Jetting on 250X help Please

[tkatka70]

Im planning on getting a WB E series PRO MEG slip on for my 1987 250X. I live in Central Minnesota and was wondering how many discs should i run and what my jetting should be. I want to know what size of jets i should get so i dont waste my money and by a whole jet kit then i will have a bunch of useless Jets laying around. So what should my jetting be. ANd what what would my jetting be if i ran a K&N filter. Thanks for the help. Im not sure of my elevation but i live in Central MN.

[Rastus]

It should come with 12 discs. When I got mine it said it runs the best on 12 discs.


It's going to be hard tell exactly what jet you will need. What jetting do you already have?

[tkatka70]

stock jetting i assume. So run it with 12 disks

[2fastandfurious]

I put a aftermarket pipe on mine and rode around for about 3 months. I put the stock pipe on and I had better performance. I think the sound made me think i was doing better. LOL! Is it possible for the quad to run WORSE with a aftermarket and no carb work?

[Rastus]

Yes, if you didn't jet properly, or didn't jet it at all, it's bound not to run good.


Yes, WB recommends 12 discs. That's just a base though, you can add or subtract discs for a diffrent powerband.


I think my quad is jetted at 130 main...Been awhile since I've done carb work. It's not stock, so I can't tell you guys what jet to use.

My suggestion would be get a bunch of jets, it will save you time over all. FInd out what jetting a stock X has, and get sizes bigger, and get some spark plugs.

WIth the new pipe, and Filter,run it reving a good bit to make sure your testing the jetting of the Main jet, not the others.

Let it cool, then check your spark plug.

It it's white...then it's too lean, if it's black it's rich. Each time trya diffrent jet, and put a new plug in.Do this till you get a light brown color on the spark plug.

Remember, Main jets control gas flow from 3/4 to full throttle, so don't idle it when your testing.


Then you can move on to testing/jetting your other points.
I dunno the other places in jetting, I forget,lol.

I believe a Pilot jet controls idle to 1/4 throttle.
Then the needle with the clip controls 1/4 to 3/4 throttle.

If I'm wrong, I'm sure someone will correct me.

[wilkin250r]

I always jetted my carb with a hand-held tempurature with a probe, and measured exhaust tempurature. You can get them on ebay, similiar to Item # 3104350060

Get a base reading with stock components.

Take another reading after adding aftermarket pipe, ect...

Lean=hot

your tempurature should be a little hotter, more power produces more heat. It's the best method next to gas emmission analysis.

[tkatka70]

what does a stock 250X got for jetting.

ALso when you get the White Brothers Pro meg exhaust does it come with instructions on how to jet in and does it come with a few jets.

[tkatka70]

bump

[tkatka70]

can i get some help please

[Hals250x]

Stock jetting is 122 main and 38 pilot. Run the pipe with at least 12 discs. Up your main to 125-128. If you install a K&N, you'll probably need to up the main to 128-130.

[rap169]

mine had a 125 stock main. i put a RCM Pipe and silencer and removed my air box lid , then changed my main to a 135. It seemed too big in my mind, but it ran better with the 135 compared to the 132. I live in PA so im not sure if your altitude is different.

[tkatka70]

do i need to change the pilot jet. Also do i need to move the clip on the neddle. I should be getting my pipe any day now thanks guys for helping me out. Stock main is a 125 so i bought a 130 and a 132 im wainting for my pipe now and my uni air filter.

[rap169]

Now that u mention that, i did change me setting on the needle. I messesd with the carb alot and its tough to get it right without a dyno. U can get ti close though. If i remember correctly, i think i moved the clip down one notch on the needle. I sugest you buy a pack of jets for like 20-30 bucks. The one i bout had jets from 130-140. I started with the 140 and tried it. Then i kept changing them out all the way down to the 132. Found it ran better with the 135 so i put that one back in. I never messed with the slow jet. couldnt help you there. I think i want to try an oxygen sensor next with a air/fuel ratio gauge. Im just worring about it obstructing air flow, and having a hard time to get it right.