snippy
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| posted on 31/3/09 at 05:32 PM |
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can I loosen throttle linkage on Webers?
My Set up is a Zetec on twin 45`s. When I blip the throttle it returns quickly enough but seems to stick meaning I`m ticking over too high at around
1200 to 1400rpm. I can then manually push the linkage back to drop it to tickover at 1000 rpm. Can I do anything to loosen the throttle spindles or
even the link arms in between the carbs? The idle adjustment screw is wound right out so thats not affecting things.
Ive just checked my carb balancing and the`yre about spot on at 1000rpm:-
Carb 1 = 4.2 kg/h
Carb 2 = 4.2 kg/h
Carb 3 = 4.2 kg/h
Carb 4 = 3.5 kg/h
How can I adjust Carb 4 to bring it in line with the others?
Cheers,
Nick
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flibble
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| posted on 31/3/09 at 05:42 PM |
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My dellorto`s were the same on my crossflow, I either had the scenario you're talking about or if adjusted it out with the cable I'd end
up with not enough movement for 100% throttle 
In the end I drilled a tiny hole in the linkage arm and connected a spring from it to somewhere suitable to pull it shut properly, seemed the easiest
way - might be the same for you?
Kev
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DIY Si
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| posted on 31/3/09 at 06:11 PM |
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Sounds like you could do with a return spring. It's not unheard of for them to stick open just a bit. As for getting all 4 to flow the same, I
don't know, unless the butterfly plate on number 4 isn't centred fully on the spindle. Which may also be part of the idle problem. IE,
it's not low, but holding the others high due to shutting before the others.
“Let your plans be dark and as impenetratable as night, and when you move, fall like a thunderbolt.”
Sun Tzu, The Art of War
My new blog: http://spritecave.blogspot.co.uk/
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snippy
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| posted on 31/3/09 at 07:12 PM |
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Flibble - I`m using a Magard throttle linkage which has twin throttle cables set up and has 2 springs on it. I did ponder about drilling a small hole
myself in the arm and adding a 3rd spring!
DIY Si - I have also heard that webers are prone to sticking. Not sure if I can alter the butterfly plate, I suppose you must be able to but its a
good point.
Thanks so far guys.
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mark chandler
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| posted on 31/3/09 at 07:24 PM |
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Depending upon the age of the webers later ones have an air bleed screw at the front near the butterfly that you twiddle to even things up at idle.
This saves trying to bend the spindle to achieve an even setting.
These air bleeds are little grub screws with lock nuts if I remember correctly up infront of the fuel bowl.
Best thing to do is remove the linkages and check that the throttle discs are central and one is not landing early (bent spindle) than the other
causing the sticking, it sounds like someone has adjusted the air bleeds to compensate for this.
The air bleeds should be within 3/4 turn of each other if everything else is correct.
Whatever happens you need to start from basics, extra springs may be covering up an issue that should not arise.
Regards Mark
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britishtrident
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| posted on 31/3/09 at 07:46 PM |
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Sounds like the throttle cable could be too tight it also sounds like you might need to balance the bleed screws on one carb.
With the throttle cable adjustment remember you don't need to force the throttles 100% open against the stops as it can damage the carb
spindles and/or break the throttle cable. With the throttle pushed hard to the floor set the throttle cable tension to open the throttles 98 or 99%
open --- this won't cost you any power but will avoid a lot of potential problems.
[Edited on 31/3/09 by britishtrident]
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snippy
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| posted on 31/3/09 at 08:17 PM |
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Mark, I bought my carbs brand new in 2006 so they should be the later ones. On the bottom of each pair of carbs there are 2 small screws with locking
tabs behind. Are these the air bleed screws? I`ve circled them in the attached pic if you can make them out. Alternatively 2nd pic is overhead view of
carbs that may also help.
Trident - My problem exists without the throttle cables even attached so it`s not them.
Nick
 
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snippy
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| posted on 31/3/09 at 08:19 PM |
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2nd pic
 
Rescued attachment IMG_1440.JPG
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mark chandler
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| posted on 31/3/09 at 09:16 PM |
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You need to ensure everything is free starting at the spindles and work back.
Its been a couple of years now but these look like the chaps.
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snippy
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| posted on 1/4/09 at 11:02 AM |
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I`ve adjusted the air bleed screw on the 4th carb and it has balanced it better with the other 3, thanks for that Mark. I still can`t get the revs to
drop right down at tickover, something must be rubbing/catching.
Nick
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MikeRJ
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| posted on 1/4/09 at 05:57 PM |
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If the carbs have ever been run with heavy return springs on the outer ends of the spindles then they can get twisted very easily, which leads to
problems like those you are seeing...
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