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Author Topic: Flat side carb spring  (Read 380 times)

Hurricane

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Flat side carb spring
« on: November 20, 2013, 03:39:25 AM »
I have one of the (Taiwan?) flat side carbs installed on an iron barrel Bullet. I noticed annoying clicks when I rotated the throttle. Just barely felt, but definitely heard. I finally traced the sound to the spring inside the top of the carb body catching on a metal post as it was squeezed. The spring is a long one that seemingly snakes around like a jack-in-the box, so some rings of the spring "catch" as they pull up. Nothing I have done eliminates this clicking.
Why should I worry about that, since I don't hear it while running ?
I don't know, but I still think about it and wonder why this condition exists at all.
Does anyone else experience this?
Otherwise, life is good. Or at least tolerable.

Hurricane

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Re: Flat side carb spring
« Reply #1 on: November 20, 2013, 01:08:41 PM »
Any motorcycle parts shop selling metric parts should have one on the shelf.  Otherwise Bike Bandit or any of those on-line places should have one too.  But you should inspect your slide and throttle cable as well and make sure nothing is binding up in those places.

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Blltrdr

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Re: Flat side carb spring
« Reply #2 on: November 20, 2013, 04:47:22 PM »
What carb are you using? A PWK 30? If so what brand? I'm not sure what the spring would catch on. You are describing it as the spring binding on itself and also catching on a metal post. Have you taken the spring out and compressed it to witness the action? I could see this possibly happening if someone removed the spring and then did something to change the characteristics of it. If you are not the original owner I could see something like this happening. The first sets of PWK's sold by our host's came with a very weak spring that was upgraded to a longer, tighter wound spring with lots of power. Tricky to install the first time. I read of owners of this carb with the HD spring would cut the spring shorter because it was so difficult to install. So thinking along these lines, somebody might want to stretch a weak spring to give it more power. This will ruin a spring and it will never perform correctly again. An example is when you were in school and your spring in your pen would become weak and the ball point would not fully retract or extend. You would take the pen apart and stretch the spring in hopes of repairing the pen. This would last a little while, eventually you would toss the pen.
2003 Classic 500 5 spd
1992 Kawasaki ZG 1200 Voyager XII
1977 Yamaha XS 360-2D (Cafe Project)

D the D

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Re: Flat side carb spring
« Reply #3 on: November 20, 2013, 06:36:14 PM »
I can hear Mikunis doing that when the engine isn't running.  As long as the slide isn't pushed to the side and binding, as in the throttle opens smoothly without jerks, it's not a problem.  At least you know the return spring is strong.  I've seen people cut them off, but if you go too far, it gets too weak to ensure a positive return.  You don't want it stuck open or "up".
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Mike_D

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Re: Flat side carb spring
« Reply #4 on: November 20, 2013, 07:01:52 PM »
I have a TM32 and my spring does the same thing.  It's done that since I installed it and no fiddling will get it to stop clicking.  But it has no effect on throttle motion so I don't worry about it.

cyrusb

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Re: Flat side carb spring
« Reply #5 on: November 20, 2013, 09:27:01 PM »
My pwk 30 has been doing that for 6k miles. It's not clear to me whats doing the fetching, but I have 6k miles on it and no probs. The spring does seem to be longer than it has to be.

Hurricane

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Re: Flat side carb spring
« Reply #6 on: November 25, 2013, 11:41:29 AM »
Yes guys, I think it is annoying when I hear it (because your mind thinks that any noise must be a problem) but I don't think it will lead to premature spring failure or anything like that. In my interpretation, this spring sent with the flat-side carb kit is a long snake-in-a-box affair, and I don't think the spring stands perfectly erect in the chamber.  When the throttle is squeezed, I think the spring pulls up but not exactly straight up, and therefore some rings of the spring "catches" on a boss that the spring fits over in the upper carb top. It happens about 3 times during a full throttle rotation.
I'm not going to mess with anything. As long as it doesn't have "detents" in the throttle, then let it roll.
Thanks for talking about it...
Hurricane

Blltrdr

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Re: Flat side carb spring
« Reply #7 on: November 25, 2013, 04:01:54 PM »
Yes guys, I think it is annoying when I hear it (because your mind thinks that any noise must be a problem) but I don't think it will lead to premature spring failure or anything like that. In my interpretation, this spring sent with the flat-side carb kit is a long snake-in-a-box affair, and I don't think the spring stands perfectly erect in the chamber.  When the throttle is squeezed, I think the spring pulls up but not exactly straight up, and therefore some rings of the spring "catches" on a boss that the spring fits over in the upper carb top. It happens about 3 times during a full throttle rotation.
I'm not going to mess with anything. As long as it doesn't have "detents" in the throttle, then let it roll.
Thanks for talking about it...
Hurricane

Hurricane, if this is the flatslide PWK 30 that our forum host sells you may be able to get a replacement spring for free or maybe a small charge. The flat slide PWK 30 is a carb from JRC Engineering out of Parris, Ca. If you contact them and explain what is happening I would think they would send you out a new spring without a charge. My idle screw on my PWK somehow got bent so I called JRC and they sent my a new one no charge. I have also bought all my maintenance parts for my carb through them also.

Hope this is helps.

Brad
2003 Classic 500 5 spd
1992 Kawasaki ZG 1200 Voyager XII
1977 Yamaha XS 360-2D (Cafe Project)