buckaroo- I'll answer your question about high-octane fuel....the fuel itself does not "give" more power.. It burns slower, and resists combustion from heat. In high compression engines (we're talking like over 10:1 compression) the air/fuel mixture is very tightly compressed, this causes the mixture to heat up. Lower octane fuel will ignite from just this heat, NOT from the spark plug, igniting before the piston and crankshaft are in the right position for igniton. It happens too early, causing the burning fuel mixture to push back down on the piston the opposite direction since it hasnt even made it to TDC yet, causing a 'pinging' sound and of course, lost power. this is knows as 'preignition'

High-octane fuel is made to prevent this- it resist burning a little bit better so the spark plug ignites the fuel when it's supposed to, not the heat from the high compression pressures. that's why all of these high-performance engines use high-octane. They pre-ignite on low octane fuel.

so in summary-low octane fuel ignites easier, burns quicker.
high-octane ignites harder, burns slower.

If you use High-octane fuel in an engine that doesnt need it, 2 things are happening- one, you're not getting the most performance out of it, since the fuel is taking longer to burn than it should (are you going to notice? probably not) and two, there is excess fuel that didnt get burned since it resists ignition, and it creates carbon deposits in your combustion chamber. The good news is, eventually these carbon deposits will start to build up and raise, that's right, RAISE your compression ratio, and then you'll end up needing the high-octane fuel for the machine to run right. But by then the valves will get carbon shoved into them and be held open, the machine will lose power and not start. bummer.

So what you want to do is this---find the LOWEST octane fuel that your machine runs on without any pinging or preignition. That way you know you're getting the fastest burning fuel that your particular machine runs on without any problems.


I have a college degree in automotive and I'm a certified Ford/Chrysler technician at a local dealership, in case anybody was wondering.

 

Thanks for straightening things out. My old-school hear-say and old myths have been up dated to correct information. Gees, even at my age I can still learn... lol... Just like the difference between a 5 year old and a 15 year old... the 5 year old has all the questions and the 15 year old has all the answers... lol..

 

what are you riding? is it a trx450r and is it towards the lower rpms of gears? sounds like its coming from front left?... if so don't worry about it they all make them in the lower rpms i've been asking people i ride with too and mines brand new everyone says they just do that

 

i all was trying to do was give some advise from my exsperieces. i've never owned any type of powersports product that didn't require at least a minimum of 92 octane. from all my years of vocational school and college automotive courses i was taught that the higher the octain rating the more resistant it was to preignition but also a more efficient burn throughout the combustion chamber, although the octane rating has nothing to do with the speed the fuel will burn. i wouldn't recommend running something like 110 on a stock motor until you get into the 13.5:1 compression ratio. the perfect air to fuel ratio is 14.7 to 1 but if you go to lean it will run hot and more than likely cause preignition. running to rich will cause carbon build-ups but will not result in excess heat. i always jet my engines to run just a tad bit to the rich side just to be safe.


i have two years of vocational school, two and a half years of college training in the ford asset program, an associate degree in applied sciences, and three and a half years dealership exsperience leaving me a ford senior master tech in case anybody was wondering.

 

uti?

 

My 4-wheeler is a 1999 300EX and I've had it for 2 months. It ran GREAT when I first got it. It is just now starting to make this rattling noise. The noise is not constantly there only sometimes. It is there especially if the engine bogs down at all. I do run regular gas in it, not premium. It seems like I only hear the noise after I have ridden for several hours and the engine is hot.

 

i would definitely try running premium, running to low of an octane won't make it ping all the time but it would under a load. once your motor warms up it should be more apparent. find a steep hill and try to climb it in first keeping about a quarter throttle the whole way up. if it pings like crazy run a higher grade of fuel. spark knock(preignition) puts extra wear on the crank, rod, pistion, and all related bearings.