USPKS and Route 66 Sprint Series Tighten Tech on Yamaha Engines

In response to concerns raised by Yamaha competitors and industry engine builders, the USPKS and Route 66 series have moved to eliminate some of the “gray” areas that have been part of the rules packages used by most of the major US race series that allow the Yamaha engine.  These gray areas have been consistently pushed by some competitors, to a point that we believe is detrimental to the sport of kart racing.  An email from Series Tech Director, Rick Jump, was recently sent to the major engine builders involved in the Series.  The relevant text of that letter appears below.


Since the last race of the 2016 season, we have been busy taking a closer look at the Yamaha engine Technical regulations.  Based on what we were seeing last year in our tech inspections, we believe the boundaries have been pushed beyond a reasonable level, by some parties.  Our intent is not to eliminate the Yamaha engine, but to get everyone back to a fair and even playing field.  USPKS and Route 66 Series intends to do what is good for Karting and be a leader in addressing issues, and we feel strongly that this is one issue we need to get in front of.   With the machining technology out there, almost anything is possible. To address this, we will be implementing new rules, and even a new tech tool, for checking the transfer ports.  Many of you saw us testing this in last few races of 2016. This should help turn the rule book back to black and white, and help eliminate the gray areas.

The following changes will be in effect for the 2017 season in both series:

Minimum Blow down – 0.390” (was 0.380)

WA55B Carburetor:

“Tentative” Minimum Throttle Shaft Diameter – 0.182”
“Tentative” Maximum Diameter Throttle Shaft Hole – 0.1875” (Hole cannot be egg shaped)

Other areas of closer scrutiny will be the exhaust and transfer ports. As we all know, the ports are not straight, and when taking measurements, they vary from one end to the other.  If we see ports that have close to the same reading all the way across, more than likely, we will keep cylinder for further investigation.

As always, I will listen to your feedback, but I have talked to a number of you and have received a positive response on this matter.  I appreciate your cooperation with this next step forward.

Rick Jump – Tech Director


For more information on the Series, or to contact the USPKS or Route 66 Series staff, please visit the respective series websites at www.uspks.com or www.route66kartracing.com.  For media information, please contact Tim Koyen at tim@kartlift.com.

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