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Sticky throttle, no fun! #439636
06/11/12 3:56 am
06/11/12 3:56 am
Joined: Jun 2012
Posts: 4
Gardner,Ma.
Triumphkat Offline OP
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Triumphkat  Offline OP
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Joined: Jun 2012
Posts: 4
Gardner,Ma.
Last riding season was cut short for me an my 77 Bonnie due to a sticky throttle situation. Basically the throttle would stay open reving the bike insanely and making it nearly impossible to bring to a stop at any point. I am looking for solid ideas's on tracking down the problem, I have owned the bike for 12 year's and has been rebuilt within the last 500 miles..finally could spring for the rebuilds! The Amals are like maybe 2 years old, and the throttle cables and junction look new and operate freely. I have yet to inspect the slides for rubbing, but I am suspect. Anywho, look forward to some of the expertise hear chiming in, Best regards, -IP.

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Re: Sticky throttle, no fun! [Re: Triumphkat] #439639
06/11/12 5:23 am
06/11/12 5:23 am
Joined: Sep 2005
Posts: 5,963
NL
G
Ger B Offline
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Ger B  Offline
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NL
Welcome on this board and welcome to the world of AMAL.
Many of us have had these near death experiences. Others will have them. sick

I think we talk about Concentrics.
Slacken the nuts on the flanges that connect the carbs to the head.
When these nuts are to tight, the carburettor housings warp to an oval shape and grab the slides.

Much has been posted about this problem and about Amals in general, during the years.
The board has a search option which can lead you to tons of interesting information.


Ger B

Re: Sticky throttle, no fun! [Re: Triumphkat] #439671
06/11/12 12:14 pm
06/11/12 12:14 pm
Joined: Nov 2005
Posts: 7,258
Back on the mainland!
JubeePrince Online content

Life member
JubeePrince  Online Content

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Joined: Nov 2005
Posts: 7,258
Back on the mainland!
Originally Posted By: Triumphkat
The Amals are like maybe 2 years old, and the throttle cables and junction look new and operate freely.


Did you lubricate the cables and junction box well? Water-proof grease the throttle?

Steve


'77 T140J
"Vintage Bike". What's in your garage?

"The paying customer is always right."

Fitting round pegs into square holes since 1961...
Re: Sticky throttle, no fun! [Re: JubeePrince] #439684
06/11/12 12:54 pm
06/11/12 12:54 pm
Joined: Jun 2012
Posts: 4
Gardner,Ma.
Triumphkat Offline OP
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Triumphkat  Offline OP
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Posts: 4
Gardner,Ma.
I'm definately going to service my cables, I use a cable lubricating tool with spray teflon, that definately could only help, no doubt. I havent lubricated the throttle sleeve itself before, How is it done and exactly what kind of lubricant do you use to do this? Thanks, Iain.

Re: Sticky throttle, no fun! [Re: Triumphkat] #439707
06/11/12 3:29 pm
06/11/12 3:29 pm
Joined: Sep 2007
Posts: 223
Vermont
7
750 Tracker Offline
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750 Tracker  Offline
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Be very careful before you apply grease to the throttle sleeve. It could actually make the sleeve drag on the bars.And as it ages, will begin to harden. Remember how thick grease is. I use Dri-Slide ( a liquid graphite ). You could also use your Teflon spray.

Re: Sticky throttle, no fun! [Re: 750 Tracker] #439725
06/11/12 5:22 pm
06/11/12 5:22 pm
Joined: Jun 2012
Posts: 4
Gardner,Ma.
Triumphkat Offline OP
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Triumphkat  Offline OP
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Gardner,Ma.
I agree, Teflon it is...Thanks.

Re: Sticky throttle, no fun! [Re: Triumphkat] #439726
06/11/12 6:02 pm
06/11/12 6:02 pm
Joined: Jan 2008
Posts: 1,516
Farmington,Connecticut,USA
JBMorris Online content
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JBMorris  Online Content
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Farmington,Connecticut,USA
TK,
Also check at the twist-grip mechanism where the cable runs in.
Mine was dry and sticking bad even after cables were lubed.

.. . used white lithium grease and no prob's since.


1978 Bonneville T140V PX
Re: Sticky throttle, no fun! [Re: Triumphkat] #439732
06/11/12 7:15 pm
06/11/12 7:15 pm
Joined: Nov 2009
Posts: 2,066
Netherlands
Peter R Online content

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Peter R  Online Content

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Posts: 2,066
Netherlands
I agree with Ger, that the most likely cause for your sticking slides is warping of the carburator body's.

Look for the post "straightening AMAL concentrics" by John Healey, he has an interesting method for solving this common problem.


