Starting The 250F..... AGAIN

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#3
Ivan read what you just posted and THINK about it. :)
 

JuliusPleaser

Too much of a good thing.
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#5
Will the '02 CDI work on an '01?

Or should I just raise my idle speed to facilitate easier starting? :p
 

biglou

#6
if the idle is set too low it won't start!
But if it won't start, how can you set the idle?
Also-Awfully hard to kick it at 1300-1400 rpm to get it to start.

Am I close here?:think
 

biglou

#7
It seems like circular logic to me. It won't start unless the idle is set at "X" rpm, but you can't set the idle speed until you start it. And when you are trying to start it, the engine rpm is essentially zero. That's all I was saying. Another question in my mind: How can the CDI know what you have the idle set at when the bike is just sitting there static, not running.:think Seems like the ignition spark would be the only input to the CDI to let it know where the engine speed is, and there is no battery. Or is there? Is there a small lithium batt in the CDI somewhere? Rich? Anyone?
 
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#8
These video's are sweet!! I'm tired of people always asking how hard my bike is to start! Here, look, it's that easy!!!:cool:
I've never had a problem starting my ever!! Well, except for the very first day I rode it, but then it's easy as 1-2-3!
 

biglou

#9
Originally posted by Truespode
The statement that it won't start is pretty inflamatory as it is describing an absolute
I didn't mean it that way. I was speaking theoretically. Kind of like the "If a tree falls in the forrest" thing. Maybe I'm just not getting it, but having the CDI know what your idle is set at before the bike is even running is kind of like running into the forrest to see if the tree did make a sound, thus unqualifying the original question.

Yes, once the engine starts turning, there are electrical signals going to the CDI. But, at that initial firing, the engine speed is not up to the idle speed yet, so how does the CDI know to continue to let the bike run? That was the gist of my original post.

Plus there are many factors that would influence what the idle speed will be that the CDI would not have an input from, such as the jetting, fuel screw position and idle screw position.

I'm not dismissing any of the original quote you posted, I just have these questions as to how the CDI processes the info it gets. Mainly, if it won't let it run unless the idle is , say, 1700 rpm, what lets the engine continue to run until it reaches that speed of 1700 rpm?:think

Isn't that why there are wires running to the carb? To operate the accel pump and communicate with the bikes ignition system? Remember the grey wire and how it effects the ignition of the bike?
To my knowlede, the wires running to the carb are for the throttle position sensor. I'm straining hard here, but I believe the gray wire deals with the ignition timing (relative to the piston's position in the cylinder) I will research this more to see if I can find out exactly what it does. I thought that the gray wire kept the ignition timeing somewhat retarded even at high rpms.I thought that was a WR-only issue, also? I think the accelerator pump is mechanical. I'll have to verify.
The rpm's would have an input to the CDI as would the position of the throttle via the TPS, the gray wire would enable/disable ignition timing advancment/retardation based upon these inputs. Yes? No? Maybe? Time to do some reading.
 
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biglou

#10
Ivan-I was just reading (elswhere:o ) that there seems to be an issue with low spark energy during the initial kicking. That was a thought I had, having some previous experience with generators for self-sustaining engines. We used an external electrical source until the engine had reached a high enough rpm so that the on-board generator could produce enough juice to keep things going. Different application but similar systems: Ignition, fuel control, etc. I could be wrong, but I'm willing to bet that the CDI box, in general, is not overly complex from an electronics standpoint. Maybe I'll go home and cut the heart out of my pumpkin and open her up! Nah...

On the accelerator pump, check out this Email I just got from Blue Thunder (Jason). We have been kicking this around for quite some time, ever since I had the DRZ. Now that he is sidelined, we may get to it for his 426. Anyway, check this out:
Actually..I might have a project for us, I have been trying to nag my brother into helping me perform the "BK" mod. It is a carb mod from Brian Kinney, Tim Ferry's mechanic. You have to drill and tap a tab on the carb, put an adjustment screw in and change the timing/duration of the spray from the accelerator pump. I have all of the documentation and pictures, everyone that has done is amazed at the power difference and ease of starting. Brian told me the bikes pump is way too rich from the factory and that is what caused my cold fouls this winter. Anyway, with your attention to detail and surgeon like nerves, we should be able to do it. A sixteen year old did it to his and 2 of his friends bikes...so I would hope we could do it. Once things get a little better for me, I can load her and do it in the surgical lab(your clean garage). Let me know what you think, if you need any specifics, do a search for BK carb mod on Thumpertalk under the YZ forum. It is interesting stuff. J
Does anyone have any direct experience with this? (Not to stray too far off topic here).
 
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#11
Ivan - Changing the idle adjustment CAN have an effect on starting, but it has to do with the slide position and it's effect on pressure differntials in the carb. For the starter circuit to function it has to see a pressure difference between normal atmospheric (provided through the vent tubes) and the pressure in the carb throat in the slide area. Changing the height of the slide will change the speed of the air through the slide opening and the pressure along with it. So it makes sense that a specific rpm setting could translate to a specific slide opening that optimizes the functioning of the starter circuit. But as Lou pointed out the rest of it is flawed logic at best. :)

I wouldn't be surprised if the '02 ignition system or the magneto itself is designed to function better at a lower cranking speed. Given how difficult it can be to kickstart the 250F at times but how easily it starts by spinning it up faster via a push start, it makes sense.

I sent an e-mail to Okie yesterday asking him if I could test an ignition related item on his bike in an attempt to improve starting. A lot of people have been suspicious of the ignition on the piglets. If my test works out I'll let you guys know.
 
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#12
and he promised not to nuke my piglette.:scream:

Oh and by the way, the BBR kickstarter turns it over faster than stock :)
 

biglou

#13
Originally posted by Okiewan:
Oh and by the way, the BBR kickstarter turns it over faster than stock
That was one of the things mentioned to help in starting the baby thumpers. Increases initial rotating speed via shorter lever arm(kickstarter), if I am visualizing this correctly.
 
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#14
help me explain it Rich...
it also has to do with the different shape. No doubt shorter riders will appreciate it as well.
 

JuliusPleaser

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#15
I'd be VERY interested in '02 CDI test results. I'll even offer my F as a sacrificial lamb. I only have trouble starting the bike when I'm wasted and the bike is very hot. Could it be that I'm not able to spin the motor fast enough to activate ignition?

That's the benefit of the shorter starter, correct? More RPMs from the same effort?