250-500cc Where Should I Buy Jets

Not sure if my bike is jet correctly. 2009 WR250. It seems ok but I'm no expert.

When I go to ring it out in 3rd -5th gears it kind of dies out a little. Starts easily with one or two kicks.

Found this article on carbs and jetting. http://www.kenoconnorracing.com/Carburetor jetting.html
Says to buy a few each way of what's in the bike and then test.

Where does everybody buy jets? At a shop? Dealer? Online?

I have a Keihin PWK. Jetting below.


Main - 175

Pilot - 42

Slide - 7

Needle has red top. Couldn't find any other markings.

Clip is in the 2nd from top slot which is the 4th up from the bottom most position.

Bought bike used, might be a JD needle.

Thanks
Mike
Ocean County, NJ

Oh yeah, brand new, barely used FMF Qstealth silencer.

Mix is Interceptor at 50:1.

I don't ride the bike very often.

Thanks
Mike

I just read pvdukes how-to-jet thread. Much better than the other article.

I have two probably dumb questions, though.

1. What happens when the bike bogs?
2. What happens if the bike acts blubbery?

I don't mean lean and rich, but how does the bike actually behave in each condition.

Thanks

the bog sometimes feels like the brakes are being applied, where the bike loses power but it still feels somewhat smooth..bogging and being lean is also associated with a hanging idle and surging.
the blubbering rich condition also shows up as "four stroking", where it misses and hesitates, throughout the rpm range. sometimes just a certain rpm range. four stroking is when the engine mostly fires every four rotations of the crank, instead of every two like a proper two stroke.

Thanks, I think I get that.

Since my condition only occurs at what I think is 3/4 to full throttle should I just adjust the main jet?

yes, what do you feel it does? any more info on what the bike is doing

I twist the throttle but it pretty much stops accelerating. Feels like I twist but the bike doesn't react.

The no reacting part is when it's screaming on the pipe.

Soubds like you need another gear, does it take off after the no reactionor just do nothing.

Does nothing. I have to switch gears to make anything happen.

check your power valve linkage

Thanks guys. Talked with owner of local shop tonight. Showed him the plug. Tip is black. He said that looked rich.

Based on my description of bike's operation he said I should check the power valve linkage to make sure it's opening completely. I'll do that tomorrow or next day.

He also said a quick test he does in my situation is to turn out the air screw to like 3 full turns. Let in more air. If it's rich now than letting in more air should have it run better.

I did buy 2 smaller main jets which I'll try after checking power valve. Think I'll try air screw trick, also.

Dangerous to judge jetting just by the plug. Plug could be black from a rich pilot jet since you aren't really staying on the main much. Highly recommend checking the power valve before going leaner on the main.

Cool thanks will do.

Will it be obvious how far the power valve should be opening?

So I ran the bike and watched the power valve move when I revved the engine. It seemed to move through its entire range of motion. I'm talking about the part with the teeth facing the rear of the bike.

I just did it while standing still in the driveway. Had to go to flag football practice with son some couldn't ride the bike.

I think tomorrow or next day I'll try the air screw method. Depending on how that goes I'll change the main jet to something smaller. I bought a 172 and a 170. Currently have a 175 in it.

All that I've done with mine is uncover it to watch it open. Performance is fine so haven't touched it otherwise.
Just did a quick search and lots of threads to read and all the info you could possibly need

Yeah, I've read a lot of it, too.

Unfortunately, I now have paralysis by analysis!

In agreence with NCSteve, heaps of threads on this subject but the secret to jetting is to jet the bike for the purpose. If you are riding technical, slow, singletrack stuff then you want to make sure that the jetting from zero to 1/2 throttle is spot on. In fact, any fluffiness from zero to 1/2 throttle effects the entire transition to WOT.
On my 360 with the Keihin, l played a lot of attention to the pilot and slide as well as the needle but my issues were from zero to 1/4 throttle being too rich.

You could pm Motosportz and trade it in for a Lectron??

Also, grab a notepad, mark out your grip with 1/4, 1/2, 3/4 and WOT and you should be able to determine where in the throttle range the bike is under performing. You can do a plug check but unless you have a plug reader, it's hard to see the bands, even just a visiual should give you an indication where you run rich or lean.
Airscrew plays a big factor especially elevation changes and if and when you get the jetting sorted, a 1/4 turn here or there is enough to get the bike running right for the elevation changes.
In terms of setting the idle, start the bike, warm it up and then screw the idle adjustment until the bike barely stalls, then screw it out and it should reach a point where the bike starts to rev higher then tapers off, this the the max idle , write it down.

Thanks for the guidance. I do need to do the throttle marking.

I feel like I'm in good shape from the bottom to 1/2 or 3/4 throttle.

We ride tight trails but then lots of fire roads and also asphalt when doing dual sport rides. The Hammer Run is coming up soon in south Jersey.

reeds sometimes affect that last throttle range when they are tired.
you say you are going to lean the bike on the main...is it breaking up? four stroking? if it isnt four stroking it likely isnt too rich on the main.
i tune my bikes to where they four stroke, they lean just enough to where it goes away. then i know the jetting is safe and very close. some extra power is be had by further leaning, but then the bike can become tempermental to weather.

View: https://www.youtube.com/watch?v=0wzph3hL6EE