Jetting Qs

Nooffseason, The local KTM dealer has a dyno but I’ve been too lazy to take mine in. :) It’s quite an ordeal because the knobby tire has to be changed with a more streetable tire to work right on the drum etc., etc.

After I re-jetted and did the BK mod throttle response was superb, as far horsepower gain I’d have to say yes but by how much I don’t know.

In retrospect after all the mods I’ve done to mine, you will get the most performance out of your re-jetting if you YZ time as well, IMHO.

Wow this thread is almost a year old.

Funkster....Good to hear from you....

The funny thing here is that there are more post's on this one thread than in your entire lifespan on TT....Remarkable...

You and Lewis are still battling it out for the most posts and longest duration, this is cool...

Bonzai :)

I don't know how I missed JD's post. I guess I've been concentrating on back to school stuff (see my back to school post for some detail!.

My jettng could be lean enough to do damage to an unrestricted machine.

I'll get my notes together and bring you up to date tommorow.

[ August 28, 2002, 05:31 PM: Message edited by: tbronc ]

Here..this may make it easier for the newbies..instead of searching :)

Yamakaze

What Jetting are you running on your WR450 VS. YZ450 ?

stinking jetting, the last domain of the dirt bike.... everything else is a self calibrating fool.... injection. Everybody has there fave, some like it lean others rich most don't have a clue. Sure a tweak here and jet change there can change a modern dirt bike big time but let the motor talk. I've opened the airbox big time (new battery cradle and all) fitted a DEP slip on (much to the disgust of my OVER toting dealer) and still not changed a single screw,jet or needle. Yet my 450 RIPS. Let the motor talk (feel the force luke) The art of jetting may be lost to fool injection, but the benefits still prevail. Long live the Carb........

I've done all the mods FMF T-4 pipe W/powerbomb MXheader- extra airbox holes 12 1" on the right side, throttle stop cut, gray wire pulled out, top airbox baffle removed. I'm running 165 mj 50 pilot, needle stock 4th position and 3 1/2 turns out on the fuel screw, elevation 1500ft, Temp 70f-80f .

I'm looking for advice to get the spark plug the right color. After 25 miles with the settings above the porcelain is WHITE, the electrode as it starts out of the porcelain has a faint black line then turns to silver/gray, the tip has the same color as if it was a new plug, and the ring around where the treads are is light black.

What colors am I looking for? What jet settings would help me get there. :)

Thanks.... :D

i would base it off of how the bike is performing.. like if its back firing or if its stumbling... but how do you like the power of it after you did all those mods?? :)

The power is "GREAT". The bike is really running well. I think I'm just getting all crazy about making sure it's not running to lean. I have been hearing that it can burn hole in piston and other damages.

I just got info on some changes that I can try. I will be putting in a #170 main tonight and then check the plug for the mocha/brown color. If it then seems to rich on the top end I was told to try and move the needle clip up"needle down" to help with the problem.

I'll keep posting my findings. :)

Keep a magnifiying glass handy when checking the plug,you can see in great detail if the piston is starting to melt on top(little round shiny balls of aluminum on the electrode)sounds like you may be one of the lucky one`s,dont fiddle just for the sake of it,if its going well just keep an eye on it an` see how it goes! :)

Hi. Is it easy to do all the jetting and carb mods. Ive never done it before and am kind of nervous to take it all apart. I just bought the bike a week ago. Its obvious that you guys know what your doing with the bike so I just wanted to know if you think this is an essential thing for me to change up the carb setings. Thanks,D :)

Absolutly!!..You will notice a day and night difference with a properly tuned engine. Read from the beginning of this post, and it should give you a good idea where you should be. What kind of bike do u have?. You need to post what bike, mods, etc so the powers that be can help you. I would post them under a different thread..possibly larryco and taffy jetting questions!

Good luck!

:):D

JD....Would you mind posting the final jetting specs from your WR when you got rid of it. Would very much like to replicate your setup and call it good. I currently have my 00 setup as follows....WR timing,stock exhaust w/GYT-R insert PJ45(PAJ75),OBDVP@#5,MJ170(MAJ200),SJ65 & BK mod @ 0.3 sec. Think this is close but would like to emulate your old setup. Also am interested in knowing what you feel the stroke for the AP should measure and what points to measure from? Thanks in advance for your input. :)

The power is "GREAT". The bike is really running well. I think I'm just getting all crazy about making sure it's not running to lean. I have been hearing that it can burn hole in piston and other damages.

I just got info on some changes that I can try. I will be putting in a #170 main tonight and then check the plug for the mocha/brown color. If it then seems to rich on the top end I was told to try and move the needle clip up"needle down" to help with the problem.

I'll keep posting my findings. :)

If it isn't popping it probably isn't lean.

170 main 45 pilot seems to work good for me.

Don't forget to get rid of the stock plug, replace with either NGK Platinum or iridium.

JD - I recently installed your kit - I am not a jetting expert but here's whats happening. No problem with Idle, 1st & 2nd gear wheelies easily but just starts to pop at rev limit, 3-5 low power and popping like crazy. My carb is stock with the following exceptions:

Blue Needle - clip #3

Mj 170

MN Sea Level.

I have done all mods and added full Big Gun exhaust system. Bike had much stronger top end prior to me messing with carb and pipe. I was thinking about leaning out MJ to 165 or 160. Should I raise or lower clip and/or try red needle?

Suggestions???

I have an 03 WR450 and I too am having problems on the low end untill the RPM's get up, I am also having problems at the top end of each gear cutting out, I have uncorked it 100% (I'm in Utah, no one here to care about noise) put in the YZ stop and have not cut the grey wire yet not the air box. I'm at 4300ft and ride between 4000 and 5500, I thought it was the spark plug but I was told I needed to change my jets from stock but not sure where to go from here, can anyone help ???

Cutting out wide open is usually a sign of too rich a main jet. It is getting colder now so you may be OK in a few weeks. Next spring you will need to rejet leaner on the main and needle. :)

ya go to atleast a 48 pilot maybe even try a 50 then play with the air screw try running it around 1 1/2 turns out

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