Author Topic: stalling at the stop sign...or end of ride.  (Read 1620 times)

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Offline setdog

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stalling at the stop sign...or end of ride.
« on: May 05, 2013, 08:53:11 AM »
75 cb750

I think this is common problem.  I've had this bike about a month and while it keeps
Getting better issues remain.   

Today this is my problem.  Took bike out for a brief loop around the block, got to the stop sign
Dropped into first, as I came to a complete stop I pulled in the clutch and the bike stalled.

Waited a moment, set into neutral, restarted with a little throttle, vroom vroom, pop into first
And away I go. 

Get to my driveway, shift down to first, as I approach the bottom, still in first, pull in the clutch,
Stalls again. 

Repeated the route a second time and got exactly same results.

Thought I would ask for some opinions before putting on my blindfold and mittens, and start hammering away at stuff.

Idle jet, clogged passage?
Float height?
Vacuum leak?
Throttle stop? - don't think this is it.
Air fuel mix? - don't think this is it.
Carb sync? - doubtful.
Dirty plugs? I don't think so. But Im so not an expert.
She idles pretty nicely from a cold start around 1k. +/- 100 rpms. Runs pretty nicely too.
But obviously I don't want to be starting up at every intersection.
« Last Edit: May 05, 2013, 09:01:27 AM by setdog »
My toolbox consists mainly of hammers.

76 CB 200T. (sold)
75 CB 750 K5. (sold)
74 CB 750 K4. (current rider)
73 CB 750 K3. (build)

https://www.youtube.com/user/setdog100

bollingball

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Re: stalling at the stop sign...or end of ride.
« Reply #1 on: May 05, 2013, 09:38:06 AM »
So are you saying as long as you have the clutch pulled in it will idle fine and as soon as you let the leaver out it shuts down? Does it lurch forward any at all?

Ken

Offline setdog

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Re: stalling at the stop sign...or end of ride.
« Reply #2 on: May 05, 2013, 09:53:48 AM »
So are you saying as long as you have the clutch pulled in it will idle fine and as soon as you let the leaver out it shuts down? Does it lurch forward any at all?

Ken

When i approach a stop, slow down, pull the clutch in, it stalls.
My toolbox consists mainly of hammers.

76 CB 200T. (sold)
75 CB 750 K5. (sold)
74 CB 750 K4. (current rider)
73 CB 750 K3. (build)

https://www.youtube.com/user/setdog100

Offline HondanutRider

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Re: stalling at the stop sign...or end of ride.
« Reply #3 on: May 05, 2013, 10:01:18 AM »
I think this fairly common.  One thing I've noticed is that the throttle linkage has a rest position at idle and then you can over-rotate (i.e. further "off") from this "rest position.  This will close the throttles even more and reduce the idle to an even lower position.  This causes the motor to often stall.  Try not to unwind the throttle too much, or perhaps there is a stop on the linkage that can be adjusted to prevent over-rotation below idle.

Offline setdog

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Re: stalling at the stop sign...or end of ride.
« Reply #4 on: May 05, 2013, 10:20:45 AM »
I think this fairly common.  One thing I've noticed is that the throttle linkage has a rest position at idle and then you can over-rotate (i.e. further "off") from this "rest position.  This will close the throttles even more and reduce the idle to an even lower position.  This causes the motor to often stall.  Try not to unwind the throttle too much, or perhaps there is a stop on the linkage that can be adjusted to prevent over-rotation below idle.

Is this what the manual refers to as overcross? This might very well be where the problem is coming from. Because this does seem like that I've observed.  And I haven't invested enough time
Figuring out this aspect of throttle adjustment.  Mainly because its a pain in the arse...tank on, tank off, tank on, tank off, tank on,... I just wanna ride!!

PS.  I'm a garage hack...I do things the only way I know how...and I really don't know how to do much.
« Last Edit: May 05, 2013, 10:26:40 AM by setdog »
My toolbox consists mainly of hammers.

