Will a new CDI fix the WR stutter


24 replies to this topic
  • WR450SM

Posted May 27, 2008 - 04:08 PM

#1

Hey guys, I am just wondering......is the vortex CDI the only option to fix my stutter?

I have spent 9 months jetting in every way possible and the stutter is still there. James Dean posted some info about WR ignition problems at steady throttle and it certainly looks like a CDI problem that I am having. BTW the bike is an 07 and has done this since the day I bought it, TPS unplugged or not, the stutter is there. Jetting can minimize the problem, but never make it dissapear.

I need to know if a new WR CDI is a reasonable option, or maybe a YZ unit...or the most costly option - the Vortex ignition. What do you guys think?

  • headhunter622

Posted May 27, 2008 - 05:40 PM

#2

That is a lot of coin to drop on a guess. I have never personally seen one act like that but I guess it could be possible. If jetting makes a differance in the stutter I would doubt its the CDI. Have you tried an inlike spark tester to see if the spark is constant?

  • wartsnuff

Posted May 29, 2008 - 12:12 PM

#3

agreed,

if you can change the sputter with jetting, don't think its the cdi either

good luck

cheers
Warts

  • tweav

Posted May 29, 2008 - 09:10 PM

#4

by the way yz ignitions do not work on wr's unless you change everything . cdi ,coil and wiring. I'm fairly sure that the yz stuff all runs on ac and the wr stuff runs on dc.

  • Desracer

Posted May 29, 2008 - 09:24 PM

#5

Where is the sutter? steady throttle? need some more info, but steady throttle above 1/4 to 3/4 your to rich on the needle. If you have done this get another needle, I am running the YZ needle in my bike as neither the blue or red JD needle would work without constant tweaking.

  • lixno

Posted May 30, 2008 - 10:36 AM

#6

I think that everyone's right about the needle being too rich. When i changed the needle with one from Factory Pro (3rd clip position)the bike stuttered a lot at high rpm steady speed. Then i put the needle clip at 1st position and things became much better. When i changed it the problem was solved (but lost power)...

  • RocketScientist

Posted May 30, 2008 - 11:01 AM

#7

I have a YZ450 SM that had the same problem. It turned out the brand new Factory Pro needle was bent. I posted to your other thread as well. Let me know if this fixes your problem.

  • RocketScientist

Posted May 30, 2008 - 11:26 AM

#8

By the way, I have tried several combinations with my YZ ignition. I don't know it it will apply to your WR, but I hope this helps.

I haven't attempted an 03 YZ CDI. I originally had a slight stutter in my 04 YZ450. I put in a high compression piston and the problem was magnified greatly. Disconnecting the TPS helped. I switched to the 05 CDI and the stutter was again reduced. At this point the stutter was very slight. I switched to a Vortex CDI and had no noticeable change between it and the 05 CDI. I later modified the stator plate to make it adjustable so I can back off the timing to make it easier to kick start on pump gas. This seemed to help the bike run a little smoother on pump gas.

I now run the Vortex CDI, larger bore, stock compression, Factory Pro jet kit minus a bent needle and the bike runs great.

  • WR450SM

Posted May 30, 2008 - 03:51 PM

#9

Where is the sutter? steady throttle? need some more info, but steady throttle above 1/4 to 3/4 your to rich on the needle. If you have done this get another needle, I am running the YZ needle in my bike as neither the blue or red JD needle would work without constant tweaking.


Thanks for the response, I started this thread to see if anybody had fixed this problem with a CDI.

Yes the problem is at steady throttle, in the 1/8 to 1/4 throttle range. I have been through every circuit in the carb, getting the AFR correct with a Wideband O2 sensor. I have used 6 different needles to date. The jetting has been tried everwhere from 14.5 AFR down to 10.8 AFR in the stuttering condition, and the stutter persists. :thumbsup: :ride: :bonk:

I put an update in this other thread of mine:
http://www.thumperta...ad.php?t=629003

  • WR450SM

Posted June 10, 2008 - 07:37 AM

#10

It looks like I am going with a Vortex CDI. I will update when I get my hands on it and can do some testing.

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  • Demo_Slug

Posted June 10, 2008 - 10:19 AM

#11

It looks like I am going with a Vortex CDI. I will update when I get my hands on it and can do some testing.


Did you find any other options besides the Vortex and LeoVince?

  • Snakko88

Posted June 10, 2008 - 11:43 PM

#12

Jetted my bike on the dyno, still had about 20% of the stutter still there.
Bought a Vortex CDI. On the default setting stutter still there, on map 7 i think, stutter gone all together!

  • WR450SM

Posted June 13, 2008 - 12:18 PM

#13

Jetted my bike on the dyno, still had about 20% of the stutter still there.
Bought a Vortex CDI. On the default setting stutter still there, on map 7 i think, stutter gone all together!


Good to know! The vortex is on it's way....JD and I will be figuring out a time to get the bike on the dyno in the next few weeks. I'll keep you guys posted.

  • kikk0

Posted June 22, 2008 - 03:13 AM

#14

Hi! I'm about to rejet my 03 wr450 as I'm installing athena 480 bigbore kit. I'm also thinking about using a wideband o2 sensor. I'm just curious on what type you are using and if you're satisfied with it?

  • William1

Posted June 22, 2008 - 03:39 PM

#15

I run the DynoJet Wideband on my bikes. Innovate is supposed to be good too. You really need the data logging capability. Kind of hard to look at a mere gauge while riding. After I do some logging, I save the files to a PC. I wrote a simple program to graph the results. Here is one I did of my DRZ:
Posted Image

  • YamIan

Posted June 22, 2008 - 05:50 PM

#16

I have the same problem. I took the TPS off a buddies bike and put on mine. Stutter gone.

Now I'm on the hunt for a new or used TPS at a reasonable price. It disgusts me how much Yamaha wants for a piece of plastic and wires.

Anyone got an extra??

  • James_Dean

Posted June 29, 2008 - 11:40 PM

#17

Jetted my bike on the dyno, still had about 20% of the stutter still there.
Bought a Vortex CDI. On the default setting stutter still there, on map 7 i think, stutter gone all together!


We spent a good portion of Saturday testing WR450SM's ignition problem on the dyno. We tested both the stock CDI, and the Vortex CDI, and found repeatable results. ---Snakko88's comment is exactly what we found.

The graphs below show the stutter in 2nd, 3rd, and 5th gear under light throttle (less than 6hp) and engine speeds from about 4000 to 7000rpm. The engine speed on the dyno is measured by a electrical pick-up lead attached to the spark plug wire. Any irregularity in the ignition spark appears as "spikes" in the engine speed, and stuttering is felt as you are riding.

The first set of graphs is the stock CDI and the second set of graphs is the Vortex CDI on ignition map 7. Each graph was a separate recording, demonstrating that the symptom is repeatable. There were other ignition map settings with the Vortex CDI that had the stutter condition just like the stock CDI.

James

Stock CDI--

Posted Image

Vortex CDI Map #7--

Posted Image

The graphs below are the stock CDI in 2nd and 3rd gear with the power curve shown on the lower half, and the stutter shown in the upper graph. Note that the throttle position is very low, which results in the worst stuttering at the middle rev range--

Posted Image

The same graphs with the Vortex CDI in Map 7--

Posted Image

  • William1

Posted June 30, 2008 - 03:18 AM

#18

Interesting. Since the Vortex makes the same stuttering in a few of its' maps, and I have to assume it uses the same electronics for processing and sending a signal for all of the maps, could the difference be the amount of ignition advance? Any thoughts on tweaking the ignition sensor position slightly? Are you able to tell the amount of advance map seven has compared to the stock box and the other Vortex maps?

  • James_Dean

Posted June 30, 2008 - 08:18 AM

#19

WR450SM had already made attempts to eliminate his bike's misfiring by moving the TPS in both directions and disconnecting it, and RocketScientist modified the stator plate to make it adjustable. We don't know how much advance is made by each of the CDI boxes. The condition is most common when riding on flat roads at mid-rpms (4000-6000rpm) and middle gears where very little power is being made. Dual sported and motarded WR450F's and WR250F's are the types of bikes that will see the misfiring most often. This isn't anything new, as I recall the 2000 WR400F had the same symptoms riding on smooth roads.

--Riding in the dirt, I wouldn't notice it and didn't care whether the bike had the condition because during acceleration it goes away and the bike pulls smoothly.

James

  • WR450SM

Posted July 03, 2008 - 10:21 AM

#20

The latest update:

Got the bike out for a 20 mile ride the other day - and it is awesome :p The Vortex CDI solved the problem for all practical purposes. Just like the dyno graphs show, there may still be a stutter, but it is so small that I can't feel it (and I am very picky about this particular symptom). It is a night and day type of comparison....and with the handlebar mounted map selector switch it becomes very obvious. I switched back to map 1 while riding in the rpm / throttle range where the symptoms were the most pronounced before - and immediately the stutter was back, as strong as ever - then flip the switch to map 7 and it disappears :thumbsup:

Other than fixing the stutter / misfire / surging the Vortex map 7 showed a power increase down low with no change at peak and better power in overrev. I wasn't sure that I would feel the extra power, but I certainly can. Another interesting note, the bike starts very easily now, before I would usually have to kick it unless it was warm, but it fires up instantly with the easy button hot or cold after the new CDI.

My curiosity has me looking for an explanation of the differences between the original CDI mapping and the Vortex. Since Vortex did not provide timing curves in the documentation, it is all conjecture. I believe that the TPS compensation strategy is different between the 2 CDI's. Yamaha CDI performs better with respect to stuttering with TPS unplugged, Vortex CDI is better with TPS plugged in. Only more data would tell why, but I feel better running the bike with the TPS input.

Thanks to all who gave advice and support, especially James Dean who gave up the better part of his Saturday in an effort to understand why this issue is so prevalent on Yamaha WR's when other makes / models do not seem to have it at all. Thanks again James.




 
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