Author Topic: Do you have to use the Choke to start your bike?  (Read 12297 times)

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Offline bjatwood

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Do you have to use the Choke to start your bike?
« on: August 21, 2011, 05:27:57 PM »
I have a stock 750 K3, I have not had to use my choke EVER to get my bike started up and running. I have been thru the carbs and the bike runs awesome. Getting mid 40's for MPG so I know things are running OK. Just wondering what you guys have to do with your bikes choke to get em fired up. Thanks
Brian
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Offline Stev-o

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Re: Do you have to use the Choke to start your bike?
« Reply #1 on: August 21, 2011, 06:12:59 PM »
I have a K4 w/a 836 kit and aftermarket pipes and have to use full choke to start it cold [even when it's 90* out].

Once warmed up, no choke necessary.

'74 "Big Bang" Honda 750K [836].....'76 Honda 550F.....K3 Park Racer!......and a Bomber!............plus plus plus.........

Offline WarwickE36

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Re: Do you have to use the Choke to start your bike?
« Reply #2 on: August 21, 2011, 06:17:38 PM »
stock 550KO No choke to start.  blip throttle a bit and it starts right up every time.
" Why does anyone get offended by what someone does to their own bike? I dont get it. "

You made me think about it after I cheered knowing someone else would like to know what these control freaks are up to.
 Every time any owner strips whatever precious Honda part the horrified purists parts go up in value. That's not the part that bothers them.
 What bothers them is they sat up late at night, their breast full of wonder and estrogen, unable to sleep, dreaming about their lovely darling and all her glory... and next thing you know someone else doesn't share their emotional deluge and their reaction is they must spread their mind museum as far as they possibly can, taking over as much of the real world as possible.

Drink fast, drive slow, but ride it like you stole it

1974 Cb550 with style
2004 SV650s

orange550

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Re: Do you have to use the Choke to start your bike?
« Reply #3 on: August 21, 2011, 06:24:35 PM »
1974 cb550 No choke. I rev it a bit, and usually it stays running. If I give it any choke it stalls.

Offline VTCBike750

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Re: Do you have to use the Choke to start your bike?
« Reply #4 on: August 21, 2011, 06:35:21 PM »
No choke, bike does not like full choke. Definitely have to adjust the idle screw
-Adam

1972 CB750 (current project)
http://forums.sohc4.net/index.php?topic=87951.0

Offline RustyJC

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Re: Do you have to use the Choke to start your bike?
« Reply #5 on: August 21, 2011, 06:36:23 PM »
1971 CB750K1 takes full choke to start cold (regardless of ambient temperature), then the choke must come off immediately.  After it warms up, it never takes any choke, and just a brush of the start button brings it to life.

Rusty
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2007 BMW K1200GT

bollingball

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Re: Do you have to use the Choke to start your bike?
« Reply #6 on: August 21, 2011, 06:37:59 PM »
In the winter below maybe 40 first time in the morning.

Offline TwoTired

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Re: Do you have to use the Choke to start your bike?
« Reply #7 on: August 21, 2011, 06:43:06 PM »
ALWAYS takes choke to start when cold.  Never when warmed up.
All the stock bikes need choke to start when cold if in proper working order.

If you don't need choke to start, no wonder you get lousy fuel mileage.  It's running too rich, possibly to compensate for owner "improvements"?

Cheers,
Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

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Offline Skonnie Boy

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Re: Do you have to use the Choke to start your bike?
« Reply #8 on: August 21, 2011, 06:45:07 PM »
Bike's bored out to 811, no electric starter and always need the choke unless its over 85º.  Usually need a prime-kick before starting too.  I fiddle with the idle knob lots too.  But I can start it reliably even into freezing temps, so who cares.
"Yeah, I'm hip about time. But I just gotta go."

Offline Tews19

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Re: Do you have to use the Choke to start your bike?
« Reply #9 on: August 21, 2011, 06:52:11 PM »
Bike's bored out to 811, no electric starter and always need the choke unless its over 85º.  Usually need a prime-kick before starting too.  I fiddle with the idle knob lots too.  But I can start it reliably even into freezing temps, so who cares.

Skonie, is that you in your avatar?
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Offline BobbyR

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Re: Do you have to use the Choke to start your bike?
« Reply #10 on: August 21, 2011, 06:53:09 PM »
I have a K8 which has a fast idle cam. I use that to warm it up while I put all my gear on. It does need choke to start first time. I could do it by playing with the throttle game, but that is so old school, I would feel like a Harley rider.  After that I just tap the starter. 
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Offline Skonnie Boy

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Re: Do you have to use the Choke to start your bike?
« Reply #11 on: August 21, 2011, 07:13:46 PM »
Bike's bored out to 811, no electric starter and always need the choke unless its over 85º.  Usually need a prime-kick before starting too.  I fiddle with the idle knob lots too.  But I can start it reliably even into freezing temps, so who cares.

Skonie, is that you in your avatar?

