which pump gas is better for my ex ?

[HiperEX]

i was just wondering if this would help anything to the motor for longer live if i ran premium or the regualar? ive been running regualar for as long as i can remeber so anythin inputs on this?

[Ryan]

It depends really. On my quad if I run 87 it runs kinda crappy so I usaully put in 92. On your 300ex I would run 92. In the long run you might get alittle more out of your engine. by the way, get Sunoco gas if you can.

[TRX300X]

Actually you want to run as low of an octane as possible. Your engine runs hotter when you run a higher octance and heat is your enemy. The cooler your engine runs the more life you will get out of it. Most stock engines will run on just regular 87 octane unless otherwise stated. Once you get into big bores and high compression then you need to run a higher octane.

[RideSportrax]

Originally posted by TRX300X
Actually you want to run as low of an octane as possible. Your engine runs hotter when you run a higher octance and heat is your enemy. The cooler your engine runs the more life you will get out of it. Most stock engines will run on just regular 87 octane unless otherwise stated. Once you get into big bores and high compression then you need to run a higher octane.

This is the dumbest thing I have ever heard. :huh

[Steve-o 400EX]

Originally posted by TRX300X
Actually you want to run as low of an octane as possible. Your engine runs hotter when you run a higher octance and heat is your enemy. The cooler your engine runs the more life you will get out of it. Most stock engines will run on just regular 87 octane unless otherwise stated. Once you get into big bores and high compression then you need to run a higher octane.

Who the **** told u that?:huh

It says right in the owners manual to run no less than 92 octane. I use sunoco 94 and my machine loves it and it doesnt run hot.
Please, if ur gunna post, dont give someone wrong information.:rolleyes:

[440ex kid]

Not that I'm makin fun of you TRX300X, but high octane doesnt burn as well (or needs higher temperature to burn completely or sumthin like that). So that leaves more unburned gas to evaporate on the piston and cool it down.

Anyways, I run 93 octane but 87 works fine. I wouldnt use BP because they add to much detergent and other additives.

[TRX300X]

I'm not posting any wrong information here. Lower octane gas burns at a lower temperature. 93 octane gass will burn hotter then 87 octane gas so if you run 93 octane the gas burns hotter so your engine runs hotter. I'm not here to say your engine will overheat if you run 110 octane on a stock engine but what I am here to say is if you want the most horsepower you run as low of an octane as possible in order to keep your engine temp down. It's pointless to run a higher grade gasoline then necessary, you're just throwing your money away. I'm a mechanic for a living trust me I know what I'm talking about.

[440ex kid]

Ok I see where you comin from now. My friends 440 (13:1 compression) runs hot on 110 octane. So what your sayin is we should run lower octane to lower the temp?

[TRX300X]

Depending on what kind of cam you're running you might be able to get away with a lower octane yes and your engine would run a few degrees cooler. If that doesn't help enough a large capacity oil tank or an oil cooler might be something you'd want to look into. I run an oil cooler on my X and it runs considerably cooler. Also jetting plays a role, if your jetting is too lean your engine will run hot also. Sometimes it doesn't hurt to fatten up the jetting just a hair or two just so long as your engine doesnt load up or foul plugs.

[TRX300X]

Depending on what cam you're running yes you can get away with running a lower octane. It's not going to make a HUGE difference but a difference none the less, another thing to look into would be a large capicity oil tank or even an oil cooler. Also if your jetting is lean your engine will run hot too so it wouldnt be a bad idea to fatten it up just a hair or two. Not too much so you're loading up your engine and bogging down or fouling plugs but there's always a little leway in jetting.

[TRX300X]

sorry double post.... the first one didnt show up untill just now

[Chanman420q]

But doesnt running a higher octane give u better performace, i had a blaster and i noticed it was much snappier with 94 octane then 87. And the blaster was stock motor wise

[TRX300X]

A lot of 2 strokes require that you run a higher grade gasoline. I don't know off the top of my head what a blaster requires as far as octane rating. Generally all 2 stroke engines I've had I've run premium in them except for outboard motors. Outboards aren't that high strung. In so far as 4 strokes almost every stock engine I've encountered runs on 87 just fine. I've been in and out of the X and EX engine through and through and I know for a fact that you can get away with running 87 octane no problem on a stock engine.

[darrell43031]

if you run cam 2 in your stock bike will it hurt anything or make anything go wrong?

[crashinmatt]

wow, ive always been told the higher the octane the lower the temp. this is the first ive ever been told that lower octane runs cooler.

[jaspurx]

i wish you could buy the old- days- style leaded gas. if i remember correctly , it was higher octane than todays premium! and suposedly , it ran cooler too!

[440ex kid]

You could run Cam 2 on stock compression. It would prolly run like crap though. Heck I doubt it would even burn cuz isnt Cam 2 like 110 octane?

[TRX300X]

Race gas would burn on stock compression. It might start a little harder when it's cold. I'd run a hotter plug. In so far as leaded gas I have no idea. I know Mickey Dunlap runs lead with some of his engines, I have no experience with this however so I can't speak for that. The lead doesn't burn does it? The only reason I can see running lead is because the lead would have an added cooling property to the fuel since it may not burn.

