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Yz250 question

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Hi guys I'm not good on timing or jetting.

Anyone tell me how I know if my bike is pinging. Don't even know what this means.

I'm a inter rider I do push hard at times but want to be faster. I don't get much spooge and I feel that 3/4 to WOT the bike seems flat but still pulls but not as good as 1/4 to 3/4 throttle

Got a OEM jet kit on the way. Because I don't know when it was done

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If it's due for a rebuild it could be losing power

Pull ur plug out and check if its black your too rich ... It's sposed to be tan ... If its to white it's lean to my understanding

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If it is pinging you should know. If It sounds like a rock is bouncing around with the piston when you are coming on to the powerband you are pinging. Or sometimes it kind of stumbles too.

Edited by Hutch1

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Which year of YZ250?

 

Post a sound grab of your bike under acceleration/one lap and we'll let you know if you're pinging. Sounds like empty spray paint can during roll-on acceleration. FYI, these bikes are pretty flat on top compared to a 250F or 125 2-stroke and 3/4 to WOT there's a lot less torque especially in 4th and 5th gears.

 

Post a picture of your plug color after doing a plug-chop. Remove the carburettor, unscrew the float bowl, unscrew the pilot and main jets and let us know the numbers. Remove the carburettor needle and let us know what needle you have. Let us know what gas you're running, and what elevation you're at. Post an overall pic of the bike.

 

Read the FAQ (Frequently Asked Questions) on the YZ 2-stroke page.

 

We'll go from there. We'll hopefully fix your detonation before your piston breaks and ruins your engine.

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Thanks for the reply guys. To wot u have said it ain't pinging. I did foul the plug at one meeting be that was because the air screw was only 1/2 a turn out. God knows why.

It's always run very well just wanted know what pinging was.

image.jpg

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Suggest to run some race gas (eg VP or Sunoco 110 octane) mixed with highest octane pump gas you can find just to be on the safe side, and replace the topend if you're not sure of the actual hours.

Get timing and jetting setup as soon as possible so that your engine is not ruined (like I did back in 2005 when I first owned a YZ250). These are awesome bikes when setup correctly.

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Suggest to run some race gas (eg VP or Sunoco 110 octane) mixed with highest octane pump gas you can find just to be on the safe side, and replace the topend if you're not sure of the actual hours.

Get timing and jetting setup as soon as possible so that your engine is not ruined (like I did back in 2005 when I first owned a YZ250). These are awesome bikes when setup correctly.

Yes plan on doing the timing just need a dial

And here in the uk the lowest octane fuel is 95. I always get 98 or 99 no where sells 110 and I ain't paying crazy money for fuel.

I did the top end 8hrs ago so that's fine used a wossner piston.

Only thing I need do is the jets and timing.

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Oh and just found 102 octaine pump fuel will the bike run better with it?

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If you run more octane than needed, your bike makes less power. Not enough and it can detonate. You should be fine if the compression ratio is stock.

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Not sure Europe uses the same octane rating system as the U.S. does.  I don't remember the details but you can't compare quite that easily.

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In the U.S. we use R+M/2. Personally I like looking at the motor octane when I pick my fuel. For example vp 110 and sonoco 110 will have different motor octane. If I remember right the vp110 has a motor octane of 104-105 and the sonoco has a motor octane of 106. Premium fuel there, the octane numbers will be higher than here if that makes sense.

 

From what I found on my 250 and with the 295 kit, the better the fuel the cooler it runs. It also seemed more consistent and easier to jet. My 295 on the pump fuel head and stock timing loves a 50/50 mix of premium and race fuel.

Edited by highmark00700
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In the U.S. we use R+M/2. Personally I like looking at the motor octane when I pick my fuel. For example vp 110 and sonoco 110 will have different motor octane. If I remember right the vp110 has a motor octane of 104-105 and the sonoco has a motor octane of 106. Premium fuel there, the octane numbers will be higher than here if that makes sense.

 

From what I found on my 250 and with the 295 kit, the better the fuel the cooler it runs. It also seemed more consistent and easier to jet. My 295 on the pump fuel head and stock timing loves a 50/50 mix of premium and race fuel.

Thanks for the info mate

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