# Starting The 250F..... AGAIN

Mi. Trail Riders

B

#### biglou

Oh! Oh! Oh! Mr. Kotter! Oh! Oh! Oh!...:)

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

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

B

#### biglou

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

B

#### biglou

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?

#### J_dem_Bones

Member
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!

B

#### biglou

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.

Last edited by a moderator:
B

#### biglou

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).

#### Rich Rohrich

##### Moderator / BioHazard
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.

#### Okiewan

and he promised not to nuke my piglette.:scream:

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

B

#### biglou

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.

#### Okiewan

help me explain it Rich...
it also has to do with the different shape. No doubt shorter riders will appreciate it as well.

##### Too much of a good thing.
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?

#### Jon K.

Whatever the benefits are they can't be more RPMs from the same effort; :) even the BBR people can't violate the basic physics of that one.

#### Rich Rohrich

##### Moderator / BioHazard
Originally posted by wfo74
Whatever the benefits are they can't be more RPMs from the same effort

That seems to be the real issue here. The shape of the stock kickstarter makes it difficult to get your leg in position to get complete follow through (especially when wearing a brace) . A modified shape should improve follow through, so the full force is applied over a greater range of motion. I doubt it's a cure all, but anything that keeps you from from having to draw your knee to your chin to start the bike will be a help :) Proper jetting and possibly an ignition change will likely pay greater dividends.

B

#### biglou

Also-Heat?

Getting ready to open up a CDI from a friends older Yamaha (coincidentally) street bike to look for cold solder joints. He got some info off a site related to his bike (Virago?) and wanted me to take a look at it.
I wonder if the heat rising from the motor on the F's is having an effect on the electronics in the box? That could certainly change the characteristics of some of the electronic components if they are not rated to that temperature, whatever that may be after heating up. We will be looking to replace certain components that are not at or above a certain temp rating per the instructions downloaded from that site.
As for the shorter kick lever, if I have this correct, the same leg speed will move the fulcrum (kickstart shaft) at a greater rotational speed, thus turning the engine over faster, providing a stronger spark. A redesigned shape to make this more ergonomical makes sense to aid in the effort. And yes, it would take a "stronger" kick (more force) to keep the same leg speed since you have effectively shortened your lever.
I remember kicking over Jason's 426 this spring after a few hours on the DRZ(magic button:) ) and just raising a leg that high after being in the saddle all day will draw your attention to your obliques in a hurry! Of course, that doesn't take much for me.:)

Last edited by a moderator:

#### DougRoost

All this ignition talk makes me wonder one thing: would a Nology HotWire help? I know this is a controversial thing and I think the "physics" on their Web site is rubbish (see previous post on HotWire). But I will say that KLX owners found this to make starts, hot or cold, a one kick affair vs. many, many kicks. I believe the capacitor in their is crutching a weak ignition, especially at low RPMs (i.e- kickstarting).

My point is, for less than \$40 and a few minutes effort, it's probably worth someone trying. May even give more insight into the CDI box comparo. Again, it may only be a crutch but it may be all this little wonder thumper needs. If so, owners of older 250f's could have a very inexpensive and quick solution vs. securing the much more expensive '02 CDI. If not, then there's some data to show the HotWire had no effect and that would be good to have as well.

I also find it very interesting that the 400/426f owners, inlcuding many friends of mine, don't have nearly the starting headaches as the 250f owners do. All my friends with these start first or second kick every time, not or cold. Perhaps the 250f engine is really on the edge (timing, compression, cams, bore/stroke ratio, etc) to compete against the 125 2-smokes.

BTW, I've read blue bike threads with great interest as I've considered one for some time. However, being only 5'8" tall, my modified KLX with a planned move to a KTM 400 E/XC is probably the better strategy for me. Maybe I should search on this or start a thread on the blue thumpers for vertically challenged riders...

#### DougRoost

My understanding is you can use a HotWire with any type of spark plug. Of course they recommend a brand and type they sell, but it's not required. I'm sure they'll work on Yamaha thumpers since Nology recently developed a long reach boot version for DOHC dirt bikes, the most popular of which is of course the blue bikes we're discussing here (have this wire on my KLX).

In fact, they make 2 comments on resistor plugs. From the instructions that came with mine:

"HotWires for Motorcycles are compatible with all stock and most aftermarket ignition systems and are street legal. HotWires for Motorcycles are RFI and EMI protected and should not interfere with any onboard electronics devices. (See disclaimer on back of sheet)."

"HotWires will provide the largest performance gain when non-resistor spark pluigs, with a resistance of less than 0.5 Ohms, are used."

Interestingly, on the back is a disclaimer:
"Spiral Core HotWires cannot be used on some engines with programmable ignition systems without installing resistor spark plugs. Rough engine idle and/or misfire can develop."

#### bud

Member
a 2 stroke rider's point of view

I have also been thinking about getting a 250f. I got to test ride a demo wr250f recently, and was impressed with the power in the mid-range, and the handling and cornering (once I got a bit of a feel for it). But I couldn't start it, though the jetting seemed good and was tweaked on the day, and I have not much trouble starting a 426. According to the 4 stroke gurus who were with me (some of whom were also riding the bike for the first time), it needed a very hard kick from the exact right spot. My impression at that point was "f&*# that". My husky starts with little more than a nasty look. Had the 250f started that eailsy, it might be in my garage right now... Now I think my first 4 stroke will be a 02 husky (electric start :))

#### Rich Rohrich

##### Moderator / BioHazard
Re: a 2 stroke rider's point of view

Originally posted by bud
. According to the 4 stroke gurus who were with me (some of whom were also riding the bike for the first time), it needed a very hard kick from the exact right spot.

Based on initial impressions of the BBR kickstarter Okie fitted to his 250F I'd say the shape of the kickstarter plays a big part in this. It seems to be much easier to get a full sweep kick with the revised geometry. I'll reserve final judgement till we see how it acts with a muddy boot after flipping the bike over a couple of times when it's hot, but this looks to be a real step in the right direction.

#### holeshot

##### Crazy Russian
.

Of the 250F riders I've spoken directly to, some say the YZ250F is a little more quirky than the YZ400/426F when it comes to starting, while others claim that it's about equal. :confused:

The last item I had that required an instructional video on starting was my weed whacker (two stroke). And yes, the video was necessary. You can be sure that Honda won't be putting "how to start the sucker" instructions and videos on their website for the CR450F and rumored CR250F.

I've taken test rides on the YZ250F, and now I want to replace my 426 with it, but I would change to a shorter kickstart right away. The BBR is 1" shorter than stock and the ProTec is 1.5" shorter than stock and a clean design. Does anyone have any "real life" experience with the ProTec? Website below -

http://www.pro-tecperformance.com/protec_kick_starter.htm

The starting issue has me holding for the CR250F or even considering a 125 two stroke as a second bike. Whether Yamaha's changes to the '02 ignition make it easier to start or not, remains to be seen.

Replies
2
Views
3K
Replies
14
Views
3K
Replies
3
Views
4K
Replies
9
Views
2K
Replies
5
Views
11K