[optikid123]

Originally posted by TRX300X
Actually you want to run as low of an octane as possible. Your engine runs hotter when you run a higher octance and heat is your enemy. The cooler your engine runs the more life you will get out of it. Most stock engines will run on just regular 87 octane unless otherwise stated. Once you get into big bores and high compression then you need to run a higher octane.

i wish i had a BS meter to post will someone do it for me

higher octane burns cooler why? because when higher octane gas burns it take longer and is not as much of an explotion as lower octane high octane gas burns smoother while lower is just more of a bang. so with higher octane there is a lower engine temp which is why engines run better on high octane fuel besides the compression ratio.

[TRX300X]

How does a Diesel engine run with no spark plug? It compresses the air fuel mixture. Gasoline engines compress the air fuel mixture. What happens when you compress an air fuel mixture? It heats up and becomes volitile like in a diesel engine and ignites unless it has glow plugs and that helps out some. You're right about how the lower octane gas burns all at once where as a higher octane gas burns more slowly. But the longer the burn the more heat it gerates too. If you take a lighter and make it spark what burns your finger quicker the spark from the stones or the actual flame? Get my point? The hotter the fuel burns the more heat it generates thus the higher engine temp.

[RideSportrax]

Hey Guys
No offense, but theres a lot of bulls*it floating around. High Octane fuel does not burn faster or slower. It does not burn cooler or hotter than low octane. Cam 2 will run fine on stock compression, but is overkill. The flame front is the same on lower octane and higher octane fuels. Understand? Just read this and learn from it, im not flaming anybody. Ok?
Higher Octane fuels. The benefits of high octane fuels is that the fuel will resist detonation or pre ignition on an engine with higher compression. For example, if you started runnimg a big bore 400 ex on 12.5:1 compression ratio, you need a higher octane race gas. You are not going to get more power, but the engine will not detonate or pre ignite. Detonation, for those that don't know, is one of the worst things for an engine. There are many ways that detonation can occur, for example, a hot running engine with lots of compression running too low an octane. The fresh charge of fuel will enter the cylinder, and upon hitting for example the overheated piston crown, the fuel ignites before the sparkplug has a chance to ignite it at the proper time. Now, this is very harmful in an engine. It can be as bad as to burn a hole straight through the piston.
Your engine will not make more power, it will not run cooler, and the fuel will not burn more slowly.
Now running race fuel on a stock 400ex, is like throwing money in the toilet ;).
Leaded fuels. These fuels are no longer widely available because of their emissions and potential damage to catalytic converters. Their benefits are that the soft lead cushioned the valve seats as the valves closed. This helped in engine longevity. Another benefit of the leaded fuels was their higher octane. I believe the engine also runs cooler.
Does anyone need claification on any of this? If so, just ask, happy to help.
Happy Trails!
Mike

[crashinmatt]

Originally posted by TRX300X
How does a Diesel engine run with no spark plug? It compresses the air fuel mixture.

i thought u said something about being a mechanic. deisel engines do not compress the air AND FUEL MIXTURE. justhe the air and then the deisel is injected into the cylinder at the right time and when the deisel hits the compressed air(which is at or above the burnin point of deisel), it ignites. not tryin to flame just clearing some things up.

and like RideSportrax said, lead does lubricate the valves, and slightly aids in cooling. most pump gas is not leaded cuz it destroys the internals of catalatic(sp?)converters, but is still in race fuels.

and whether race gas cools(like i was always told) doesnt matter as much, cuz u need the higher octanes on higher compression motors. but basically u should run the lowest pctane needed to save ur wallet more than anything else.

[TRX300X]

You're right I did say that. I got ahead of myself with the whole diesel thing. I'll get off my soap box now.

[jb400exxx]

i use 93 or 94 with 104 octane boost.

[RideRed04]

Exparament, try um all. Dont run the 89 octane, too many additives for the quads. 92-94 gave me more pull, so that is what I run.

[Chanman420q]

At my gas station we have 87 89 and 94... i run 89...

good goin stev-o u need to run 92+ octane. Honda put it in the manual for a ****ing reason. Don't listen to your friend down the street with the volvo.

good goin stev-o u need to run 92+ octane. Honda put it in the manual for a ****ing reason. Don't listen to your friend down the street with the volvo.

Leaded gas isn't used because a bunch of hippies protested to get rid of it. Then we put catalytic convertors on because getting rid of the lead (that an old muscle car need) wasn't enpugh for the damn treehuggers. Old cars backfire because they were made to run leaded gas. If an engine isn't made for leaded gas it isn't going to lube the valves or anything like that.

Rely on the manual for answers on gas and carbs, and not some of these retards telling you stuff that could seriously **** up the engine.

[Chanman420q]

ok i run a stock EX... and im not paying 1.64 a gallon. SCREW THAT

[Steve-o 400EX]

I really dont see why you wouldnt pay an extra 50 cents for a 5 gallon can of gas so ur ex can run better. Why is everyone so damn cheap.:rolleyes: Is it really that difficult to spend an extra couple cents that u could find in ur couch. Come on, give me a break. But it will cost u much more in a few years when ur EX is runnin like S*** and ur wonderin why callin it a piece of crap.:mad:

Read the manual, it says to run 92 OR BETTER octane in a STOCK 400EX. Which means u need to go even higher when u do motor work, that is why u see guys runnin 104 octane race fuels.