How to cold start - Page 2 - Suzuki GSX-R Motorcycle Forums Gixxer.com
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post #21 of 50 (permalink) Old 11-06-2012, 11:21 AM
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Re: How to cold start

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Originally Posted by dj_smurph View Post
On my aprilia rs125 opening the choke opened up an extra jet to allow more fuel to flow.
That's how my GS500 carbs did it too!
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post #22 of 50 (permalink) Old 11-06-2012, 11:33 AM
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Re: How to cold start

I gave you guys the mechanisms....now another set of hints
First...the slide in a CV (constant velocity) carb opens(rises)andcloses(falls)based on pressure differential between what is above the piston vacuum slide and diaphragm, and what is below it in the venturi.....at idle upon start with closed throttle there is almost no vacuum underneath.
Secont, what fuel circuits upstream and downstream of the mechanical butterflies are in effect at idle and cold start.
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post #23 of 50 (permalink) Old 11-06-2012, 11:41 AM
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Re: How to cold start

I'll just wait on the right answer then I'll copy your test. Or Or .... I'll just put my name on your test!
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post #24 of 50 (permalink) Old 11-06-2012, 11:43 AM
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Re: How to cold start

That crossed my mind, the needle would only be used at higher rpm, at idle usually only the pilot jet is putting fuel in...but I have limited experience with carbs, these ones might used the main jet for choke... (wrong guess)

Anyway, I might have making some confusion here with the venturi/intake.
So, if there is an opening between the venturi and the diaphragm, it would equalize pressure, right?
Then it would require more rpm to the slides (and needle) lift...altough, at idle it would NOT lift anyway, what is the point?!
Long live FI....

Last edited by tmp; 11-06-2012 at 11:44 AM. Reason: missed a NOT before the lift!!
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post #25 of 50 (permalink) Old 11-06-2012, 12:33 PM
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Re: How to cold start

This is the reason I sent ccmhunt my carbs. I wouldn't know where to start with them. It must then affect the pressure differential ( exaggerate the differential?) achieved across the carb therefore allowing more fuel to flow for a given amount of air
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post #26 of 50 (permalink) Old 11-06-2012, 01:59 PM
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Re: How to cold start

I am glad I am not sending my carbs to you guys.....
The ideas have merit, you are each onto something.....
When I set back to my shop I will arrange a little experiment.
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post #27 of 50 (permalink) Old 11-06-2012, 02:02 PM
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Re: How to cold start

You're having fun with this, don't you?! Grrr....
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post #28 of 50 (permalink) Old 11-06-2012, 02:11 PM
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Re: How to cold start

I like thought, it's one reason I like carbs and motors, it's also why I am excited to degree the cams it williamhbonney motor soon, you have to use all that math you thought you would never use once you left school
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post #29 of 50 (permalink) Old 11-06-2012, 02:27 PM
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Re: How to cold start

Not answering/Guessing till tomorrow...

I wish I never deleted my pm's
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post #30 of 50 (permalink) Old 11-06-2012, 02:33 PM
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Re: How to cold start

I like thought, as to why I go insane working in this place and have daily migraines.
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post #31 of 50 (permalink) Old 11-06-2012, 02:54 PM
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Re: How to cold start

Allow me to be the first to answer the question: depending on the temperature I'll use full choke (/fast idler) and no throttle or if it's cold, full choke and a hint of throttle.
This on FI.
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post #32 of 50 (permalink) Old 11-06-2012, 07:34 PM Thread Starter
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Re: How to cold start

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I allways tought that the choke mechanism would allow more fuel in the same conditions.

I'm not sure why, but from what ccmhunt wrote, if there is an opening from the engine intake to the vaccum chamber, it would create more vaccum, lift the needle higher then letting more fuel in at the same rpm.

