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2001 YZ250- JD Jetting Kit

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Hi everybody, just bought a JD jetting kit. Instructions are pretty straight forward but everyone's bike runs different, climate and so forth. Anyways this is my first bike so yea I'm bit of a newb but hey at least I can rip my bike apart.

After installing the jets bike is running rich, at lest it seems like it. Lots of white smoke on initial start up but it goes away after I start riding. The rpm is steady but noticeably faster now. The throttle feels much better on the high end, can over rev even more bike just feels like it wants to keep going. On the low-en however doesn't feel as crisp as the top.

Am I better switching to a leaner needle or a leaner jet? Do not want to go too lean, very bad things happen. Will rip out my plug 2mororw, im sure its black lol.

Stock:

Main Jet: 178

Pilot: 50

Needle: Stock needle with clip on #3 middle of the needle

JD Jet kit:

Main: 172

Pilot: 45

Needle: Currently the richer needle on #3 clip, theres a leaner needle as well

Climate:

Elevation: 3000ft to 3500ft above sea level

Temp: I'd say 16C to 20C, 60F to 68F for u americans

Thanx in advance, man I love dirtbiking

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white smoke is burning oil and/or coolant. As the bikes temp rises the metal expands correcting the leak in your case allowing the coolant and/or oil to cease entering the combustion chamber.

Im surprised the kit recommended the 45 pilot, you learn something every day. How does the kit recommend what needle to use?

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The kit recommends this sequence of testing.

Blue = The Richer needle

Red = The leaner needle

Blue #4, Red #4, Blue #3, Red #3, Blue #2, Red #2. The "#" is the clip position.

For some reason the kit recommends putting Red #3 for the initial install? As far as I know from reading on these forums adjusting the clip should fix the throttle for 1/8 to 1/2 throttle.

I'll try Blue #2, moving the clip up allows more fuel correct? Since the bottom of the needle is skinnier.

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Moving the clip up allows for LESS fuel. The needle is allowed to go deeper into the main oriface cutting off fuel. The lower the clip the richer.

Finding out what pilot you need is easy, finding out what main you need requires some ride time, but finding out what needle to use and what clip setting should be used IMO is hard.

How do you know when you have the right needle and clip position? Doing a 1/8th to 1/2 throttle test is pretty hard imo.

Does the manual tell you what you are looking for when adjusting the needle in terms of performance, thanks for the info!

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No it pretty much just gives recommended settings. One thing that I did notice is that I can't start my bike w/o the choke anymore. It will start but it will just cut out after like 5 sec. B\f I jetted my bike started 2nd kick, no choke everytime.

Thanx for the correction on the needle. You think I should switch the main jet b/f I switch the needles?

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No, your jetting is pretty much dialed in for now. Play with the needles and clip positions to refine it.

Whats your altitude?

I'm at 3500-4000 ft and I'm using a 170 main and a 48 pilot.

Being able to use your choke again indicates proper pilot jetting, which means that before it was too rich.

I'm thinking of putting my 45 back in just cause you got the kit and that's what it recommended.

I was trying to achieve jetting perfection, but without proper headwork (squish band) you can only get it so close.

What other main jets do you have?

Run the bike first and see what kind of spooge your getting, do a plug chop test to be sure, before you start going any more lean on the main.

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