XS650: VM34SC Mikuni   Leave a comment

Yamaha’s Racing Tips Manual, 1974, suggested using VM34SC Mikunis. Round slide. Magnesium bodied. No Power Jet/Accelerator Pump/Beschleunigungspumpe.

Today, TM’s are supposed to provide significant performance improvements. Flat slides and the jet blocks help create a smooth bore effect. Air flows faster and smoother through the TM Series venturi. Higher air flow velocity gives a stronger vacuum at the needle jet needle. Provides more precise metering and better throttle response.

For known geographic and climatic conditions.

However, I do a fair bit of touring. Low to High altitude. For this I actually prefer the original BS series carbs. They automatically adjust themselves for air pressure. Easier to keep tuned.

… VM34SC carb … XS750(650) Racing … adjustments … jet needle 6F9 (#2 clip position)

 

… carb adjustments

 

… carb .. VM34SC … adjustment

 

… VM34SC carb … 3/4-full throttle adj … main jet

 

 

… VM34SC carb … 1/4-3/4 throttle adj … needle jet

 

… VM34SC carb … 1/8 – 1/2 throttle adj … slide adj and cutaway

 

 

… VM34SC carb … 0-1/8 throttle adj … air mixture screw – pilot jet

 

 

… VM34SC carb … idle speed screw

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Posted December 21, 2011 by xscafe in Carb - VM

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