RSR Air/Fuel Ratio Gauges

 The Mother of all gauges! Not a gauge, but a precision tool that will tell you exactly what your engine is doing in real-time. Gives you instantaneous read-outs of air/fuel ratios from 17:1 to 10.5:1 and indicates maximum power ratios. Four color display is easily read in direct sunlight and automatically dims at night. Waterproof, billet aluminum construction. Your significant other will cheat on you but this gauge will never lie! It won't keep you warm at night, but a perfectly running engine will look and sound the same when you wake up next to it the morning after.

New Dual O2 Meters

For EFi sequential injection our new RSR Dual Air Fuel Gauge displays the fuel mixture in both the front and rear cylinders separately. The gauge is housed in a hard anodized round enclosure in a standard 2" format with a 2.250" bezel, center back mount, with a 5/16" x 18 stainless socket head cap screw. The gauge will show fuel ratios from 17:1 to 12.0:1 (or richer). The gauge is visible in daylight and automatically dims for nighttime operation.

Scale is, left to right, lean to rich: three greens, three yellows, two orange and two red l.e.d.s.

The white arrow indicates the maximum power mixture, the second orange light, which is 13.2:1. Transitory enrichments should not, if the engine is warm (>200F Oil temp), go past the first red light. Readings at the far right side of the scale, the second red light, are simply too rich. Proper closed loop operation will cycle back and forth from green to orange around the center of the display.

It is simply the best way to evaluate the tune of your motorcycle and saves valuable dyno time. Mounted permanently. Waterproof.

Compatible with OEM narrowband sensors. Can be supplied with new high temperature Bosch narrowband sensors. Far right photo shows gauge in dim light conditions at maximum power setting.

Dual or Single Gauge?

Pretty simple. It depends on what you have.

If you are running a carburetor order the single display meter. All RB Racing LSR 2-1 exhausts have had a front O2 port for the last 20 years. You want to monitor the front cylinder as it requires more fuel. The rear cylinder runs a bit warmer as it is shrouded and it needs less fuel...True, whether you believe it or not.

If you are running an 2006 Dyna or any of the later year dual O2 port, sequential injection models, order the dual display meter.

Mounts....Roll Your Own or Buy One

Three degrees of freedom. Supplied with longer bolts for triple clamp or headlight mounting. Stainless bolts. Or get creative and roll your own. Could be as simple as one hole or a flat strap with two holes. If you want one of these they are $24.95. Part Number 06-1024. No, this is not a Gerbil.

Intsallation Instructions for both gauges as well as the 06-1024 bracket can be downloaded in PDF format.

Waterproof, shockproof, Harley-proof and encased in a hard-anodized billet enclosure that will resist salt spray, the RSR gauge is used in all forms of motor sports: auto, motorcycle and marine. Professional engine builders have discovered the RSR Air/Fuel Ratio Gauge is indispensable for engine dynamometer instrumentation.

The gauge is an industry standard 2" format and is unique in it's ability to provide the driver/operator/tuner exact information that is easily understood and remembered in stressful situations. Sitting on a 425hp motorcycle with 24 lb. of boost you have little time to study instruments...Bouncing thru the waves it's impossible to read a numeric digital display...Running flat out at 200 mph plus you just can't take your eyes off the course! The RSR Air/Fuel Ratio Gauge uses 10 ultra-bright LED's in four colors: 3 green, 3 yellow, 2 orange and 2 red. It's very easy to remember last yellow, second orange, first red etc. Designed to be permanently installed on your vehicle it will provide you accurate data to perfect your engines fuel needs as only one light is lit at a time. Extensive testing has proven this to be the optimum combination. In addition the gauge face plate is marked for Stoichiometry as well as peak power Air/Fuel ratios.

What do the strange lights in the sky mean? Are we about to be visited by Scully and Mulder? Get a grip on yourself, we are talking about gauges not tequila sunrises. If the display gets to the 2nd red (far right) your situation is too damn rich. Further detailed information as to exactly what the air/fuel ratios are for each light and what your target points are for full power, acceleration fueling, steady state operation, idle mixture strength, maximum economy etc. are all contained in a eight page manual that comes with the gauge.

Put your bike on the dyno and....

If you surrender your bike to the hands of another they are going to stick a probe up your pipe to see what's going on. Long rubber tubes, pumps and gas analyzers. There's a lot wrong with this. First off, there is the nasty secret of reversion where the pesky 15 psi of outside air rushes back up the pipe to skew the sampling data. Then there is the fact that you have blocked the exhaust flow with your anally fixated device. Thirdly, there is the time delay of the sampling which means you are always "behind", no pun intended. Fourthly, the load on a dyno does not reflect what you see in the real world.

You are better off running the bike in the real world and watching the O2 display which essentially operates in real time. It will reflect your particular riding style and will save you a lot of money compared to those $200.00 to $400.00 dyno sessions. If dyno numbers are your mantra then do all the tuning in the real world with the RSR Air Fuel Gauge...Then put it on the dyno. The dyno operators are usually amazed on how well the bike runs..."What did you do to it?" is the usual response.

Go back to the top of the page. That big red light is a 12V Dc event based warning light. Two of the wires on your RSR Air/Fuel Ratio Gauge activate this light. One wire goes to a 12V Dc switched power source, the other goes to ground. If you hook the ground up to your oil pressure sending unit the light will activate if you lose oil pressure. People use them to indicate all sorts of 12V Dc events such as nitrous activation, rpm shift lights, high gear indicator (Bonneville), electronic water injection activation etc. etc.

