Yes, we definitely all have our own views on the octane issue, and I'm not about to start another 'conversation' on that.
But either way, I think it's ok to assume that you are best off running premium (92 octane) in the EX, since that's what the owners manual recommends, and a little extra octane won't hurt anything. Where on the other hand, too low of octane could cause predetonation, which causes premature wear on the engine. Many people don't know what predetonation sounds like, and would ride their bike right up 'till they burn a hole through the piston. I'd much rather tell them to just take the safer rout, and spend the extra 25 cents on a tank of gas.

 

Motorhead -

I agree with you on putting higher octane in your atvs since they often do sit a while without use. That's a very good point.

I got to thinking about that, and I have a simple theory. Honda knows atvs often sit with the same gas in them for long periods. Maybe that's why they recommend 92 octane for a machine that will easily run on 87 - 89 octane. Sure would be cheaper for them to avoid warranty work on pistons with holes through them, given the degredation of octane/fuel over a period of time.

Happy Holidays,
ogre

 

That could be true. 92 octane minimum sounds pretty high for an engine that only has 9.2:1 compression, I know most V8's with that low of compression would run fine on the cheap stuff (regular unleaded). So, either Honda is playing it safe, like you said, or possibly they are running a pretty steep advance curve on the ignition.

 

In my experience, my ATV's run much better on higher octane gas. I always use at least 92. The higher (premium) gas around here is non-oxygenated, meaning no alcohol in it. My stuff just runs better on it. I mean it starts better, runs better, no missing etc, which in my opinion means more power. My 350X would spit and sputter and run like crap unless I put 92-93 octane in it. If I put 87-89 in, it would backfire, miss, die on idle; it would just run like crap. My wifes blaster was similar, but not as bad. So, all I use is the 92-93 stuff. I have never used less in my 400EX, so I don't know about that.

The octane of the gas might not be making the difference, but I think the quality of the gas is better, and that is what I think you are paying for.

 

I run 89 octane.at idle it misses sometimes, but thet could be the plug. I am gonna start using 92 octane.
RedDog400ex: How do you like your supertrapp pipe? Is it the ids2? Did you gain much more power with the pipe and filter? How does the power hold in 5th gion up hills compared to stock? Thanks