But it will not run cooler on premium if you're not experiencing problems with detonation or preignition. These is no advantage to running premium if you're not experiencing these conditions.

 

I have a background in chemistry. I'm not involved in the petrochemical industry but one thing I can tell you though is that the Octane Rating of gasoline does not measure the level or amount of octane in gasoline. It is actually a comparison. It compares the flame front propagation rate (how fast the fuel burns) of gasoline blends to that of pure isooctane. In other words isooctane burns relatively slowly and steadily. You want to create heat to expand the air which then exerts pressure on the piston. When gasoline burns to fast it explodes or detonates this is of course undesirable as it can cause mechanical damage to the piston. Pure isooctane has a rating of 100 this is the measurement standard that the speed of fuel burning is measured against. Unfortunately we don't have the equipment here to measure that parameter or I'd help you out.

 

Thanks! Glad to have so many diverse people on here, so much knowledge.

 

I'm still liking the lightened wallet thing...

 

I just added a little Shell 95 yesterday. They've got some fancy name for it, but I don't remember what it's called, but it's the only premium they had. I'm just happy to be using quality gas

With at least a 11:1 CR and an a/f ration that's probably on the lean side a tad, I don't mind a little insurance

 

hi guys interesting thread. i have a klx 250 and a yz 250 2 stroke motor cross bike. in the yz i would not run anything under 98. it burns slower. if i ran it on less, when it had been ruining for a while and the motor is hot the fuel would burn instantly when the spark plug went off. and because your motor is designed so the fuel burns slowly this would screw up the piston and cause the bike to seize. your bike is designed so the spark plug fires when the piston is at about top dead center and the fuel burns away from the spark plug slowly and applies force to the piston as it starts to move down. now if it ignites instantly with the spark plug and the heat of every thing, then a huge amount of force is applied to the piston when it is not moving down. this is what causes the pinging sound of a motor when its detonating. its all that force trying to escape and it causes the cylinder to vibrate. your bike will run a little bit like this then it will seize or/and blow a hole in the piston. so in the case of the klx if it is tuned right then 91 would be fine for just general riding. i run mine on 95 as i ride mine in sand which means i ride the bike at high revs for longer and for long trips on open roads at 100 + kmh so the engine runs hot so just to be safe i run it on 95. as far as i see it there is no harm in ruining higher but could do a lot of damage going lower.

 

On the husky forums it was recommended to add a splash of race fuel to the tank to bring up the performance. I'm a believer as it starts better and runs cleaner. After installing the big bore on the klx250s I thought the same thing add a bit to see if it helps. I didn't care that the cost vp 110 is 7.95 a gal out of the pump. I couldn't tell any performance benefit other than the header pipe not turning different colors. Premium unleaded is 4.19 .20 cents more than regular, so a whole .60 cents more per tank full. But running regular throttle response was lacking and not as peppy. So I figured that I want all the performance it can muster, so the extra .60 cents is no big deal. I'd like all 26-29 hp to be available when I need it.

Taxonomy when I took the klx & husky to imperial valley and it was 104 outside I know both of the bikes appreciated running on premium/race gas to help keep cool. And your expertise on the internet is appreciated.

 

It does run better on 91. More snap and crisp power. 87 can be a bit sluggish and doesn't always like full throttle in high gear. Bu thats why you run 91, prevent detonation under load

 

Add sand, rocks, whoops and some slow going..... Yeah I'm gonna run regular riggghhhhtttt.

 

Show me the... dyno facts! I'll believe it when I see it.