.

Typical Comments

14.7 / 13.2 = 1.11

People take their perfectly good Delphi electronics and swap them for a self-tuning "Wide-Band" system. The "Wide Band" manufacturers tell you to run their systems at an air/fuel target of 13.2:1. This simply puts 11% more fuel through the engine, i.e. if you were getting 40 mpg @ 14.7:1, you are now going to get 35.6 mpg. You might as well go get a carburetor. 

The objective of closed loop and narrow band sensors is to get the most efficiency out of your engine by targeting 14.7:1 except in warm-up, sudden transitions, and wide open throttle, as well as hard deceleration and or fuel cut-off. Ratios as lean as 17.0:1 can be run under deceleration and certain no load situations.

FYI maximum constant torque occurs around 13.2:1, whereas sudden transitions can be anywhere from 12.5:1 to 10.0:1 depending on temperature conditions. It isn't simple. EFI isn't Linkerts, Bendix or S&S simplicity. The closest carb you can get to efi fuel control is a CV Carburetor.

Wideband O2  Adaptations 

Systems that typically use Bosch LSU 4.2/4.9 wideband sensors for self-tuning have a built-in problem. First, the "map" has to be correct before any of this self-tuning takes place. Secondly, the real issue is the sensor response time, i.e. the time it takes the sensor to stabilize, and for the ecu to make a corrected output. No matter what they tell your there is a significant delay between the reading and the correction, during which time the engine will be at another rpm/load site . This can be on the order of 980 Ms for the Bosch sensors which is why, in dyno testing, they use step tests for a number of seconds, letting the engine stabilize at specific load/rpm points, before any measurements or changes can be done. Constantly rewriting RAM locations with "corrections" on the fly is never going to be correct.

The OEM narrowband Delphi system actually works twice as fast  500 Ms and the map, as delivered by Harley, is correct. The Delphi ecm has the ability to adjust about 20% in small increments (block learn multipliers) to factor for air cleaners slowly getting dirty etc. It already is self-tuning except at wide open throttle.

Phone Sex and Remote Tuning

In some sort of logical disconnect a few customers call us up wanting us to tune their bike over the phone and then become increasingly indignant when we tell them it just doesn't work that way. Now, we spent the better part of 14 years, starting in 1976 working on carburetors, jetting, needle design, and even designed and marketed a flat slide carb for the Harley market. Thousands of man hours representing about 5 months out of every year were devoted to jetting issues. It got to be a real issue i.e. it was an interesting experience to define what the correct air fuel ratios should be, experimentally figure out how to measure them, and then deal with tuning die cast critters, often modifying them with extra circuits etc. but, in the end, it was temporal and an endless loop that did not exactly pay the bills.

We did learn how to make things run well, not that anyone appreciated it. It was fun to watch people try to beat you when they couldn't. Knowledge. Hard work.

For the last 18 years we've been working on and manufacturing closed loop fuel injections systems for Harley Davidsons and have set numerous Bonneville, El Mirage and Maxton speed records and won drag racing championships with them. We spent over 3000 man hours writing and perfecting Autocal.V6 prediction and analysis software for our RSR Fuel Injection systems. Why did we spend 3000 man hours? Well, we didn't plan on it, and it's a good way to flirt with insanity, but we saw no other option as digital efi requires hundreds of decisions, all of which are intertwined. No more brass jets. Exponential combinations. Changing points, one at a time is sheer insanity. Progress comes with increased complexity.

These days all Harleys are closed loop fuel injected with a single throat throttle body and are speed density Delphi systems, all very complex. It's the same formula we decided on 18 years ago. The only thing we suggest is that you use O2 signals to monitor and tune the system as the sensors are millisecond accurate and must be monitored at the exhaust port where temperatures are high and as far away from the outside oxygen rich air as possible. We suggest you use software, not hardware, to adjust your system using our RSR Air Fuel Ratio Gauges and keep your bike off of the dyno until the lights in these displays tell you your mixture is correct. Engines operate in a very narrow realm of air fuel ratios. If you want to go to the dyno after this...fine.

Just don't call us breathlessly demanding we tune your bike over the phone.

 SuperFlow CycleDyn...Testing a Running Motorcycle

If you are going to use a chassis dyno it has to be a tool and not a toy. At RB Racing we use the SuperFlow CycleDyn as it best emulates the real world. We use it for development and not for publishing "dyno charts". Most of our work is with Pectel SQ6M controllers which have extensive internal datalogging and playback capabilities up to 2000Hz sampling rates. With the SuperFlow we can program specific tests and transient sweeps with our turbocharger systems up 750 hp in inertial mode or 500 hp in Eddy Current controlled accelerations.

For those of you who like Dynojet "Dyno Graphs"..read this article.

