How To Adjust Throttle Free Play And Why - Suzuki GSX-R Motorcycle Forums Gixxer.com
 
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post #1 of 7 (permalink) Old 03-14-2016, 10:37 AM Thread Starter
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How To Adjust Throttle Free Play And Why


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One hallmark of a skilled rider is the ability to precisely deliver the right amount of throttle at the right time. Smooth transitions on and off the throttle play a vital role in keeping the chassis stable in a corner. Since the throttle cables are still, for the majority of bikes, the direct link between your hand and the butterfly valves in the mixers, minimizing slop in the system will pay big dividends.

To check the throttle free play, hold the grip between your fingers and roll it back and forth until you begin to feel the pull of the cable. Pick a spot on the grip and watch it to measure the free play. If you have trouble visualizing the measurement, hold a metric tape measure up to the grip. Most factory manuals will tell you that 2Ė3mm is the correct amount of throttle free play.

Once youíve determined if the free play needs adjustment, loosen the cableís locking nut(s) near the throttle grip. Some bikes will only have one adjuster. For two-adjuster models, loosen the nuts until there is plenty of slack. Next, tighten the deceleration adjuster (the cable that pulls the grip into the throttle-closed position) so that there is no slack when the throttle is held closed. Tighten the deceleration locking nut. Now, adjust the acceleration cableís adjuster until the desired amount of free play is present in the grip and tighten its locking nut. Ensure that there are plenty of threads (at least three) engaged in the adjuster body.

If you canít get the proper amount of free play with the adjusters, youíll need to take up some slack down by the throttle bodies. So, set the adjuster back into the middle of its range before making any changes by the throttle bodyís bell crank. The lower cable adjustment involves loosening the cableís lock nut, making the change to the adjustment nut, tightening the lock nut back in position, and rechecking the throttle free play. Fine-tuning can take place with the adjuster by the grip.
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post #2 of 7 (permalink) Old 03-15-2016, 10:42 AM
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Re: How To Adjust Throttle Free Play And Why

Is that still true for fuel injection?
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post #3 of 7 (permalink) Old 03-15-2016, 11:29 AM
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Re: How To Adjust Throttle Free Play And Why

Is what still true? Whether adjusting throttle cable slack is important for throttle control? I see no reason why it shouldn't be. I far as I can see, the importance of having little slack is that, if you have a lot of it, you'll have to consciously take it up before you start to think about opening the throttle, which is a waste of time at worst or an inconvenient, unnecessary extra step at best. If you don't do that, you'll probably jerk the throttle open as your hand will have gathered some momentum during the initial phase, where its just twisting a freely revolving tube, which will then cause you to open the throttle more than you intended. The fact that during the initial, freewheeling phase, your brain has no feedback with which to calibrate its control over the force applied by your wrist, will probably make things worse.

Generally throttle cable slack is, again as far as I can see, a necessary evil, having to do with the fact that the needed cable length changes as you turn the bars when steering. If you had zero freeplay when the bars are straight, the cable would tighten to the point of pulling the plates open, when in full lock. That's why, instead of shooting for 2-3mm of freeplay or whatever, I just turn the bars to full lock, say left, take up all the slack and then turn the bars to full lock right and make sure the engine doesn't rev up.
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post #4 of 7 (permalink) Old 03-15-2016, 12:15 PM
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Re: How To Adjust Throttle Free Play And Why

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Originally Posted by dpapavas View Post
Is what still true? Whether adjusting throttle cable slack is important for throttle control? I see no reason why it shouldn't be. I far as I can see, the importance of having little slack is that, if you have a lot of it, you'll have to consciously take it up before you start to think about opening the throttle, which is a waste of time at worst or an inconvenient, unnecessary extra step at best. If you don't do that, you'll probably jerk the throttle open as your hand will have gathered some momentum during the initial phase, where its just twisting a freely revolving tube, which will then cause you to open the throttle more than you intended. The fact that during the initial, freewheeling phase, your brain has no feedback with which to calibrate its control over the force applied by your wrist, will probably make things worse.

Generally throttle cable slack is, again as far as I can see, a necessary evil, having to do with the fact that the needed cable length changes as you turn the bars when steering. If you had zero freeplay when the bars are straight, the cable would tighten to the point of pulling the plates open, when in full lock. That's why, instead of shooting for 2-3mm of freeplay or whatever, I just turn the bars to full lock, say left, take up all the slack and then turn the bars to full lock right and make sure the engine doesn't rev up.
I guess I meant do fuel injection bikes use a cable, or do they just have a digital sensor on the throttle. Most cars don't have cables nowadays...
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post #5 of 7 (permalink) Old 03-15-2016, 03:59 PM
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Depends on the bike and year. You'll find both.
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post #6 of 7 (permalink) Old 04-03-2016, 06:37 PM
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Re: How To Adjust Throttle Free Play And Why

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Originally Posted by springfall2008 View Post
I guess I meant do fuel injection bikes use a cable, or do they just have a digital sensor on the throttle. Most cars don't have cables nowadays...

if im correct....this is call..."fly by wire"...which has sensors instead of throttle cable. there were some motogp bikes that were testing with this new function in the early 2003....Aprillia if im correct. after couple of bikes gone on fire with rider on bike....they ended their testing.

not sure if Motogp still testing or using it.
some production bikes came out with it....ducati experimented with some but nothing in concrete.
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post #7 of 7 (permalink) Old 04-03-2016, 11:46 PM
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Re: How To Adjust Throttle Free Play And Why

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Originally Posted by springfall2008 View Post
Is that still true for fuel injection?
Yes. Only downside of the article is the need to swap bars from lock to lock so the cables do not open the bell crank. This way, you can take up more slack until it does.


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Originally Posted by springfall2008 View Post
I guess I meant do fuel injection bikes use a cable, or do they just have a digital sensor on the throttle. Most cars don't have cables nowadays...
As 600 stated, both. From the pre-subthrottle days of hacking Busa's air cleaner door with a tre, to locking the subthrottles open behind the main plate, to running the bell crank outside the throttle body and the fly by wire; opening the only subthrottle in the throttle body.

No more hacking the Busa door open with a tre. The sub can't be wired open because now it's the main throttle.



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