2015 US OPEN – ROUND # 1 – DALLAS, TX
BULLETIN US OPEN – DALLAS - 1
IMPLEMENTATION: MAY 6th 2015
This bulletin is necessary to authorize a temporary modification from the current 2015 USRMC Technical
Regulations for the new Electronic Power Valve used with the 125 MAX and 125 MAX DD2 engines. We have
been informed by Rotax that the new Electronic Power Valve may not work properly in some conditions,
especially where tracks are located in high altitude. They identified the problem and the will introduce a
modification kit shortly to solve the possible problem.
Because the modifications kits will not be available for the first round of the US Open, this bulletin will allow
three mounting possibilities for the event.
1. As described in the current 2015 USRMC regulations. If your electronic power valve is mounted
according to the regulation and works perfectly, you may still use this mounting configuration.
2. “Suction mode”: This mode uses the actual parts of the electronic power valve. The only addition
needed is a piece of fuel hose. See image on next page:
a) Connect the pulse hose of the fuel pump to the black plastic Y splitter (1). The opposite
end of the splitter must be connected to the crankcase with hosing as illustrated.
b) The side exit of the Y splitter must be connected to the green check valve (2). The arrow on
green check valve must point towards the Y splitter.
c) The hose from the green check valve must be connected to TOP of the Control Unit (3).
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BULLETIN US Open Round # 1 – DALLAS – 1
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3. “Pressure mode”. This mode uses the actual parts of the electronic power valve minus the existing
internal spring. This mode uses the addition of a spring (Rotax part # 239 940) and a piece of fuel hose.
See image on next page:
a. Connect the pulse hose of the fuel pump to the black plastic Y splitter (1). The opposite end of
the splitter must be connected to the crankcase with hosing as illustrated.
b. The side exit of the Y splitter must be connected to the green check valve (2). The arrow on
green check valve must point towards the Control unit (3).
c. The hose from the green check valve must be connected to the underside (steel nipple) of the
Control unit.(3)
d. In the Electronic power valve, the
compression spring (Rotax part # 638 050)
located under the exhaust valve piston must
be removed. Compression spring (Rotax
part # 239940) must be installed on the
outer side of the exhaust valve piston (same
configuration as the pneumatic power
valve).
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