what type of gas should i use i hear diffent opinions

premium or regular or super unleaded....

regular... 87 octane.

http://www.ninjette.org/forums/showthread.php?t=15904

Use the cheapest gas available. I recommend getting a bigger fuel filter than putting in anything above 87 octane gasoline. Take out the inline fuel filter and replace it with one for lawn mowers like this one:

http://www.hardwarestore.com/media/product/283275_front200.jpg

Ok, I hear this question time and time again, and I just really want to educate people on this.

Fuel as we all know comes in different octane levels. Why are there different levels? To accommodate for varying cylinder compression ratios.

A 250 was designed for 87 octane. If you run less, you are leaving your self open for detonation which can cause engine damage. Fire off the mixture prematurely due to heat, and your compression stroke turns into a power stroke, trying to force the piston back down, when it needs to continue up. Bye bye piston.

Now people for some reason think that running a higher level octane yields a higher level of performance, or it is a cleaner gas.

For the most part, this is false. Granted, some gasoline's put little additives into the gas for the higher level grades, but it does not yield a gain in performance. A bike like ours (or cars for that matter) which is designed to run 87 does not like anything else. The higher level octane, the slower the burn. The slower burn is typically compensated by a higher compression ratio to offset the burn rate.

Add high octane to an engine designed for 87 and you will lose performance. The gas will not burn as quickly or efficiently, thus causing a loss of power. So if you want to lose a little HP, add some higher octane fuel. The losses of not running the recommended gasoline in an engine far outweigh the possible gains (if any).

Typical fuel system treatments treat a certain amount of gas. Mathematically figure out the conversion for our tanks, and add that every 3k miles or so. I think that will be better in the long run than running a higher octane.

Run the recommended fuel. Your pocketbook and your bike will thank you

Apex - I'm with you 99%, and your overall recommendation is spot-on, but there's just one quibble. Higher octane fuel doesn't necessarily burn slower. Or burn faster. The only thing the octane measure reliably correlates to is the fuel's resistance to ignition due to pressure. Once it ignites, it may burn slower, faster, or exactly the same as fuel that has a lower octane rating.

Mark is spot on. Just for grins and giggles, What is more flammable--87 Octane or 93 Octane? The answer is- 87. Our bikes are designed for 87--so are most of our cages--except for the Corvette (as an example) I really don`t know how true this is, but I was told by a pretty reputable mechanic that using Premium Gas--93 Octane in a car or bike designed for 87 Octane, will cook your catalytic converter after some time because it gets an overdose of unburned fuel. After a while you end up getting a smell out of the exhaust like rotten eggs (Hydrogen Sulfide--H2S) He says that the H2S smell is a sign that the converter is dying.

it should be noted that if you change the the cam timing, and or igntion timing,ontop of intake/exhuast and carb mods, should be able to get more power out of higher octane fuel. however you need to dyno tune it with a wideband O2 sensor, and other things. this also goes for just about any motor.

but unless your racing, and have money to burn i would suggest against this ;)