ENGLISH
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BASIC CARBURATOR SETTING
Type Keihin FCR-MX 37 Keihin FCR-MX 37 Keihin FCR-MX 39 Keihin FCR-MX 41
Carburator-setting number 3700A 3700A 3900A 4122A
Main jet 160 160 178 185
Jet needle OBETP OBEKT OBDVR OBDTP
Idling jet 42 42 42 40
Main air jet 200 200 200 200
Idling air jet 100 100 100 100
Needle position 3. rd from top 3. rd from top 3. rd from top 4. rd from top
Starting jet 85 85 85 85
Mixture control screw open 1,25 0,75 1,25 1
Slide 15 15 15 15
Performance restrictor – Slide stop Slide stop –
Stop pump membrane 858 / 2,15 mm 858 / 2,15 mm 858 / 2,15 mm 858 / 2,15 mm
Hot start device – – – 2,2 mm
250 EXC RACING
Six Days
250 EXC RACING
11 kW
450 EXC RACING
12 kW
BASIC CARBURATOR SETTING
Type Keihin FCR-MX 39 Keihin FCR-MX 39 Keihin FCR-MX 41
Carburator-setting number 3900A 3900B 4125A
Main jet 178 178 185
Jet needle OBDTN OBDVT OBDTP
Idling jet 42 42 42
Main air jet 200 200 200
Idling air jet 100 100 100
Needle position 2. rd from top 3. rd from top 4. rd from top
Starting jet 85 85 85
Mixture control screw open 1,5 1,25 1,5
Slide 15 15 15
Performance restrictor – Slide stop –
Stop pump membrane 858 / 2,15 mm 858 / 2,15 mm 858 / 2,15 mm
Hot start device – – 2,5 mm
525 EXC RACING
Six Days
450 SX RACING
525 EXC RACING
525 MXC RACING
12 kW
525 SX RACING