Peter.
1974 Commando 850
1972 Trident T150T
1961 Goldie DBD34
1969 Benelli 250 sport special
Re: Sticky throttle, no fun! [Re: Triumphkat] #439738
06/11/12 7:47 pm
06/11/12 7:47 pm
Joined: Nov 2005
Posts: 7,258
Back on the mainland!
JubeePrince Online content

Life member
JubeePrince  Online Content

Life member
Joined: Nov 2005
Posts: 7,258
Back on the mainland!
Originally Posted By: Triumphkat
I havent lubricated the throttle sleeve itself before, How is it done and exactly what kind of lubricant do you use to do this? Thanks, Iain.


Hi Iain,

See Brien's post. Thats exactly how I did mine.

Steve


'77 T140J
"Vintage Bike". What's in your garage?

"The paying customer is always right."

Fitting round pegs into square holes since 1961...
Re: Sticky throttle, no fun! [Re: JubeePrince] #439748
06/11/12 8:43 pm
06/11/12 8:43 pm
Joined: Nov 2008
Posts: 2,712
Bishop, Calif.
D
desco Online content
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desco  Online Content
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Posts: 2,712
Bishop, Calif.
http://www.gabma.us/page2.htm

You may find some useful info here. Scroll down to tech articles.
There is lots of fun stuff on this page.


1968 T120R
1972 T120RV
Any advice given is without a warranty expressed or implied.
Re: Sticky throttle, no fun! [Re: Triumphkat] #439796
06/12/12 1:55 am
06/12/12 1:55 am
Joined: Jun 2002
Posts: 9,463
Scotland
S
Stuart Online content
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Stuart  Online Content
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Posts: 9,463
Scotland
Hi Iain,

When you open up the twistgrip, what the picture Brien's posted doesn't show is the friction spring and adjusting screw that might be present in the twistgrip mounting (parts 4 and 5 that Brien's marked in yellow in the picture he's posted).

The friction 'spring' is a piece of copper-coloured strip bent into an arc matching the larger diameter of the twistgrip drum (part 9); if it's present, ime it needs very little pressure from the adjusting screw to apply friction to the drum. To ensure that it isn't applying any pressure, I set the adjuster screw and locknut before I assemble parts 4 and 5.

If the friction spring adjuster screw appears to be present, another thing to check is it's the correct one; the screw and locknut drop out if the nut comes loose then they're replaced by any old screw that fits. frown The correct screw has a short length of small diameter without thread - that fits in the hole in the middle of the friction spring.

As I say, I set the adjuster screw and locknut before I assemble parts 4 and 5. I fit the adjuster screw (in part 5) so that just the length without thread is visible inside - to locate the friction spring; obviously, I secure the screw in that position with the locknut.

Btw, because parts 4 and 5 have space for the friction spring, and the cable attachment area on part 9 to rotate, it doesn't matter that 4/5 don't have any grease; nothing of part 9 should contact anywhere on parts 4 or 5 when the former rotates. The only exceptions are:-

. if a 'twistgrip travel limit adjustment screw' (also not shown in Brien's picture) is present; the end of the cable attachment area on part 9 contacts the end of screw if it's present;

. if the screw isn't present, the end of the cable attachment area on part 9 might contact part 4 at the limit of the twistgrip's rotation if the carb. slides don't reach their limit first.

So, during most of the twistgrip's rotation, nothing of part 9 should contact anywhere on parts 4 or 5. However, they're three separate parts so imho it's as well to actually check this during assembly - I rotate the twistgrip every now-and-then as I tighten the two screws (10) that clamp parts 4 and 5 together. When parts 4 and 5 are completely clamped together:-

. if the carb. slides are attached to the other end of the throttle cable, the twistgrip should rotate open easily and snap shut when it's released;

. if the carb. slides aren't attached to the other end of the throttle cable, the twistgrip should rotate easily both ways held only between thumb and forefinger.

Ime, there are also two other places on the twistgrip assembly that can cause drag:-

. because parts 4, 5 and 9 are three separate parts, 4 and 5 allow for a little movement along the handlebar by 9; this can allow the fitted rubber (part 11) to drag against 4 and 5;

. the other end of the rubber 11 can drag on the end of the 'bar;

... if, when you assemble parts 4 and 5 around 9, you're feeling some friction and you're certain nothing on 4/5 is rubbing on 9, try pulling the whole twistgrip a little towards the end of the 'bar.

Finally, I agree with "750 Tracker" about grease (or oil) between the drum and the 'bar; I'd use either the teflon spray, or I've also used the cheap spray-on furniture polish I keep in the garage for fitting and cleaning rubber parts.

Hth.

Regards,

Re: Sticky throttle, no fun! [Re: Stuart] #440267
06/15/12 2:38 am
06/15/12 2:38 am
Joined: Oct 2011
Posts: 228
Ontario, Canada
L
LorenzoI Offline
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LorenzoI  Offline
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L
Joined: Oct 2011
Posts: 228
Ontario, Canada
it seems that I am having the same problem..
the left carb floods after the very first tickle and I have to close the gas tap at mid of his way to stop and start the engine..
then as soon as the engine has started, it revs like crazy until I move the gas cables..


Moderated by  John Healy 


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