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Idle speed On YZ250

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Just got my brand new 2014 YZ250 home, Love the bike a few small things i'll have to do like cut down the seat, its way to high for me and the suspension seems really stiff.

 

But the bike will not idle, only with the choke on full, the Dealer had half a tank of gas out it in it so i decided to fill it up with 94 octane mixed 30:1 still does not idle, I added a little more oil to get around 20:1 shes smoking a lot and runs fine has lots of torque but will not idle.

 

I looked in the manual and it seems like I have to turn the plastic black screw with the spring on it "in" or clockwise I turned it about 3 times and the idle did not change so i'm not sure what to do anymore. I had an RM125 and it ran perfect from day one and is still going strong

 

Suggestions please.

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Just got my brand new 2014 YZ250 home, Love the bike a few small things i'll have to do like cut down the seat, its way to high for me and the suspension seems really stiff.

 

But the bike will not idle, only with the choke on full, the Dealer had half a tank of gas out it in it so i decided to fill it up with 94 octane mixed 30:1 still does not idle, I added a little more oil to get around 20:1 shes smoking a lot and runs fine has lots of torque but will not idle.

 

I looked in the manual and it seems like I have to turn the plastic black screw with the spring on it "in" or clockwise I turned it about 3 times and the idle did not change so i'm not sure what to do anymore. I had an RM125 and it ran perfect from day one and is still going strong

 

Suggestions please.

You didn't happen to dump oil directly into your tank, did you? If so, you need to drain it out or find a creative way to mix it in the tank then drain your carb...

 

 

but if you mixed it in a can...then you're allowed to turn your idle screw all the way in...gently...and with the bike running...if it still doesn't idle, tinker with your mixture screw in and out, after that it gets a little more involved....draining your carb, cleaning your pilot....

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I'll try turning in about 4-5 turns and see what happens, I mixed 20L worth gas 30:1 (using my mixing ) in a jerry can, then added about 5L to the bike or less, after a while i added just a little extra oil in the tank of the bike and shook it best i could, the thing vibrates a lot more than my 125!! I've since burnt all that gas out.

 

The bike runs smooth with way more torque then I imagined, even going as slow as possible giver' half throttle in 1st or 2nd and if i got traction the front tire will lift. It just don't idle.

 

I added a little more oil to my remaining 15L I  figured i'd mix the first few runs heavy then lighten up a little.

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I'll see how it idles after a few tanks, weird thing is my buddy and I both bought bikes as a package deal, I got a YZ250 for $7600 and he got a KTM 250SX 8300 his bike idles perfect! just like TTR230 or YZ450F

 

The cheaper YZ I could get the new Rekluse 3.0 kit and FMF Knarly pipe/silencer Combo. I have blue and orange Troy lee gear, so I could even grab an orange sprocket and bars. I'll be at the same price as the KTM, I also got a topend rebuild + updated plastics with mine that he didn't

Edited by Adamadam

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Try a new plug. Of course first try adjusting the idle screw and air screw. If no joy with any of that then start thinking about a smaller (48 ) pilot jet, and also measuring the squish clearance because yam get it wrong often and too wide means jetting issues including poor idling.

Edited by numroe

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Try a new plug. Of course first try adjusting the idle screw and air screw. If no joy with any of that then start thinking about a smaller (48 ) pilot jet, and also measuring the squish clearance because yam get it wrong often and too wide means jetting issues including poor idling.

Numroe just gave you the answer. They are rich from the factory. They need to be leaned out slightly on the bottom. Adding oil is not the answer... mix up some fresh 30:1 and turn the air screw out one click (1/8 turn) at a time

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I'm pretty sure its rich, The bike smokes a lot maybe 250's smoke way more than 125's.

 

Does anyone use Iridium plugs? I switched to iridium plugs on my 125 and went 2 years now on the same plug, it use to fowl a lot of BR9ECS plugs.

 

Also would the idle have anything to do with how hard this bike is to start? Holy sometimes I can't start it, thats some of the reason I got a 2 stroke is becase everyone i'e seen or rode starts first kick usually.

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Adam I to have a 2014 u have to turn the idle screw in quite a bit to make it idle. Not to much though or it will rev to the moon when you start it with the choke on. I recommend using ngk br9eg racing plug

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Your 250 shouldn't smoke more than a 125. Just get your jetting right, and let the oil mix ratio match the RPMs you mostly ride at.

 

Warm or hot start should be one kick every time.

 

They can sometimes be hard to start if left to sit for a while with old fuel mix in the carb, or if the crank case has an excessive pool of oil in it, I suspect because this makes it easier to foul or semi-foul a plug, or maybe some fuels go stale faster than others.

 

For cold starts, consider trying a different brand of oil and fuel. Fresh fuel.

 

If it smokes a lot, then try the air screw (out), and if that doesn't help then go leaner on the pilot jet, and if that's not enough of a fix, then consider the leaner #8 slide.

 

My motor does not idle great for a long time, as a 250 or 295 it's the same, but with the leaner pilot it sure became a lot better!

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i have a few jets or whatever in my rebuild kit, I've never changed a pilot on anything before, usually just a jet, most snowmobiles i've owned had a power jet system.

 

I ordered a BR8EIX it wasn't much more than the the stock plug I was going to have a look at my plug today but it started raining. I don't have a garage yet, it burnt down and i'm still waiting to get a new one built.

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Just FYI, you do not have to remove the carb to replace either the main or pilot jets.

 

To remove the these two jets:
 

- remove fuel tank, to get some slack in the throttle cable.

- remove the counter sprocket chain cover, to allow access to the carb.

- Loosen the carb boots and rotate the carb so the bowl drain plug is facing outward.

- Remove drain plug.

- Remove pilot jet with a suitable flat blade screw driver which nicely fits into the hole in front of the main jet.

- Remove main jet with a 6mm hex socket. The main jet is the obvious brass thing in the middle.

Edited by numroe

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Even if he is riding MX or holding the bike wide open for extended periods on fire roads 20:1 is a very heavy ratio. The fastest pro's back in the day ran about 28:1 give or take and those were heavily modded motors that were held open for an entire moto.

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Its just for break in, I was told break in is 15:1 once its broke in i'm only going to use 40:1 like i have on every premix toy i've owned.

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15:1 is way too rich. Try fresh gas at 40 or 50:1. Drain all the old mix out. Set your air screw at 1 1/2 to 2 turns out. You should be able to get it to idle with the idle speed screw. If it is still too rich check the needle position. I have seen dealers set it rich for break in. Check your manual. Clip lower on the needle is rich, higher is lean. Needle is for part throttle adjustment, but does affect idle some.

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You don't need to change your ratio for break in. That is 100% myth. Half of those guys at the dealer have never even thrown a leg over a bike let alone know what they are talking about in regards to setting one up or tuning it.

 

Pick the ratio you want to run, empty your tank and fill it up with said premix ratio. Ride it without hitting the power band (don't go over about 1/2 throttle) for about 10-20 mins or so, look the bike over well looking for any problems such as air leaks etc., if everything checks out go rip the crap out of it. 

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