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Offline eigenvector

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Sticking throttle
« on: July 10, 2015, 04:52:42 PM »
Something I've noticed is that my throttle is sticking open.  It's difficult to rotate the rod at the carburetor, forcing me to close the throttle rather than having it snap closed on it's own.

Obviously it needs to be addressed, but the question - where should I look to address it?  Should I grease the places where the rod enters the carb bodies?  Or is the issue likely something that originates inside the carburetor - like on the needle slides?  This is a PD46a carburetor.

I guess I'm looking for likely places to start.
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Rob
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2018 HD Softail Heritage
1979 CB750K Limited Edition
1977 CB550K
1984 CB700SC Nighthawk
1983 VF750S Sabre

Offline madmtnmotors

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Re: Sticking throttle
« Reply #1 on: July 10, 2015, 05:24:10 PM »
I'm guessing we're talking about the 77 550K in your sig?  ???

If so, is the external return spring in place? Honda part number of the spring is 16036-393-004 and it connects the idle stop bracket to the front stay plate (Honda part number 16119-393-004). It works in conjunction with the coiled return spring on the shaft.
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Offline eigenvector

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Re: Sticking throttle
« Reply #2 on: July 10, 2015, 06:18:07 PM »
The spring is there.  Without the spring in place the shaft is difficult to rotate manually, like it's dragging on something.  I don't see any evidence that it's bent although it probably wouldn't take much of a bend or binding to prevent free rotation.

And yes, this is my '77 CB550.
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Rob
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2018 HD Softail Heritage
1979 CB750K Limited Edition
1977 CB550K
1984 CB700SC Nighthawk
1983 VF750S Sabre

Offline mpgholston

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Re: Sticking throttle
« Reply #3 on: July 10, 2015, 06:41:38 PM »
Just to make sure, did you check the locking screw on the throttle handle to make sure it isn't engaged? I'm assuming a 77 has one. Also if the cable is adjusted to far out (at the handle) the cable can bind. Oh, while stuck try rotating the handle bar back and forth and see if it frees up. This happened to me once.
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All Stock and All Spec 1974 CB550.
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Offline RevDoc

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Re: Sticking throttle
« Reply #4 on: July 10, 2015, 07:52:04 PM »
MPG may be steering you in the right direction. I had a problem with the throttle on Angie not dropping down to idle. Changed out the throttle cables and problem solved.
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Offline mrfish2

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Re: Sticking throttle
« Reply #5 on: July 10, 2015, 08:06:29 PM »
If it's sticking there are only so many places to look at. You've already said the spring is there and functioning correctly, so the only other things to check for are sticky slides, sticking throttle cable, or maybe the twist grip is binding up somehow. Just went through all this on my bike and it turned out to be a crappy aftermarket pull cable.
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Offline eigenvector

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Re: Sticking throttle
« Reply #6 on: July 10, 2015, 09:17:25 PM »
Alright, I'll quit jerking around then and start with the cables - bind it then see if turning the head will jar it loose.

I still suspect it's the slides, but no sense tearing it apart when I can knock out the easy stuff first.  Never actually thought of looking at the cables - which is probably why I had to ask.
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Rob
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2018 HD Softail Heritage
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1977 CB550K
1984 CB700SC Nighthawk
1983 VF750S Sabre

Offline jayowen

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Re: Sticking throttle
« Reply #7 on: July 10, 2015, 09:22:29 PM »
i had a sticky throttle and it ended up being the throttle tube that was super dirty underneath. i just bought a new one as it was cheap and boooom normal throttle.
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Offline flybox1

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Re: Sticking throttle
« Reply #8 on: July 10, 2015, 10:08:02 PM »
Throttle grip edge too close to control and rubbing? Gunk under your throttle tube?
Gunked push / pull cables?
Spray carb cleaner on all the moving parts at the throttle bell.  Carefully lube the moving parts.
Choke butterflies centered in Carb throats?
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Offline eigenvector

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Re: Sticking throttle
« Reply #9 on: July 10, 2015, 11:05:48 PM »
Assuming it doesn't rain tomorrow, I'll take a real close look and report back, might be an "all of the above" situation.
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Rob
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1977 CB550K
1984 CB700SC Nighthawk
1983 VF750S Sabre

Offline eigenvector

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Re: Sticking throttle
« Reply #10 on: July 11, 2015, 08:28:09 AM »
Well, I suspect it is an "all the above" situation, however in this instance it looks like the cables are sticky.  Didn't see that coming.  I'll need to pick up a cable lube - since I don't have one.

I did release the screws that hold the slides firm on the rod and the #3 was a bit off-center.  Loosening them released a bit of pre-load in the rod - so I have that anyway.  But sticky cables it is.
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Rob
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1979 CB750K Limited Edition
1977 CB550K
1984 CB700SC Nighthawk
1983 VF750S Sabre

Offline mpgholston

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Re: Sticking throttle
« Reply #11 on: July 11, 2015, 08:50:53 AM »
Hey, doesn't sound too bad.
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All Stock and All Spec 1974 CB550.
In my book, you either screw a guy out of tires OR upload pictures of yourself playing with your crank on the web.  Performing both will render absolutely horrible results. #brimmer.

Offline eigenvector

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Re: Sticking throttle
« Reply #12 on: July 11, 2015, 09:02:55 AM »
No it isn't, although sticky cables sure makes my ride a bit harrowing. :-[
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Rob
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2018 HD Softail Heritage
1979 CB750K Limited Edition
1977 CB550K
1984 CB700SC Nighthawk
1983 VF750S Sabre

Offline eigenvector

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Re: Sticking throttle
« Reply #13 on: July 11, 2015, 10:41:44 AM »
Some pretty nasty stuff came out of those cables, so even if ultimately it doesn't solve my problems 100% - it still needed to be done.
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Rob
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2018 HD Softail Heritage
1979 CB750K Limited Edition
1977 CB550K
1984 CB700SC Nighthawk
1983 VF750S Sabre

Offline links56

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Re: Sticking throttle
« Reply #14 on: July 11, 2015, 10:44:21 AM »
It's crazy how much gunk can get in a cable sheath over the years.
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Offline eigenvector

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Re: Sticking throttle
« Reply #15 on: July 11, 2015, 12:30:54 PM »
Actually I've reassembled the cables and Flybox had it correct - messed up throttle tube.

The cables were sticky, but ultimately it's the throttle tube that's dragging - I don't even think it's the right throttle tube for the bike since the grip doesn't cover the whole thing.

I have a new throttle tube on order, I'll replace it and be glad to have figured it out.
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Rob
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2018 HD Softail Heritage
1979 CB750K Limited Edition
1977 CB550K
1984 CB700SC Nighthawk
1983 VF750S Sabre

Offline Stev-o

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Re: Sticking throttle
« Reply #16 on: July 11, 2015, 04:10:45 PM »
You're gonna need new grips too.   BTW - the tube can be trimmed if it is too long for a specific grip.
I love ProGrips, I get them at Cycle Gear or you can get em at Amazon....


http://www.amazon.com/Pro-Grip-Dual-Sport-Grips/dp/B001RTCPEW
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Offline eigenvector

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Re: Sticking throttle
« Reply #17 on: July 11, 2015, 07:27:52 PM »
The grips will be fine, I can get them to slide off with a hose pick and compressed air.

I have stock grips on the bike, I use the pro grips you mentioned on my CB750 - and they are quite nice.
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Rob
--------------------------------
2018 HD Softail Heritage
1979 CB750K Limited Edition
1977 CB550K
1984 CB700SC Nighthawk
1983 VF750S Sabre
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