wrf450 2003 misfiring at 1/4 to 1/2 throttle
Posted January 31, 2014 - 11:20 PM
Posted February 01, 2014 - 12:12 AM
If it's rough I would guess too rich. Lean generally feels gutless.
Put the clip on the needle 1 or 2 positions closer to the top.
But to be sure you should remove carb and list all jet sizes and needle model and clip position and list them here.
Fuel screw (2 turns out)
Needle (OBDTM )
Clip (2nd from top)
There other reasons but start with the easy to fix stuff first.
Posted February 01, 2014 - 05:23 AM
sounds like normal to me
WR's not designed to cruise at constant speed - not enough flywheel weight
They do cough, splutter and generally mis-behave if you try to do this
Posted February 01, 2014 - 06:41 AM
The '03 and later WR's have a 'defective' ECU module; specifically the mapping curves.
It is made up of (3) 'sub maps', all dependent on rpm and throttle position.
1. Closed throttle, 2. partial throttle, 3. Wide open throttle.
At the sub-map 2 point (partial throttle) the ECU can't decide between sub-map 1 (closed throttle) and sub-map 2, so it toggles between them. WOT (really before wot) goes to sub-map 3.
The quick fix is to unplug the TPS (at the harness, not on the carb). This will put the ECU in sub-map 3 all the time. A bit less throttle response at low rpms will occur.
The better fix is the PROPERLY calibrate your TPS, using the 9v battery method. The method in the service manual is actually not correct IMHO.
For some, this solves the problem.
For many, it just makes it different.
You must calibrate the closed throttle position with the slide dropped to the bottom (as in below idle)
The best fix is to put on a dynatek FS ignition system, and choose the stock (modified by dyna) Map #3, which has modified sub maps 1/2/3.
The Dyantek also allows you to calibrate the TPS in about 15 seconds, change the sub map turnover points, and advance your timing as you choose.
All stutter is removed in Map #3
I run Map #2, which I modified for performance only. The 2800 rpm stutter is still there, but I moved it down to 1/16 throttle with the adjustable maps, which is rarely ever used, so I only notice it on the street at certain times.
Edited by TheKoolAidMadeMeSick, February 01, 2014 - 06:46 AM.
Posted February 01, 2014 - 11:04 AM
Here's the deal:
You bought a 12 model year old bike with no idea the jetting it has in it and jetting is one of those things every goofball with a screwdriver thinks they can do. So what you need to do is start with a KNOWN baseline by completely cleaning the carb from top to bottom making sure all passages are clear. Read all the pinned threads related to "the bog" and jetting no matter how much you think you know. Then write down all jets and settings based on the chart Thommo listed above while you're in there. At that point compare what you have to what others have written about and either buy a JD jetting kit, or the individual correct jets for your bike again based on this forum.
At that point you should be good to go and only need minor tweaks to get it 100%. As well, make sure your valves are in spec, your air filter is clean, your timing is on and your cam chain isn't stretched past it's wear limit. Double check your exhaust pipe is on correct, all gaskets are in place and your silencer is in good shape packing wise. Do an oil change too along with a fresh tank of gas.
Now you're ready to go engine wise. Lots if info on body and frame stuff but before you go chasing all over be sure it's ready to run and be able yo know you're not chasing phantom problems.
Write back what you get, we're here to help.
Edited by miweber929, February 01, 2014 - 11:05 AM.
Posted February 09, 2014 - 11:57 AM
Posted February 09, 2014 - 05:10 PM
thanks for the replies it seems it has something to do with the tps as when I unplugged it and took it for a ride it seemed to fix it, and when I plugged it back in it would do the same thing again, is it bad for the bike to run it without tps untill I find a new tps??
Your TPS is not defective. Read my post above.
Posted May 14, 2014 - 04:13 AM