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Is this a slow action throttle? EVO 300 4T


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This is a standard Beta 4T throttle tube and housing.  The Domino throttle tubes are interchangeable from slow and fast.

The metal housing is the stock throttle housing.  The throttle cable is not connected to the slide on this Mikuni carb as it is a CV carb.

The throttle cable is connected to a cam which in turn is connected to a butterfly valve inside the carb.





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As a side note.  Apart from the fast or slow throttle tubes one can also mess with the cam that controls the butterfly valve. 

Not for the mechanical challenged though.  Just change the throttle tubes i.e. fast or slow.


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My 2013 4T has the standard throttle, which I found to be to fast for my liking. Under a quarter of a turn from nothing to max revs.

I tried a Domino slow action but this was to slow and required more than 180 degrees of the grip to get to full throttle.

The slow action item was not adjustable for cable length like the original, and to get it to work I has to use the other cable hole on the carb.  You'll see what I mean if you look at where the cable attaches to the carb.

As a better compromise I adjusted the stock item.  I trimmed off some of the plastic on the throttle tube.  If you take the throttle grip apart you will see that the throttle cable runs on a raised piece of plastic on the tube.  By reducing the diameter of this, the cable winds more slowly as the grip is turned, and so the throttle speed is reduced. I cut it down to produce a gentle curve for the cable to run on.

I got it to about 110 degrees of turn for full throttle, which suits me.

I now have a spare, used once, Domino slow throttle if you would like it.

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If you want a slower than stock throttle on beta 4t easiest way is buy an amal 80/200 throttle body. No need to swap or adapt cable simply put the nipple on carb end into the other hole on the cam. 5 min job in total and makes noticeable difference

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Thanks for so many suggestions. Actually, I just wanted to be sure that I use the standard or fast throttle (not the slow one). Because I don't like the idea when you have to get used to the behaviour of the slow version and then learn the throttle control again once you are ready for the fast one.

I've checked the color of the plastic throttle and it seems to be grey, so I hope it is not the slow version.IMG_20180119_191144.jpg

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  • 2 months later...
  • 1 month later...

I've got a new Evo 300 4T and want to change the throttle to a slow action. Where in the UK would I get the correct item to do this please? I've read the above advice but seem to be having difficulty finding the parts. Thanks for your help.

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