gas, 89..91??

[funkamongus]

what octane do you use?? I was told my viagra 020 is low compression and wants 87.. how about this dohc monster? 87? 92?

[arthurdent510]

The vision is actually a fairly high compression engine....  something along the lines of 10:1 if I remember correctly. (It's about the same compression as my Miata, and they recommend 91 for that)  because of that I run 91.  Some guys will say you can run lower /shrug

[akvision]

You want performance at 10:1; you need primium gas.
I remember 100 octane!!!!!!!!!!!!!! 8)

[Walt_M.]

These bikes run just fine on 87. Higher octane gas isn't better gas, it just has a higher anti-knock-index. Meaning it takes higher pressure to get it to explode. The Vision has a very efficient combustion chamber shape and it doesn't need the higher octane. You can run the higher octane is you want to waste money but you don't have to.

[treedragon]

Here in NZ we have a choice between 91 (regular) and 95 (premium) with 98 available on the "main routes". I find the bike runs fine on all of them however I get better mileage out of the higher octanes both in the bike and my old Nissan van so I always use the highest I can find which is usually 95.

As Walt_M said, a very efficient combustion chamber, (designed by Cosworth), as the performance difference it is hard to spot mileage is all for me, the roads here are too nice to be stopping to gas up.

[macroars]

In Norway it is mostly 95 and 98. I get better milage with 98 that 95, but keep on running 95 - it is cheaper, and I think that it turns out to be the most economical...

[inanecathode]

I've been running 85 on both the visions i've had and havent noticed any pinging or overheating. Use higher octane if you want, but know that it'll only make a difference if the engine wasnt running right with regular. Like if you take a lawnmower and put in 110 race fuel it wont run any faster, cooler, or better than it would on regular gas. It has alot to do with compression and ALOT more to do with combustion chamber shape. 10:1 is pretty high for a car engine, but those generally are wedge heads or pancake heads and arent designed to compress efficiently. Vision chambers are hemi heads and handle the higher compression a little better.
God help you if you have a bmw airhead though, they have Fischer Price My Furst Heads on them and ping if you look at them right. Even at 8.7:1 you have to run premium in them  :o

[QBS]

Been running the cheapest available gas for 25 years and 88k miles.  Never any fuel related issues.  Walt M is 100% on the money.

[Rick G]

95% of modern vehicles, need only 87 octane gas. People think that higher octane will "soup it up" .The Vision was a fore runner of a shallow combustion chamber (low included angle between the valves )  Its not susceptible to pinging at all. I've been running 87 for 10 years. (on QBS advice !!)
I put my engine together in 2005 and went back in in 2007 to replace the bottom end. Since I was using the bike to commute to work in low speed traffic, a great deal , it was fairly carboned up on top of the pistons. In spite of that  it showed no signs of preignition or pinging.  This thing was way ahead of its time.

[funkamongus]

good news!! Thanx, guys!!!

[supervision]

 better brands, with ability to keep intake valve deposit, away, is my preference.  I used to fill with cheep off brands, then, I developed a major case of intake valve deposit. now for about three years, I gotten rid of it with the name brand company's.  Mine has never pinnged so I use mostly low octane

[RadRacer]

I realize higher octane prevents pre-detonation, as well as most cars not needing it.  BUT, I've also been told higher octane burns alot cleaner as well; what's another $0.60 at fill-up to help prevent carbon deposits?

[inanecathode]

You were told wrong, the only difference in higher octane fuel is a higher octane additive, all it does is prevent predetonation, it doesnt have a cleaning effect  ;)

[RadRacer]

You were told wrong, the only difference in higher octane fuel is a higher octane additive, all it does is prevent predetonation, it doesnt have a cleaning effect  ;)

No actually cleaning effect, just a preventative.  Go check some fuel injector cleaners; alot of them will say "replaces high octane fuel" or something similar.

[inanecathode]

Right, because they have octane boosters along with cleaning agents (acetone, toulene etc). You have to add octane boosters to volitile cleaners like that because if you dont it'll actually lower the octane of the fuel you add it to.

[akvision]

thanks all

I sure learned alot about gas.  But even more about the Mighty "V".

[Kid Jedi]

I prefer gas w/o additives, But I can only get it on road trips when i run up to Idaho (3mpg boost). In my experience, its more about getting clean gas than what grade. but i still run premium. It burns more completely and I like mother nature.  And, well, I think my bike is worth it!  ;D

as of '06 shell, 76 and chevron had the cleanest gas by far, and the difference between them was slim. That was done by the EPA I believe, sorry I don't remember the exact source.

[funkamongus]

The gas I get up here in tahoe often times has mud, water, dirt, in the bottom of it because the tanks up here all leak.. I dont know why,, several stations up here have been forced to change out their tanks and have been forced to do it again just a couple years later.. Ive had bad gas in all my vehicles.. Wish I could ship some gas from Idaho.. Even off the hill at an arco, Ive had bad gas in my truck.... SHell 76 and chevron are the most expensive.. I wont, often, buy it. Ive bought it for trips, my truck has the engine service light on all the time,,, chevron can make my truck run right. No more O2 senor probs.. I STILL wont buy it, regularly.. too much money. 

[inanecathode]

Gasoline you buy from the end buyer (station) isn't pure, in fact i don't think you can get just straight gas. From the refinery the fuel has additives, so unless you've got a cracking tower in your back yard (I'm waiting on plans) it'll always have stuff in it. Colorado and some states use ethanol in the gas (10% here) and slightly different octane ratings (we have the lowest at 85) due to the altitude (less air etc).

Other states still use MTBE, which gets you better octane for less chemicals and it doesn't eat at fuel system parts. The only drawbacks i can think of is it doesn't hold water like ethanol does (engine can consume water fine, just large pockets and droplets that interrupt the fuel stream and corrode steel parts in spots), MTBE is ridiculously toxic and gets into the water table quickly and easily and i'm pretty sure it doesnt oxygenate like ethanol does.

All octane does, full stop, is prevent predetonation. In fact, if anything as far as burn is concerned, it actually slows down the burn slightly so depending on engine configuration it might actually harm mileage  :o
I like to run sea foam occasionally, helps keep the gremlins at bay :D

I can't remember what town it is, but theres one in california thats got nearly toxic levels of mtbe in the water table from continuously leaking in-ground tanks from the 60s-70s.

[The Prophet of Doom]

My advice would be to run a tank of regular to near empty, fill up with premium, and then decide for your particular machine.

It might just be chequebook syndrome, but I believe the more expensive premium grade works a whole lot better than regular.   On the Mobil web site they claim that as well as a higher octane, the premium petrol (gasoline) has a higher energy density.  They don't say by how much.