Author Topic: Choke & Stalling?  (Read 2520 times)

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Offline keith5

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Choke & Stalling?
« on: June 10, 2012, 07:56:08 AM »
Hi all -

Recently purchased a 77 CB750A in blue. Runs well (after it's warm that is) and in good condition. However can someone please tell me what the trick is with the choke so that when I start off the bike doesnt stall out on the first stop sign I hit??

The bike fires right up when I pull the choke, I let it sit and then it idles down to the point of stalling out unless I pull the throttle a couple times. If I push in the choke lever too soon it will definitely stall out. However if I let the bike sit even for a few mins to warm up and then head out, the bike stalls as soon as I dont rev the engine a couple times. This is hard since the bike doesnt have a clutch... so in order to rev the engine etc to keep from stalling out I have to push into neutral etc at the stop sign(s) which isnt safe!

AFTER the bike is really warm and I push in the choke lever it runs great with no issues. it idles fine and will not stall out. Do I really need to let the bike warm up for like 10 mins before I ride? Can I start it up and just ride it with the choke lever pulled up for awhile till it warms up, and then push the lever in? Is it safe to even ride with the choke lever pulled up?  Im starting the bike in 80 degree whether, so its not THAT "cold".

What are your tricks? Already had the bike stall on me on the road twice which isnt fun!

Thanks!

Offline raymond10078

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Re: Choke & Stalling?
« Reply #1 on: June 10, 2012, 02:44:43 PM »
Have you set/adjusted the idle mixture - and just as important, the idle speed?

Does the idle speed dashpot work (to slightly open the throttle when in gear)?

Also - there is a choke speed adjustment, too.

That is where I would start.

See the service manual - available on this site.
« Last Edit: June 10, 2012, 03:40:29 PM by kandrtech »
1978 CB750A (upgrading very, very slowly)

Past bikes - Honda: SL350, CX650C, CB900C, CB1000C, CM450A; Kawasaki: several 1972 750 H2's; Suzuki: TC90J.

Bikes I want: CX650ED, a mid-sized japanese V-twin with ABS.

Offline 77Pinto

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Re: Choke & Stalling?
« Reply #2 on: June 11, 2012, 05:26:07 AM »
All my SOHCs have been cold-blooded. 

Remember that they made these to run at higher temp.s than that water cooled engines do, and there are lots of fins pulling all the heat away from the cylinders.  All that metal needs to get warmed.

I agree with what was stated above, in order to minimize problems, the bike needs to be in tune and everything working correctly.



Bill

Offline BobbyR

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Re: Choke & Stalling?
« Reply #3 on: June 11, 2012, 08:52:33 AM »
I start it with the choke, let it get run while I put on my gear. I push in the lever 1/2 and ride to the corner. It is a blind curve corner so I use the choke so I won't  stall. Once I am up to speed i push it in and let the bike warm up on it's own. I have a 78K so my setup may be different than yours.
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Offline keith5

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Re: Choke & Stalling?
« Reply #4 on: June 26, 2012, 06:39:59 PM »
Thanks all! Just wanted to follow up on this in case my case helps others.

You were all right... The problem wasnt warm/cold engine or the choke, it was the overall idle speed after I performed the oil & air filter maintenence. I played with the idle adjuster a bit and sure enough, its idling like a champ again.

One note: the bike starting stalling bad after I changed the oil and filter, and also cleaned the air filter and breather element. The breather was filthy, not sure if previous owner ever cleaned it. I think that it being cleaned may have greatly increased the amount of air coming in/out, which threw off what was previously a healthy idle speed. The bike was just dying unless I throttled. Just a theory.

The choke advice was very helpful too, though, as it helped as well.

As for being in tune, I still have some work to do in order to get it there. Its in good shape but is due for the general maintence which Im working through. A bit overwhelming and no mechanics around here want to tune it for me (all either service Harley only or just say they wont get to it for over a month).

Thanks again.
« Last Edit: June 26, 2012, 06:47:11 PM by keith5 »

Offline Sitarz84

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Re: Choke & Stalling?
« Reply #5 on: July 18, 2012, 07:53:20 AM »
I just bought a 77 Honda 750 and it sounds like I'm having the same problems you were having. I'm brand new to the motorcycle world so I'm glad I found this thread.
You said that you did regular maintence with the Oil and Air filter...I'm going to give that a shot on my bike.
You also said that you messed with the Idle Adjuster. Where exactly is that and what does that look like?

any help and advice is much appreciated

Offline raymond10078

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Re: Choke & Stalling?
« Reply #6 on: July 18, 2012, 09:52:22 AM »
1978 CB750A (upgrading very, very slowly)

Past bikes - Honda: SL350, CX650C, CB900C, CB1000C, CM450A; Kawasaki: several 1972 750 H2's; Suzuki: TC90J.

Bikes I want: CX650ED, a mid-sized japanese V-twin with ABS.

Offline Sitarz84

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Re: Choke & Stalling?
« Reply #7 on: July 18, 2012, 10:45:10 AM »
ok thanks...this guy refers to the service manual. I only have the operators manual. My guess is that they are different.
Ill have to find this throttle adjuster and play around a little bit and see if I can get the results I'm looking for.

Thanks for the help

Offline raymond10078

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Re: Choke & Stalling?
« Reply #8 on: July 18, 2012, 11:27:53 AM »
Look here.
1978 CB750A (upgrading very, very slowly)

Past bikes - Honda: SL350, CX650C, CB900C, CB1000C, CM450A; Kawasaki: several 1972 750 H2's; Suzuki: TC90J.

Bikes I want: CX650ED, a mid-sized japanese V-twin with ABS.

Offline Sitarz84

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Re: Choke & Stalling?
« Reply #9 on: July 18, 2012, 11:36:19 AM »
yeah i just saw that as soon as i sent you the message...ill be printing out the whole thing as soon as i get home