To the OP...that on the left handlebar is a fast idle, it's not a choke, altough it is used to help starting in the cold. My FI 750 has that too, and sometimes she is a bitch to start in the cold weather. Try making the pump prime two times, and blip the throttle while pressing start. Still, a bitch to start but helps a bit.
If she is very very hard to start then I would check the valves, throttle sync, and ECU repro if you are using aftermarket filter+exhaust...
WOW! Only half way through this post and as always good info. Okay with this quote I have a question(s): when you say "blip the throttle" do you mean "twist the throttle"? I thought having a FI you didn't have to do that. Just asking, many thanks for all the responses.
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post #33 of 50 (permalink) Old 11-06-2012, 07:40 PM Thread Starter
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Re: How to cold start

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Allow me to be the first to answer the question: depending on the temperature I'll use full choke (/fast idler) and no throttle or if it's cold, full choke and a hint of throttle.
This on FI.
Thanks for this info. I'll try this on my FI. So if I give it a "hint of throttle" this will put fuel into the motor like a carb? So what do you do when it's not cold? No choke/fast idler and a "hint of throttle"? Sorry for silly/noob questions. Another reason why I love this forum.
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post #34 of 50 (permalink) Old 11-06-2012, 08:18 PM
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Re: How to cold start

lol armi... you described the choke that you would find on a carbureted car or truck lol not that you can find many of them anymore too.. this is the kind of thread that could drive chris to drink.. well this and thread about bells and tyre paint
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post #35 of 50 (permalink) Old 11-06-2012, 08:20 PM
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Re: How to cold start

how cold is cold to you?? full choke (fast idle) on the left control and hit the start button and it should fire up even at 0c my 99 starts fine. one ? do you know how old the plugs are in the engine??
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post #36 of 50 (permalink) Old 11-06-2012, 09:05 PM Thread Starter
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Re: How to cold start

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how cold is cold to you?? full choke (fast idle) on the left control and hit the start button and it should fire up even at 0c my 99 starts fine. one ? do you know how old the plugs are in the engine??
Not that cold here yet, only getting down to the 40's at night. Bike has had a full tune-up, plugs are only 4 months/600 miles on them. I have tried full choke/fast idler, no throttle and hit start and does not start right up. I have to do it two to three times and no "hint of throttle". Do you use a "hint of throttle" at full choke/fast idler?
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post #37 of 50 (permalink) Old 11-06-2012, 09:17 PM
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Re: How to cold start

Ok that's my bad I thought 99 was the first year of fuel injection.
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post #38 of 50 (permalink) Old 11-07-2012, 01:52 AM
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Re: How to cold start

Quote:
Originally Posted by TT750 View Post
lol armi... you described the choke that you would find on a carbureted car or truck lol not that you can find many of them anymore too.. this is the kind of thread that could drive chris to drink.. well this and thread about bells and tyre paint
I told you I quickly googled it

Will be having a look at this puzzle later
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post #39 of 50 (permalink) Old 11-07-2012, 08:47 AM
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Re: How to cold start

Have you looked at you wire harness? You might have a half burned up plug to your stator or r/r. Mine was fine all season and suddenly it was starting hard. One wire in the plug to the regulator was melted but still making some kind of connection.
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post #40 of 50 (permalink) Old 11-07-2012, 09:14 AM
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Re: How to cold start

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Originally Posted by andergar View Post
Not that cold here yet, only getting down to the 40's at night. Bike has had a full tune-up, plugs are only 4 months/600 miles on them. I have tried full choke/fast idler, no throttle and hit start and does not start right up. I have to do it two to three times and no "hint of throttle". Do you use a "hint of throttle" at full choke/fast idler?
Without throttle it's the same for me, third time's the charm. I've wondered the reason for this myself.

On FI bikes the choke lever turns the same mechanism as the throttle, so giving it a little bit of throttle is like giving it more choke (or using the choke lever is like giving it a little bit of throttle).
When it's warmer there's no need for throttle for me and when the engine is warm it starts fine without the choke/fast idler as well.

Kind of silly that these early FI Suzukies even have the fast idler lever... At least the newer ones are smart enough to keep themselves running.
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