What gas should be used in a scrambler 400 4x4 with a stock head, and dg pipe, 87 or 91 octane?

 

I would always use the higher octane in anything that you want better performance out of. The octane rating is telling you how many particles combust per 100 so the higher rating would mean better performance. Although some vehicles do not require a high octane to perform better. The general rule I go with is use the highest octane like 92 or 93 for atvs, dirt bikes, motorcycles, etc... use the 87 for your car unless otherwise specified. Just my opinion on that but, the fact that is stated is true.

 

Jump, you are a little off base on the octane thing. Higher numbers do not translate into more performance, unless your engine is designed to use it. Octane is the resistance to ignition,or more precisely, to preignition (pinging) in the combustion chamber. More octane makes the fuel burn slower, so that in a high compression motor, the flame front is uniform, and not igniting randomly, causing the ping you hear from the sound waves impact on your engine cylinder from the random,premature ignition.
In a stock, low compression engine, use the lowest octane that will burn without pinging, and you will see better performance. High octane in a stock motor may actually lower performance and cause engine deposites from incomplete burning, and cost a lot more in the process. For a stock ATV, 89 octane would be fine, I am running a 10.25 to 1 piston and have had no problems with 89 so far. Anything above that, and I would run the 92.

 

95wolv
You are correct. Actually most people think that higer octane is more powerfull and will enhance performance. Since it costs more, it must be better. This is totally untrue. If the manufacturer says to use regular (87 octane) then use it. Click on the link below, learn a little and stop wasting your money.

Octane myths

 

I'll third that. Love to see the guys fill up their stock or almost stock bikes with racing fuel so they will run better. They run so rich it's really funny.

 

I heard the info on the octane rating that I stated on a show about oil and how gas is made but, hey maybe I shouldn't believe everything I see on T.V. right? The other point was just my opinion.

 

All higher octane does is resist pre-ignition. It doesn't burn faster or hotter. It allows you to run higher compression and/or more timing advance, if you're modding your machine. Generally, run what the owners manual calls for.[img]i/expressions/face-icon-small-smile.gif[/img]