Stiff throttle

maylar · Aug 31, 2013

Are there different springs for the throttle on Amal carbs? The throttle on my 74 is a lot stiffer than my buddy's 72 and we both have stock carb setups. I take care in routing the cables and they're in good shape, but it gets rather tiring on my hand after a while and I'm wondering what I can do to improve that.

PeterJoe · Aug 31, 2013

Like my 1974 Norton Commando, you may also have the quick throttle twistgrip . Your buddy's 1972 Norton probably has the standard throttle twistgrip. The quick twistgrip would definitely require more effort to lift the throttle slides. I don't know of any lighter springs for the Amal carburetor and according to the parts list, all Commandos have the same spring part number.

rvich · Aug 31, 2013

This is good info to have and I have to admit not something I had considered previously. Can you tell by looking at the exterior of the throttle which one it is?

Russ

pete.v · Aug 31, 2013

If your throttle is snapping back with authority, then you are more fortunate than most. You might go to the hardware store and find a slightly weaker spring or try one of these.

PeterJoe · Aug 31, 2013

rvich said:
This is good info to have and I have to admit not something I had considered previously. Can you tell by looking at the exterior of the throttle which one it is?

Russ

Yes, visually you can see the difference. Here are two pictures:

Amal Quicktwist throttle assembly

All of the replacement quicktwist throttle assemblies that I have seen have an extra screw with a jam nut added in the housing as a full throttle stop. This would definitely get in the way if you wanted to use your turn signal switch.

Amal Standard throttle assembly

rvich · Aug 31, 2013

Thanks for the photos!

Adrian1 · Aug 31, 2013

A member known as DoubleDiamond sells weaker springs on britbike.com
£4 a pair.

batrider · Aug 31, 2013

Adrian1 said:
A member known as DoubleDiamond sells weaker springs on britbike.com
£4 a pair.

I hope his liability insurance is paid up.

rx7171 · Sep 1, 2013

I have a problem of tendinitus in my right elbow that makes my hand go numb after ten minutes of keeping my hand up on the throttle grip.
I've tightened up the screw on the throttle that applies enough friction so I can take my hand off the grip for a short while and hang my arm by my side without the throttle snapping shut.
I know if I go down the motor won't drop to idle but I need to rest my arm.
You could try that so you don't need to be keeping twist pressure on the grip all the time.

concours · Sep 1, 2013

A step in the right direction: http://throttlerocker.com/

concours · Sep 1, 2013

So, was the "Quicktwist" standard equipment on the Commando? Or the standard dullard version?

JohnTy · Sep 1, 2013

Hi
I noted only today that on my mk3 it approx. 1/4 of a full turn from closed to fully open with a standard twist grip.
hope this helps.
JohnT

Stiff throttle

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