Oh yes.  I am the Packer ninja.  Living amidst the reliable disappointment known as "Chicago Bears Football."
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Offline Really?

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Do you have to use the Choke to start your bike?
« Reply #12 on: August 21, 2011, 07:15:58 PM »
K5 must have full choke if it has not been run for a day. Then I turn it down a bit.
I don't have a motorcycle, sold it ('85 Yamaha Venture Royale).  Haven't had a CB750 for over 40 years.

The Wife's Bike - 750K5
The Kid's Bike - 750K3

Offline seanbarney41

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Re: Do you have to use the Choke to start your bike?
« Reply #13 on: August 21, 2011, 08:33:33 PM »
1971 CB750K1 takes full choke to start cold (regardless of ambient temperature), then the choke must come off immediately.  After it warms up, it never takes any choke, and just a brush of the start button brings it to life.

Rusty
+1 exactly, except it's a k2 motor...
If it works good, it looks good...

Offline jawntybull

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Re: Do you have to use the Choke to start your bike?
« Reply #14 on: August 22, 2011, 01:20:37 AM »
When I bought the bike it was set up way too rich (mixture screw and main jet) - blew black smoke on the highway. In that condition it started without choke. Now I've brought it back to the right mixture, it needs choke to start. I think if you can start it cold without choke its set up too rich for when it warms up; when the cylinder is cold the combustion is not as efficient and fuel condenses on the walls, that's why you need choke.

Bandit 1250S, DR650, CB750K

Offline pknopp

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Re: Do you have to use the Choke to start your bike?
« Reply #15 on: August 22, 2011, 06:34:53 AM »
1971 CB750K1 takes full choke to start cold (regardless of ambient temperature), then the choke must come off immediately.  After it warms up, it never takes any choke, and just a brush of the start button brings it to life.

Rusty

 I have the same bike and if it's real nice out sometimes it will start fine without the choke. Generally I do the same. Full choke, start, immediate off. I've only had this bike since spring so I can't comment on cold weather starts.
 
 My Dream always requires the choke. Still just for a few seconds unless it's real cold.

Offline Simpson

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Re: Do you have to use the Choke to start your bike?
« Reply #16 on: August 22, 2011, 07:01:55 AM »
ALWAYS takes choke to start when cold.  Never when warmed up.
All the stock bikes need choke to start when cold if in proper working order.

If you don't need choke to start, no wonder you get lousy fuel mileage.  It's running too rich, possibly to compensate for owner "improvements"?

Cheers,

+1
750 K0
45-50mpg
Need choke unless engine warm, just for a second.

The same applies for all my vintage bikes...
« Last Edit: August 22, 2011, 07:03:56 AM by Simpson »
1970 CB750 K0
1975 CL/CB 360 Mix

Offline Coyote13

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Re: Do you have to use the Choke to start your bike?
« Reply #17 on: August 22, 2011, 07:03:13 AM »
I just turn the idle up a hair (78 750K) until she warms up.  Get it settled back down to ~1100 and don't have to worry about it the rest of the day, unless it's really cool out, which is pretty much never.
'78 CB750K.  Throttle ripper.
'71 CB100.  Grocery getter.
'01 XL883.  Panty dropper. Gone but not forgotten.

Offline bjatwood

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Re: Do you have to use the Choke to start your bike?
« Reply #18 on: August 22, 2011, 07:06:54 AM »
no wonder you get lousy fuel mileage.  It's running too rich, possibly to compensate for owner "improvements"?

Mid 40's is "BAD".... I thought HONDA said that 42.23 MPG is what a early 750 should get milage wise? Did I read that wrong?  :o  And my plugs are a nice light brown color, not Black at all. Maybe I would get better milage if I didn't drive 70 MPH... and I KNOW I need a carb sync, my Buddy has a sync kit that he has promised to come over and do, but he's been too busy with his business to come over and do it.
« Last Edit: August 22, 2011, 07:09:32 AM by bjatwood »
Brian
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Offline dna_level_c7

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Re: Do you have to use the Choke to start your bike?
« Reply #19 on: August 22, 2011, 07:24:12 AM »
I always start with half choke then she doesn't need it for the rest of the day. She starts up on the 1 or 2nd kick every time or a quick blip of the starter.
1977 CB750K Stock

Offline WarwickE36

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Re: Do you have to use the Choke to start your bike?
« Reply #20 on: August 22, 2011, 07:58:21 AM »
Quote
no wonder you get lousy fuel mileage.  It's running too rich, possibly to compensate for owner "improvements"?

is 40-45 MPG bad around town for a '74 550?  I can get close to but not quite 50MPG cruising at about 4K.

I have stock intake, honda filter, stock jets, idle screws set at 1 turn out, plugs are mint, headers are equally hot. 

