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Author Topic: High Idle  (Read 1029 times)

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Offline FlyBoy

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  • 1977 CB550K
High Idle
« on: July 27, 2012, 01:29:43 PM »
I just bought a 1977 CB550F and it idles at around 3000 rpm. When i ride and pull the clutch it only falls down to about 2800 at the lowest. I don't know how to fix this. My knowledge is very limited but i can follow directions well. Also my throttle has pretty piss poor response. i have to double grab in every gear 3rd and above. Not sure what to do about that. I'm not afraid to replace old parts with new ones if need be, but i just don't know what to do.Any and all suggestions are greatly appreciated. Thanks Gents!
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Offline brycegp

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    • 1971 CB750 "Mut-N-Chop" Cafe Project
Re: High Idle
« Reply #1 on: July 27, 2012, 01:36:38 PM »
start by turning the idle set screw to the left...this will drop the idle.  see how your bike reacts. 

« Last Edit: July 27, 2012, 01:44:29 PM by brycegp »
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1971 CB750K/F - El Toro
El Toro Build Thread - http://forums.sohc4.net/index.php?topic=73552.0

BrockSamson

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Re: High Idle
« Reply #2 on: July 27, 2012, 01:48:59 PM »
Flyboy the google search at the top left will help you find a solution to your problem.  The search at the top right doesn't work.

I suggest checking the rubbers connecting the carbs to the engine.

Visually inspect them to see if they are on all the way, make sure they all have their clamps and they are tight, check for cracks in the rubber.  Fix any problems you see.  After that take a can of WD-40 and with the bike running spray some towards the boots and see if the idle changes.  If it does you still have an air leak somewhere around that area that you need to fix.

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Offline lucky

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Re: High Idle
« Reply #3 on: July 27, 2012, 01:50:50 PM »
Quote from: FlyBoy on July 27, 2012, 01:29:43 PM
I just bought a 1977 CB550F and it idles at around 3000 rpm. When i ride and pull the clutch it only falls down to about 2800 at the lowest. I don't know how to fix this. My knowledge is very limited but i can follow directions well. Also my throttle has pretty piss poor response. i have to double grab in every gear 3rd and above. Not sure what to do about that. I'm not afraid to replace old parts with new ones if need be, but i just don't know what to do.Any and all suggestions are greatly appreciated. Thanks Gents!

3000 RPM!!! that is not idle!!! That is 1/2 throttle..LOl.
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Offline lucky

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Re: High Idle
« Reply #4 on: July 27, 2012, 01:52:41 PM »
Quote from: brycegp on July 27, 2012, 01:36:38 PM
start by turning the idle set screw to the left...this will drop the idle.  see how your bike reacts.

Why are all of the rubber velocity stacks cut off???
Also all of the idle jets may be clogged up and so the idle may be turned way up for that reason.
« Last Edit: July 27, 2012, 01:55:05 PM by lucky »
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Offline flybox1

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Re: High Idle
« Reply #5 on: July 27, 2012, 01:55:07 PM »
Quote from: lucky on July 27, 2012, 01:50:50 PM

3000 RPM!!! that is not idle!!! That is 1/2 throttle..LOl.
1/3rd throttle for some  ;D  :P
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'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

Past Bikes
1974 550K0 (stock), 1973 CB350F (stock), 1983 Yamaha XS400K (POS)
77/78 cool 2 member #3
"Knowledge without mileage equals bullsh!t" - Henry Rollins

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Offline lucky

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Re: High Idle
« Reply #6 on: July 27, 2012, 01:56:10 PM »
Quote from: flybox1 on July 27, 2012, 01:55:07 PM
Quote from: lucky on July 27, 2012, 01:50:50 PM

3000 RPM!!! that is not idle!!! That is 1/2 throttle..LOl.
1/3rd throttle for some  ;D  :P

Yes....indeed.
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Offline brycegp

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Re: High Idle
« Reply #7 on: July 27, 2012, 02:10:51 PM »
Quote from: lucky on July 27, 2012, 01:52:41 PM
Quote from: brycegp on July 27, 2012, 01:36:38 PM
start by turning the idle set screw to the left...this will drop the idle.  see how your bike reacts.

Why are all of the rubber velocity stacks cut off???
Also all of the idle jets may be clogged up and so the idle may be turned way up for that reason.

that was just a photo I grabbed off Google...not my "rubber velocity stacks".  ;)

regarding the idle jets...I was going to post that too...but didn't wanna scare the guy before he's even check the idle set screw. 

My first assumption was that the PO set the idle high to mask a bad idle issue...so he could sell it.  but again...I didn't wanna scare the guy.  ;)
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1971 CB750K/F - El Toro
El Toro Build Thread - http://forums.sohc4.net/index.php?topic=73552.0
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