|Motorcycle Dynamometer Services
|D&D Cycle Inc.
747 N. Twin Oaks Valley Rd.
San Marcos, CA 92069
|General Big Twin Motorcycle Services
It’s all about the air/fuel ratio.
The right mixture of fuel to air is what gives us proper combustion. When all the fuel is combined with all the free oxygen in the
combustion chamber there is a chemical balance. This air/fuel ratio is called the stoichiometric mixture. For gasoline this is 14.7
to 1. That is 14.7 times the mass of air to fuel. An excessively lean mixture will cause an engine to run too hot. This will cause
damage to the motor and other components. An overly rich mixture is of course a waste of fuel. It becomes evident that air/fuel
ratio measuring is important for tuning an engine. More and more we’re seeing fuel injected bikes with closed loop systems that
can monitor and maintain desired air/fuel ratio. That’s where those oxygen sensors you see in the head pipes come into play.
Carbureted and open loop fuel injected engines cannot make changes to themselves to correct for improper air/fuel mixtures.
How does this air/fuel ratio change? Anything that can affect how your engine breathes will alter the ratio.
Is Dyno-Tuning for you?
Motorcycles from the showroom floor should be good to go. The factory bike is at specs. Most engine performance upgrades will
change the air/fuel ratio requirements for your bike. Aftermarket intake, exhaust systems, and cam changes are the big concerns
for re-tuning. This is where the Dynamometer comes in. While on the Dyno, your bike’s air/fuel ratio is monitored at all throttle
positions and RPM ranges possible. The same combinations you would feel on the road. As mentioned before, carburetors and
open loop fuel injection systems cannot correct themselves. Carbureted engines however, can be re-jetted to achieve desired
results. With our load controlled Dyno we can incrementally and methodically program fuel injected tuners to also achieve the
desired air/fuel mixture. A properly tuned bike will not waste fuel or ruin your engine. Currently, emission related components of
vehicles under the California Air Resources Board jurisdiction can not be tampered with.
D&D Cycle uses a CycleDyn eddy current load dynamometer built by SuperFlow Technologies Group. SuperFlow CycleDyn is
also the official chassis dyno for S&S Cycle. Our machine was built in 1996. It has recently been upgraded and calibrated by
SuperFlow and currently uses the latest version of WinDyn software. We are certified CycleDyn operators.