Steve Cole (TTS MasterTune) who has spent untold thousands of hours on every dyno imaginable has this to say about CycleDyns:

Steve Cole: "In the development side what I can say is the SuperFlow when setup properly emulates the real world much better. As an example the only way to get a DynoJet to give you HP and TQ is a WOT unloaded run. The SuperFlow allows that plus just about any other combination you like with real torque output. So what does any of it buy you becomes the question. I can tell you that if we tune to a DJ and get the best we can, then repeat on the SuperFlow using real world acceleration rates for the engine being tested the results are very different. Take the final calibrations and run them in both dyno's unloaded and the DJ developed type calibration will show the most HP and TQ in those conditions, on both the SuperFlow in DJ mode and the DJ. Then take the SuperFlow controlled condition calibration and load it in the bike the power will go up when tested in the SuperFlow mode again which can only be done on the SuperFlow. 

Now the hooker, take the bike and put one of the finished calibrations in it and give it to the customer and say go ride it and come back after you've ridden it well, to know how it feels/runs. They come back after an hour or so then load the other calibration and ask them to do the same riding over and come back again. Each and every time we have done this every customer has picked the calibration that was done on the SuperFlow under the controlled acceleration modes! So pick what works for you but there is a difference. Does it take longer, does it end with a measurable difference............. YEP!"

When we have turbo bikes like our Road Glide Turbo it gets a bit interesting to go testing in LA traffic with police, cell phone cameras, and freeway cameras. We still do real world riding with data acquisition as the real world is where you ride.

People want "Dyno Sheets"...see below. We aren't going to test every damn camshaft, compression ratio, piston configuration, cylinder head etc as there is not enough money nor time to do so. However, we do testing for our own race development, R&D, and our personal development platforms.

Dyno Sheets

People call us all the time asking for "Dyno Sheets" and we patiently tell them we do not provide self-serving graphs predicting fantastic horsepower and torque gains. Plenty of customers send us dyno sheets but, as we've been at this a long time, we know the tuning game is too complicated to provide numbers just to sell an exhaust. Tuning is a multi-variable process. 

When the EVO motors came out Jerry Branch published his famous manifesto on tuning 80" EVO motors...In short, unless you bumped the compression the horsepower was not forthcoming. Same these days. In 2014 John O'Keefe of Branch O'Keefe ran an extensive series of tests on OEM Twin Cam cylinder heads to see if he could offer a "less expensive" ported head as everyone with a grinder in his garage was suddenly an expert at cylinder head porting. John found out that any attempt to clean up the ports killed the flow and port velocities dropped. He scrapped that idea and kept his well-proven chamber modification, porting and valve replacement system.

If you are looking for warm cuddly sheets we are clean out of them. We are tuners and you can buy all the trick parts in the world and a guy with a well tuned mild bike with a good power to weight ratio will kick your ass. Real world. Find a good tuner or become one. Look in the mirror.

Torque and Ruby Slippers

People get pissed at us when they ask for "numbers". We always tell them we "don't know" because after nearly 33 years of tuning and racing and designing we have seen too much and done too much to give any placebo answer. In fact it always depends on the bike and the tuner. No two bikes are alike. Maybe your bike was built on a Monday and they left a coke bottle in the gas tank (old Detroit wives's tale)...Some bikes are faster than others. Everyone believes their bike is "faster". It depends on the tuner and, these days, the bikes are more complicated. People change from chain to gear drives. They put on different cylinder heads. They switch cams. They add on tuning twiddle boxes. They tune, or the "shop" tunes. They "dyno" the bike...maybe even somebody rides the bike with instrumentation like our RSR Air Fuel Ratio Gauge.

People call us up then hang up when we tell them we don't know what their "gains" will be. We don't publish self-serving charts. We just take all the experience we have and build the best parts we can. People end up happy who buy the parts because they are well made and are designed to perform. We make different tube diameters and offer a wide range of systems for any particular bike so you will maximize your potential. There is no "One Size Fits All" at RB Racing.

People who don't buy the parts because we won't coddle them with assurances go elsewhere where Aunt Em will tuck them in and tell them what they want to hear.

Our testing has shown that the Harley V-Twin is extremely sensitive to back pressure which is why 2-1's that use small or restrictive collectors don't breathe well, and whyrestrictive baffles shut the motor down. Disc type baffles are good for spark arrestors on dirt bikes but they have no place on a big inch V-Twin. You don't make power by adding restrictions to your exhaust system whether it's a bunch of stainless discs or some damn piece of aluminum billet machined into a Harley butt plug!

Ever wonder why they had to put a hole up the center of the discs? Well, one reason was the discs are so damn restrictive you have to have several pounds of them to get enough flow through their waffle shaped passages. Good mufflers, but they have nothing to do with performance and they sure as hell do not create vacuum as has been claimed.

When you get confused by all the bullshit simply ask the following question.." Do they run them in NASCAR or in Formula One?". Nope, they run straight pipe collector systems without any stupid discs or aluminum butt plugs.It's always funny how when the money is on the line, all the little things like discs, billet caps, anti-reversion flaps, reverse megaphones and other such nonsense somehow don't make the field.