The Dual Air Fuel Meter has two red 12V Dc event based lights...We have big plans for these. You may use them for whatever nefarious purposes you have.

Twin Cam Heat Conundrum

The impending beat of the water buffalos hooves approaches. Behold the last of the air cooled dynosaurs, roasting your legs as if the comet of destruction had already hit ground zero with oil temperatures running 265 to 295 deg F. Ouch!

Oil temperatures in the old, old, days were under 200 deg F. In the mid eighties the 80" Evo arrived and temperatures went to 210 deg F. Oil cooler manufacturers scrambled to take your money. If you were stuck in the Hades of an Arizona Summer you might have been smart enough to run 70 weight Kendall oil. These days they tell you to run synthetic or your bacon will burn.

Those tiny little feed and scavenge gears didn't do much of a job pushing oil in any appreciable volume through a crappy little oil cooler so your scooter ran hotter as the years went by and as California pushed the limits of emission standards. "Cold" engines were dirty and needed more nasty hydocarbons to keep them happy. Greasy, slippery lubricants like lead that reduced friction were sent to the aquifer and your liver but taken from your gas tank. More heat.

Along comes the TC88/96/110 etc. One extra cam forward and ten steps back. Tiny, tiny ports that trap heat, lean mixtures at or short of stoichiometry that keep exhaust gases hot. Cylinder heads that have virtually no fins save a few cosmetic slots and emission laws that sniff your fuel lines and your air cleaner cover. Cam timing with little or no overlap and restrictive exhaust systems. It's no wonder a new 96" fuel-injected Twin Cam makes less horsepower than a decade old 96" S&S engine with a carburetor and runs temperatures that scare you to death and push the outer limits of tribology and chemistry.

Catalytic converters that need heat NOW!

Brave new world. Buy an 800 pound $35,000.00 CVO FLHT and then dump another $10,000.00 into the powerplant so you can keep the faint glimmer of Goldwing taillights in your windscreen. The heat you feel is not always power. The answer is complex and is often defined by the cards you are dealt. The heat you feel is not just the result of "lean mixtures". It's more complex than that.

Closed Loop and O2 Sensors

You drive down to the Harley dealer in your late model car or truck. It starts instantly, works perfectly for years, and it has narrowband O2 sensors. You buy your expensive Harley and want to take off the sophisticated Delphi Closed-Loop Narrowband system and put on a completely new system with Wide Band Sensors or, even worse, you want to put on a Power Commander that eliminates the O2 sensors. Is there some logical disconnect here?

You decide you want to tune your efi so it runs at 13.2:1 instead of 14.7:1. There goes 11% of your fuel economy. The fact is your engine will have the most complete burn @ 14.7:1 and that is where it should run for the best economy and drivability, just like the car and truck you went to the dealer in. Programming and strategy for closed loop tuning is not the same as it would be for carburetion.

If you install some device that installs between the factory OEM sensors and the ecu/ecm and sends a phony signal to the ecu the gauges will simply display the phony signal. That's headed back to electric carburetor instead of a sophisticated closed loop system. Remember that vehicle you drove down to the dealer in.

For a discussion of closed loop issues you can look at our RSR Fuel Injection. We addressed these issues way back in 1990.

The RSR Air/Fuel Ratio Gauge becomes your expert witness...there is no more guessing or having two operators with two different opinions. If you see your mixture going dangerously lean you can instantly back off and save your motor. For developmental purposes you need to have quick answers for full power, transient and steady state operating conditions. The RSR Air/Fuel Ratio gauge is the best tool to provide these answers.

We have included a calculator that shows the relationship of various fuels to one another in terms fuel ratios. At a Lambda value of "1" we have stoiciometry or the point at which the most complete combustion takes place. Values of Lambda less than "1" are richer than stoiciometry and Lambda values greater than "1" are leaner than stoichiometry. You can enter a value for any fuel and the calculations will be automatically made for the other fuels as well a calculation of the corresponding lambda value.

If your vehicle already has one Oxygen Sensor all you need is the single display RSR Air/Fuel Ratio Gauge. If you need to install an O-Sensor in your exhaust we have the 18mm x 1.5mm weld-on, machined adapters. The complete kits are available with either one (1) wire, or four (4) wire oxygen sensors. One wire sensors are unheated and must be installed close to the exhaust port. Our Harley Davidson exhaust systems have an O-Sensor port in the front primary tube about 2 inches from the port itself and use one-wire sensors on carburetted systems.

We use four-wire heated sensors on our RSR EFI systems and use the single display O2 meter with the O2 sensor in the front exhaust port. "Heated" simply means it gets up to temperature quicker. Four wire sensors consist of: one signal wire, two heater wires and a ground reference wire. These heated sensors are also necessary if you get too far away from the exhaust port. How far away is too far away? Well, if you put the sensor under the vehicle and not near the engine you need a four-wire sensor. Another way to look at it is if you are more than 18" downstream, or if you have to go a long way to install it in the collector go to the four-wire sensor. If you can put the sensor near the exhaust port you can use a one-wire sensor.

Late model Harley Davidsons with sequential injection require our dual display meters and use the oem narrowband (two wire) sensors. If you throw away your sophisticated Delphi ecu for some aftermarket wideband ecu (LSU4.2 etc.) these gauges won't help you as the voltages are completely different with wideband units.

There will be a test on this at 2 o'clock.