Topic: Last 1/2 inch of throttle!!

[Jim Shea]

When you throttle back, there seems to be another half inch or so of resistance still there on the throttle; when at idle if you twist forward harder it seems to only drop the revs a further 100-150 rpm? Is this supposed to be like this? if so, why is it there at all, I would have thought that when you throttle back, that it would automatically go all the way back?

[Bob Wessner]

I would have thought that when you throttle back, that it would automatically go all the way back?

Jim,

I would think it should also. You should look for anything binding along the entire throttle function/linkage and check the grip also to make sure it is not getting hung-up anywhere.

[Jim Shea]

Bob,
Thanks. I could not see any reason for it, everything seems to work well and does not seem to bind. It does seem deliberate, and not something wrong!

[Gordon]

Sounds like your push/pull throttle cable adjustments are a little off. 

[Jim Shea]

So, there definitely should not be any 'extra' resistance when twisting 'in' the throttle?

[Bob Wessner]

When you release the throttle, it should return all the way to idle on its own. I don't have the twin cable throttle as you do, but I actually prefer mine to have the smallest amount of slack in it, that is at idle, I can move the throttle grip a tiny amount without affecting the rpm's.

[Gordon]

So, there definitely should not be any 'extra' resistance when twisting 'in' the throttle?

There definitely should be resistance when attempting to twist the throttle forward if the engine is already at idle.  With the throttle closed and engine idling, there should be very little available movement left. 

[clarkjh]

Jim

This is for a 74 550K

James

[clarkjh]

try that again

[Jim Shea]

James,
Thanks, very helpful.( My manual is on the way from ebay!!)
Does the 74 550 have twin throttle cables?
Jim.

[Bob Wessner]

There definitely should be resistance when attempting to twist the throttle forward if the engine is already at idle.  With the throttle closed and engine idling, there should be very little available movement left. 

Obviously I'm not familiar with the twin cable behaviour. Just curious, why wouldn't it always return all the way to idle on its own all the time?? 

[Bob Wessner]

Never mind (I think  ), having pondered it a little more, I'm guessing it should return to idle when you just release the throttle, but if it doesn't you can force it closed and without the extra rotational allowance there would be no way to force the closure??

[Jim Shea]

Bob,
I think you have come up with a rational answer, that absolutely makes sense.
Cheers,
Jim.

[clarkjh]

Jim

yep, it has the twin cables.  Can be a real B*&^h to get set sometimes.  First time I pulled the carbs and hooked up again the twist was so stiff I could hardly move it.  Work great once I figured I had miss ajusted the cables. 

James

[Jim Shea]

Jim

yep, it has the twin cables. Can be a real B*&^h to get set sometimes. First time I pulled the carbs and hooked up again the twist was so stiff I could hardly move it. Work great once I figured I had miss ajusted the cables.

James

I am relieved that my bike appears to be right, I didn't fancy adjusting the cables.

[Gordon]

If you have extra forward movement available on the throttle grip when the engine is at idle, then the cables are not adjusted properly.  But it's really just a matter of personal preference.  I like to have a good, solid stop on the throttle grip on my bikes, while others might not notice or even care. 

[Jim Shea]

Gordon,
The extra movement is hardly noticable and the revs only drop by approx 100 rpm, so I guess I can leave it alone as I am used to it?
Jim.

[scondon]

This topic is a few days old but thought I'd post what I found while working on my carbs this weekend.

      That extra resistence is designed into the carbs and definitely should be there. At least on the 75-76 twin cable carbs. Not sure why but it does help bring the idle down after running hot.

       The throttle snaps back and hits the idle screw adjuster plate and stops there. There is a second stop for the forward push on the throttle, which allows you to go past where you've set the idle. It is on a concentric base and can be adjusted to minimize/maximize the amount of forward push. The push cable holder hits this stop. There is a slot with a pin through it towards the rear of the carbs that dictates the maximum adjustment, so if your second stop falls out or goes missing then you will still get stopped.

     Tired, hope I explained this well(Insert sleepy face icon here).

[Jonesy]

If I may add to this...

The two cable rails are actually connected to the throttle shaft via a heavy spring. When you twist the grip beyond the throttle stop, you are deflecting this spring, hence the extra effort required.

These might be of help: