07 Sputtering at high speed- is this normal?


32 replies to this topic
  • Fullbore4

Posted February 09, 2007 - 12:41 AM

#21

Sorry but its tucked up behind the frame in the direction of the arrow on your bike. Its not on my 06.

Posted Image

  • alexrobinson

Posted February 09, 2007 - 05:42 AM

#22

TPS Sensor. I am sure I will not be popular questioning other peoples advise, but I can tell you my experience with Stuttttter and the TPS on my WR450 2004 UK model. I had the Stuttters and did as Thumpertalk members suggested and disconnected the TPS and yes it did make a huge difference, stutter almost dissappeared! Excellent! Had my 04 model for about a year and took it to a local DYNO tuning centre, I was happy with the bike but I was looking for a little more tractability on rocky slippery hill climbs. I told the DYNO tuner that I had disconnected the TPS. He re-jetted my bike, it was running too lean so he put in a bigger main jet, adjusted the needle and adjusted the air screw under the float bowl and he re-connected the TPS and RESULT AMAZING! The DYNO doesn't lie, from memory I gained over 10% on HP and Torque, but the actual riding difference of the bike really was amazing so much more tractable and NO STUTTTTER at all! So in my experience if disconnecting the TPS helps with the STUTTTER you have a jetting problem! Get a professional with a Dyno to jet your bike properly and re-connect the TPS.

Oh yeah, another contreversial subject while at the DYNO with my UK 2004 model I explained about the Grey Wire Modification, we ran the bike on the Dyno with and without the grey wire and there was no performance gain!

Just got my 2007 model WR450F and I am still prepping it and will run it in this weekend, when I get a few hundred miles on it to bed everything in I am straight back to the DYNO shop to get this bike running correct from the start. I think it cost me £120 last time, but in my opinion money well spent!

On my 07 model I have done the throttle stop mod, removed the restrictor from the exhaust and made a blanking plate to remove the AIS system as described by one of the TT members, plugged the hole in the Air Filter Cage (I never would have noticed that hole without Thumpertalk!) Thanks to all the TT members who have posted advise on how to access the carb on the 07 model, without their posts I would never have managed to access the carb!

I am waiting to go to the DYNO to see if the Grey Wire Modification on the 2007 model does actually make a difference and the same time see if removing the Airbox Snorkel shows any difference on the DYNO.

Unfortunately the lovely new 07 model Tail-Light is no use here in the UK because there is no way to modify it to be able to hang a Registration Plate on - so I have mounted the Acerbis LED Tail light with number plate holder which fits and looks good! Wired in front and back brake light switches (Genuine Yamaha ones are best with braiding and a 90 degree rubber cover) and a fitted a horn.

Sorry I got a little distracted from the original STUTTER question - my answer is to get your jetting set up correctly at a DYNO tuning centre. The DYNO doesn't lie. Or the alternative is lots of Trial and Error trying different jets on a Carb that is such a mongrel to access- If you decide on the Home Trial and Error basis I think from the positive comments from TT Members you should invest in the JD Jetting Kit? or better still take the JD Kit to a DYNO tuner.

I will let TT members know if the DYNO shows any performance gains on my 07 model for the Airbox Snorkel removal and the Grey Wire Mod.

Cheers, Alex Robinson - UK

  • alexrobinson

Posted February 09, 2007 - 06:15 AM

#23

Ooops, sorry just realised you already have the JD Jetting Kit.

Good luck and from my 2004 experience correct jetting will get rid of the dreaded STTTUTTER.

Cheers, Alex Robinson -UK

  • Humunn

Posted February 09, 2007 - 06:17 AM

#24

Great info Alex!

  • CSS9961

Posted February 09, 2007 - 09:46 AM

#25

I haven't had the chance to ride my new 450 yet, but I eagerly await alexrobinson's results!

My plan is to ride it stock for awhile, then do the mods... And only the ones that really make a difference.

Please update us when you get the Dyno results! :censored:

  • Island Boy

Posted February 09, 2007 - 11:13 AM

#26

Thanks to TT and everyone that took part in this discussion, I received some really good advice. Thru process of elimintion, I will change needle from blue to red first along with AIS removal, then mess with TPS if I have to. The jetting: 170 main and 48 pilot should be OK (I hope). Cheers!

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  • James_Dean

Posted February 09, 2007 - 11:50 PM

#27

TPS Sensor. I am sure I will not be popular questioning other peoples advise, but I can tell you my experience with Stuttttter and the TPS on my WR450 2004 UK model. I had the Stuttters and did ....

Oh yeah, another contreversial subject while at the DYNO with my UK 2004 model I explained about the Grey Wire Modification, we ran the bike on the Dyno with and without the grey wire and there was no performance gain!....


Cheers, Alex Robinson - UK


Alex,

Most dyno tuners use only full throttle to evaluate the power. If you take more time to evaluate different throttle positions, the results are significantly different with the Grey wire connected and disconnected.

The following graphs are results from holding a steady throttle at 1/8, 1/4, 3/8, 1/2, etc. Notice how only full throttle looks identical, while the lower throttle ranges have major losses with the grey wire connected.

James

---Grey wire connected on the WR250F---

Posted Image

---Grey wire disconnected on the same bike---

Posted Image

  • alexrobinson

Posted February 10, 2007 - 01:50 AM

#28

Hi James. Excellent! thanks for the great info on the Grey Wire. Like you said I am sure that my Dyno Guy didn't check the differences at different steady throttle openings. Your results show an amazing difference! I will get the Dyno guy to check it out on my 07 450 but judging by your results the grey wire is going to be disconnected on this bike. I will let you know the results.

Excellent, thanks again!

Cheers, Alex Robinson -UK

  • Island Boy

Posted March 06, 2007 - 06:34 AM

#29

Thanks to SC / Fullbore4, you guys were spot on! I changed my JD needle from Blue to Red 4th clip and no sputtering at all now! The bike is extremely smooth at high speeds. The popping on deceleration was also reduced by 70%... Still waiting on 07 AIS Kit from my supplier. NO NEED TO DISCONNECT OR ADJUST TPS! :applause:

  • TheCure

Posted March 06, 2007 - 02:17 PM

#30

Forget it.

  • clark4131

Posted March 06, 2007 - 02:27 PM

#31

Ease down sparky, it's just jetting :applause:...SC

  • TheCure

Posted March 06, 2007 - 02:43 PM

#32

#1 reason not to post an opinion. You can't have one.:applause:

:lol:

  • jim_wr250f

Posted March 06, 2007 - 11:10 PM

#33

I got my bike back from the dealer yesterday aswell. all fixed and all they did was changed the needle setting. Hmm they did 50kms though. my bike was probably the demo model or the run about.




 
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