IJSBA received several tech inquiries into the mesh ribbon component on Yamaha Four stroke Watercraft.  The question has been whether the ribbon is part of the spark arrestor system or part of the emission system.  This subject has been thoroughly researched by IJSBA under the supervision of the IJSBA Technical Director.  We have now reached a resolution on the question and find the part, in question, to be part of the flame arrestor system and eligible for removal under Stock Class Rules.

The current Yamaha 1.8L engine  parts catalogs, & Service Guides refer to the flame arrestor as the“ribbon”.  However, this part has previously been referenced as a  “flame arrestor (ribbon)” on page 8 in the 2005 VX110 Service Guide (YMC PN# 90894-64630-73) created by YMC when the VX1100 came out.  The location and function of the ribbon on 1.8L engines is the same as any VX; it is strictly there as a flame arrestor per USCG regulations.

IJSBA further finds that the term “emissions” is also used as a general description on flame arrestors to describe the output of a potential flame or spark when used in flame and spark arrestors.  The description of this part as an “emissions ribbon” refers to the spark/flame sort of emissions rather than having any catalytic function in the changing of pollutant emissions.

The following diagram below supports this finding:

IJSBA further finds that the sensor in this area of the intake system is not an air-flow sensor that measures the oxygen content.   Rather, it is an air pressure sensor.  Therefore, the provisions in the IJSBA Rule Book are satisfied so long as an appropriate flame arrestor is still used on a competition watercraft that has this ribbon removed.  For any questions on this ruling, please contact the IJSBA Technical Director by emailing tech@ijsba.com.

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