The only time I NEED to choke the bike is if it is under 45 degrees.  That being said I do have to adjust the main idle screw to keep it idling, but only for a minute or so as it warms up.  Is there any negative affect from doing it this way?  I have to adjust the idle up even if its choked, so I figured without choke would keep the plugs from getting fouled.  Is there a danger of running to lean not choked, I would sincerely doubt it.  But I have been wrong before.
" Why does anyone get offended by what someone does to their own bike? I dont get it. "

You made me think about it after I cheered knowing someone else would like to know what these control freaks are up to.
 Every time any owner strips whatever precious Honda part the horrified purists parts go up in value. That's not the part that bothers them.
 What bothers them is they sat up late at night, their breast full of wonder and estrogen, unable to sleep, dreaming about their lovely darling and all her glory... and next thing you know someone else doesn't share their emotional deluge and their reaction is they must spread their mind museum as far as they possibly can, taking over as much of the real world as possible.

Drink fast, drive slow, but ride it like you stole it

1974 Cb550 with style
2004 SV650s

Offline bjatwood

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Re: Do you have to use the Choke to start your bike?
« Reply #21 on: August 22, 2011, 09:36:49 AM »
I bet my bike would get close to 50 if I just back off the highway 5K's a bit. But it sounds too good at 5K to slow down tho! LOL
Brian
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http://minibikers.proboards.com/

Offline Holubs

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Re: Do you have to use the Choke to start your bike?
« Reply #22 on: August 22, 2011, 10:57:00 AM »
My 750 F1 starts first kick with choke on full when cold, first kick rest of the day without choke on.  Stock except for a 1980 Kerker header and Pamco ignition. 

I rarely use the electric start because I have a short drive to work, so I don't like to wear down the battery.  (And it's fun to watch the Harley riders at work faces when they see someone start their bike by kicking it!)
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Offline excerpt

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Re: Do you have to use the Choke to start your bike?
« Reply #23 on: August 22, 2011, 12:26:52 PM »
74' 750k4

emgo pod filters
#45 slow jet
#115 main jet

the choke does nothing!
I've been wondering about this for a while. Bike runs better than it ever has, but still not perfect.
I moved up from a #40 slow jet to a #45 and the top end response was a LOT better. I thought it was only supposed to control low end response...LOL.

Any ideas?

Offline TwoTired

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Re: Do you have to use the Choke to start your bike?
« Reply #24 on: August 22, 2011, 12:56:46 PM »
no wonder you get lousy fuel mileage.  It's running too rich, possibly to compensate for owner "improvements"?

Mid 40's is "BAD".... I thought HONDA said that 42.23 MPG is what a early 750 should get milage wise? Did I read that wrong?  :o  And my plugs are a nice light brown color, not Black at all. Maybe I would get better milage if I didn't drive 70 MPH... and I KNOW I need a carb sync, my Buddy has a sync kit that he has promised to come over and do, but he's been too busy with his business to come over and do it.

No, mid 40's average is not "bad".  I don't know your 42.23 MPG reference.  Some have reported 50MPG or better with a CB 750.

At what throttle setting do you start up?
Are you aware that throttle position makes a big difference with the fuel mixture that's delivered?
You could have tan plugs with a lean Main, normal midrange, and too rich idle throttle positions.  Your plugs would show an average of all the throttle positions you used.  And show different deposit patterns if you changed your usage of throttle.

There are a lot of variables here.  But, if you are starting without choke, then whatever throttle position you are using during start is too rich and will remain so whenever that throttle position is selected thereafter.  You can burn off black deposits and turn them tan by running the engine lean at some other throttle position.

If your carbs do not have accelerator pumps, they must run rich to yield decent throttle response.  However, you should not be able to pin the throttle at low speed and have the engine pick up smoothly without engine wheeze.  If you can, then the low speed mixture is too rich.  It should accept up to 1/2 of total throttle travel and deliver smooth pickup (if not quick) in any gear from low RPM.

Until the air speed in the carbs increases to the point where the venturi provides the pressure drop needed to dominate fuel draw from the metering jets, the carb throat pressure is what makes the fuel flow.  That pressure differential is lost when the throttle is snapped open, and fuel flow is either curtailed or severely reduced, (just when the rider is demanding more).  It is common to run the carbs slightly rich at idle position in order to compromise engine needs with rider demands.  If the mixture was over rich at idle position,the throttle will not make the mixture over lean and cause wheeze.  Other other hand, if you make the idle way too rich it will begin to soot plugs during idle and be burned off when operated at other throttle positions.  It may even be set so rich as to not require choke when cold started.  The effect on MPG will depend on throttle position dominance during use, mitigated with the fact the idle position is still the most stingy fuel metering position even if set too rich.  However, it can still be said that the MPG would be better, if the pilot circuit was set more lean than way too rich.  If set correctly, you WILL need choke to start the bike when cold.  And the colder it gets, the more choke will be required.

Maybe an older post will help? : Understanding duct physics.
http://forums.sohc4.net/index.php?topic=83904.msg945765#msg945765

Cheers,
Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Those that learn from history are doomed to repeat it by those that don't learn from history.