76 CB 200T. (sold)
75 CB 750 K5. (sold)
74 CB 750 K4. (current rider)
73 CB 750 K3. (build)

https://www.youtube.com/user/setdog100

Offline bjbuchanan

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Re: stalling at the stop sign...or end of ride.
« Reply #5 on: May 05, 2013, 02:39:33 PM »
It could be as simple as you having not set your main idle knob on a warm engine. Lotsa guys used to newer stuff or vacuum style chokes don't like the idea they have to tend to a cold bike, they would rather spend that time gearing up. Such is life, see if that is your problem. A cold engine, choked at 1200 rpm will be wayyy too low warm with the choke off
The dirty girl-1976 cb750k, Ebay 836, Tracy bodykit
Round top carbs w/ 38 pilots, middle needle position, airscrew 7/8ths out, 122 main jet
Stock airbox w/ drop in K&N, Hooker 4-1

Don't trust me alone with a claw hammer and some pliers

Offline setdog

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Re: stalling at the stop sign...or end of ride.
« Reply #6 on: May 05, 2013, 05:53:56 PM »
Interesting...I will look into that, it is quite possible since I hardly put miles on it, I may never really
Achieve a good warming when I'm doing these adjustments.
My toolbox consists mainly of hammers.

76 CB 200T. (sold)
75 CB 750 K5. (sold)
74 CB 750 K4. (current rider)
73 CB 750 K3. (build)

https://www.youtube.com/user/setdog100

Offline seanbarney41

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Re: stalling at the stop sign...or end of ride.
« Reply #7 on: May 05, 2013, 07:21:48 PM »
+1, it really takes a surprisingly long time to get these bikes fully warmed up, also, 1000 rpm is pretty low idle speed...try 12-1500 rpm
If it works good, it looks good...

Offline bjbuchanan

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Re: stalling at the stop sign...or end of ride.
« Reply #8 on: May 05, 2013, 07:30:14 PM »
+1, it really takes a surprisingly long time to get these bikes fully warmed up, also, 1000 rpm is pretty low idle speed...try 12-1500 rpm

True, warm enough to turn the choke off and it doesn't die isn't really warm for these suckers
The dirty girl-1976 cb750k, Ebay 836, Tracy bodykit
Round top carbs w/ 38 pilots, middle needle position, airscrew 7/8ths out, 122 main jet
Stock airbox w/ drop in K&N, Hooker 4-1

Don't trust me alone with a claw hammer and some pliers

Offline flybox1

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Re: stalling at the stop sign...or end of ride.
« Reply #9 on: May 06, 2013, 09:00:41 AM »
my K8 idles really well at 1400.  it takes a good 10 minutes to get it warmed to the point i can take it all the way off the fast idle cam.  after about 30 minutes of riding, i could drop the idle to 1200-1300.
1400-1500 is not too high of an idle.  set it to hold there, and leave it.
'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 greenjeans

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Re: stalling at the stop sign...or end of ride.
« Reply #10 on: May 06, 2013, 10:49:17 AM »
It could be as simple as you having not set your main idle knob on a warm engine. Lotsa guys used to newer stuff or vacuum style chokes don't like the idea they have to tend to a cold bike, they would rather spend that time gearing up. Such is life, see if that is your problem. A cold engine, choked at 1200 rpm will be wayyy too low warm with the choke off

What he said.
Yep, I'm the kid that figured out how to put things back together...eventually.

Offline 750K

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Re: stalling at the stop sign...or end of ride.
« Reply #11 on: May 07, 2013, 12:55:57 AM »
my K8 idles really well at 1400.  it takes a good 10 minutes to get it warmed to the point i can take it all the way off the fast idle cam.  after about 30 minutes of riding, i could drop the idle to 1200-1300.
1400-1500 is not too high of an idle.  set it to hold there, and leave it.
My 77 is the same, it's happiest at idle around 1300.
77 Cb750, 78 Kz1000