Throttle tube with 2 holes for cables? Why

[Redline Junkie]

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I have a few tubes for the throttle with 2 holes for cable ends? What is the story with that, is this a USA setup, my other bikes have 1 hole?

Thanks

[kobra]

Throttle pull and return. I think it's a safety feature added to let you force the throttle closed if the spring return were to fail. Maybe a later model year?

[75RD350rider]

USA models have push pull cable.

[brrrappp]

It is a common design for multi-carbs that have the throttle actuated by linkage VS individual cables. (safety feature)

[Whymee]

Ever wonder why the USA models did not get the same carbs that the rest of the world got? This is the reason.

Due to the pencil pushers in the US government being smarter than the rest of the world concerning safety, the USA models got the push-pull system. Personally I wish they left well enough alone and we would have got the VM twist off top style carbs. Much easier to deal with.

[evan_calgary]

Agree with all above.

To Whymee's point, it is a real pain to adjust these. I put a set on RD200 and wish I had gone for individual cable carbs due to the difficulty in adjusting needles and mains compared to the usual setup.

The tubes can be used as you would with a single cable from what I have seen.

[brrrappp]

Difficult to adjust was part of the scheme with the 84-85 USA RZ350L/ N /NC/ NC2 carbs.

The California Air Resources Board (CARB) and the US EPA tried to make laws that discouraged selling 2-strokes AND discouraged modification to intake/exhaust systems on all motorcycles.
Yamaha linked the carbs together as a way to better control left/right mixture during manufacture so the setup tech wouldn't/couldn't accidentally create smog and dirty up that "pure" Los Angeles environment.
The Push/Pull throttle is definitely a US mandated safety feature. You will find this feature on all the US street-legal bikes including single cylinder, single carb, on-road / off-road bikes.

[JonW]

The JDM RZs also use the sae carbs.