250 2006 YZ250

Y'all knew this thread was coming!

Gas question -

Had a really good rider on a 2010 ride my bike last weekend, he said he thought he heard it pinging. He asked what fuel I was running, and its premium 91, what we have here.
Went to the track today and after a few laps I started hearing it too. After a few laps of that I got super paranoid about blowing my shit up, so I pulled off and found a real nice guy named Jim that sold me a gallon of high octane. I drained my tank, and remixed it all back together. Much better.

So my question is this - the nearest place to buy high octane is 25 miles away, and it's 100 unleaded. They also sell 110 leaded.
But I have an airport (dropzone) here in my town that'll sell me 100 low lead for half the price.

Should I drive the 25 miles out of my way, or just go get the 100LL 8 miles from my house? Or is 110 leaded better?
 
You can measure the squish and send the head off with solder measurements and have it cut for the gas at the station. What you hear is detonation and it will eat your head, piston, and top of cylinder wall at head.

Fuel does not really correct these engines as well as the squish mod.

Your welcome!

There is Ken O'conner and a few other race guys that do this mod. You could have it done local if you have a guy at a machine shop close to you that knows what you need.
 
It’s the squish band. The amount of space between the head surface and the piston surface at top dead center. You will need someone to cut the head and mill it for pump gas. Common issue for the YZ 125 and 250.
If you fire up the google machine you can probably find 200 places across the US that will exchange your head for a cut one as it was a common popular mod.
Also I wouldn’t use avgas in my 2T. It’s formulated for a much different type of engine that works at very low rpm like a tractor. You can use it but not with the same success you’ll get with a VP gas. As for race gas in a whole, unless you have a complete worked motor, head shaved, ported and cut cylinder, matched cases and more then running straight race gas is a waste. I mix mine around 25% race gas (VP C-12) and 75% pump. The only reason why I run it that way is because 1: it’s a waste of money to run it 50% or more because my motor is only mildly tuned and I’m not racing at the pro level.
I benefited from the crisp throttle response and ease of jetting by using That mix.
 
I’ve heard horror stories of running Av gas in motorcycles. Not sure if it’s true, but I will never do it.
 
But now that I think of it big Dan used to run it in his scooter all the time because it was readily available, as in free, nnd I don’t think he ever reported a problem.
 
Never said it would correct the problem. I’m just saying that everyone seems to say av gas is a no no for some reason or another. But also I remember big Dan in charge of the Av gas fuel pump without any problems. Bite me YZ Doc, stick your stethoscope up your ass.:smirk:
 
Never said it would correct the problem. I’m just saying that everyone seems to say av gas is a no no for some reason or another. But also I remember big Dan in charge of the Av gas fuel pump without any problems. Bite me YZ Doc, stick a camera up your ass.:smirk:
They did, and it was clear except for diverticulitis. Would you like to see a photo? They are from Wednesday. :banana:Sides, I wasn't talking to your sweet :moon:, look at my first post as I reiterated what I said. I know guys that run Avgas, but it's for "other" reasons, and after the swish band was fixed. I was talking to Opie, and we shall see 10 pages before the swish gets measured, and it happens. I'm not talking about the squish it will cost to correct. So lick my fuzzy nuts timoyz, I hear they taste great, and are less filling. :P:smirk:

BTW, hows the shoulder? Still hurt? Doctor says, "stop master bating, it will heal quicker." :poke:
 
But now that I think of it big Dan used to run it in his scooter all the time because it was readily available, as in free, nnd I don’t think he ever reported a problem.
You can run it. Just not a great gas choice for a high revving 2t. I’ve never heard anybody doing damage though.


Hmmm, I wonder?

:confused:

YZ DOC is :thinking:

Nope!!! Like I said, fuel doesn't correct the problem.

:bonk:

Head needs to be cut. It’s the only fix for the 250. And I think it’s like $40, right?
 
I'm in love with everything about this bike, she ran great all day today, no pinging. Yesterday I mixed 1 gallon high-octane to about 3.5 gallons 91.
 
You can run it. Just not a great gas choice for a high revving 2t. I’ve never heard anybody doing damage though.
Head needs to be cut. It’s the only fix for the 250. And I think it’s like $40, right?
Just about if you can do it local. Add shipping of 14 for both directions (flat rate box)

You know you still need to do the head work right?
No way, just do what John \/ said down there.

keep it on the pipe you’ll be fine.
That fixes everything. :loco:

I'm in love with everything about this bike, she ran great all day today, no pinging. Yesterday I mixed 1 gallon high-octane to about 3.5 gallons 91.
For an average of 92.3. :deadhorse:
 
Do I only need to do head work if I want to run pump gas?
I'd rather drive up the road and buy the good stuff than take it apart then be down for 2 weeks...
 
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