FASTdan
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| posted on 25/5/12 at 10:57 AM |
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Bike Carbs - Throttle Sensitivity or 'Modulation'
Just out of interest those people running bike carbs - do you suffer from a short pedal throw resulting in a rather on/off throttle effect?
I've noticed this on more than one install, even utilising the pedal as best as possible (so cable linked as close to pivot as possible) at low
throttle openings the modulation is not that great. I've also read this from Dave Walker in a magazine article on bike carb tuning. Of course
this isn't a problem when pushing the car hard, but round town 'trying to be subtle' driving is not so easy lol.
Anyway, just wondering if its a common thing, or what people have done to combat it (if anything at all).
NEW danST WEBSITE NOW LIVE! Bike carbs, throttle bodies and more......
http://www.danstengineering.co.uk/
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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DIY Si
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| posted on 25/5/12 at 11:08 AM |
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Whilst not with bike carbs, but a 48 IDA on my mini, I had this issue. The fix I cam up with in the end used an old SU throttle cable plate as they
have a non-linear opening. Made life so much easier.
“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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paublo999
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| posted on 25/5/12 at 11:18 AM |
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I've been doing some research on this since fitting the supercharger.
Have a look at a "throttle cam". Where you add a longer leg to the throttle "wheel" so that the early part of the throttle
pedal movement has less effect.
I will post links to what I have uncovered when i get home.
Paul
My videos http://www.youtube.com/user/ninjabogeyracing
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FASTdan
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| posted on 25/5/12 at 11:24 AM |
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yeah some sort of cam mechanism was where my thoughts were - seems like a lot of OE throttle linkages are a progressive 'profile'.
NEW danST WEBSITE NOW LIVE! Bike carbs, throttle bodies and more......
http://www.danstengineering.co.uk/
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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paublo999
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| posted on 25/5/12 at 11:27 AM |
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http://www.fastgrandad.co.uk/documents/Throttle%20cam%20and%20roller%20boss.pdf
The second half of this document looks like a solution 
I haven't looked at he fabrication options but I think it would benefit every bec? Anyone interested with a laithe or water jet?
My videos http://www.youtube.com/user/ninjabogeyracing
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DIY Si
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| posted on 25/5/12 at 12:45 PM |
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This is the HIF one I've used with good results:
“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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whitestu
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| posted on 25/5/12 at 01:06 PM |
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This is no issue at all on my ZX6 carbs.
Certainly less on/off than some production cars I've driven.
Stu
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David Jenkins
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| posted on 25/5/12 at 01:58 PM |
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I just shortened the top arm of my accelerator pedal a bit, to reduce the throw. I also put a reasonably strong return spring where the bike's
'pull-the-throttle-closed' cable would have gone, to give a decent feel to the pedal (you can see it at the front of the carbs, next to
the nose cone edge).
 
carb snug fit
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jacko
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| posted on 25/5/12 at 02:33 PM |
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No problem at all with my zx9r / e Carbs
All i have had to do is fit a second return spring
Jacko
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paublo999
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| posted on 25/5/12 at 02:36 PM |
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It wasn't a major issue on my standard zzr1400 but with the charger it has become a not of a handful. The first few mm of throttle can have the
wheels spinning
I have changed the cable mount point to have a longer pedal but I would actually like the first 50% of the pedal to be 20% throttle.
My videos http://www.youtube.com/user/ninjabogeyracing
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deezee
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| posted on 25/5/12 at 02:39 PM |
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I have a set of ZX6R carbs on my car, drives fine to be honest. Very good infact.
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kipper
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| posted on 25/5/12 at 03:32 PM |
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bike carbs
I did have a problem when I fitted mine,(ZX9 carbs, Vulcan crossflow)I cured it with a stronger return spring as others have..
Regards Denis.
Where did that go?
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