Wednesday, February 2, 2011

Yamaha YICS-Good for fuel economy

Have you ever wondered what YICS is? Why is it blazoned into the covers on the engine of your older Yamaha motorcycles? Is it like Wonder Bread? Does it make your bike run farther, jump higher, and outrun the bad guys? Yamaha introduced Yamaha Induction Control System in 1979 as a fuel-saving engine system in 4-stroke motors. As stated in an earlier post, some of the most fuel efficient motorcycles were of the late 70s and 80s. How does it work? The following is a summary of the system from a Yamaha service manual.  "The YICS  consists of 2 separate chambers, each connected, by a hose, to a port on each cylinder just behind the intake valve.  As the piston moves down on the intake stroke, the cylinder fills with a fresh air/fuel charge.  A vacuum is created in the YICS chamber at the same time.  When the intake valve closes, part of the charge is drawn into the YICS.  When the intake valve reopens the mixture in the YICS shoots back out through an angled tube into the cylinder, mixing with and swirling the main intake charge.  The swirling charge is then compressed and ignited, burning more completely and producing more power than that of a conventional engine."
With this in mind, also note that many owners of XJ bikes recommend using high octane fuel, or a good fuel cleaner to keep the YICS tubes from getting clogged. I recommend using a product called FP60 by  On their website the following benefits are claimed for their fuel additive:
  • Antioxidant and solvent properties scavenge water and moisture from the oil and fuel systems
  • Emulsifies carbon and varnish and most other "gunk"
  • Stabilizes the fuel, allowing more efficient burn in the combustion chamber
  • Lowers fuel mixture freezing points
  • Reduces carbon dioxide and NOX emissions up to 30%
  • Leaves a thin, protective coat of oil over vital fuel system parts, including fuel pump, gas tank and fuel injectors.
I've been using FP60 for four years and have had great success with it. Seca turbo fairing, headlight cover, YICS, and a fuel additive....does it all add up to 58 miles per gallon on the Seca 900?  My tests say yes.


  1. Seriously cool. I never understood what that label meant. Thanks!

  2. Maybe this is what wrong with my Virago 500,clogged or something, seems like it get to much fuel and back fires, it idle nice til you give it gas than it craps out like fuel straved.

  3. So how about me being secaman9. Have just gotten my hands on a seca 900rk. Ive always been an eighties metric guy and also wish I had all the wonderful; reliable, fun as hell half liter honeys that make me diehard metric. Hey but can the rk gas petcock be closed for storage? And will you put a turbo fairing on mine like yours if I gave you the parts? And or right now I might part with my museum quality 900seca only for her sake since I'm not a garage owner and she deserves an indoor stall.....