Is Premium gas necessary?

[pbm]

While looking through the owners manual of my newly acquired 1998 Virago I noticed that 'Regular' (86RON) gasoline is spec'd. I always thought that Premium was called for in motorcycles but now I'm wondering if it's necessary.
I know that running Premium in a car that calls for Regular is a waste and I'm wondering if the same is true here?

Opinions wanted....thanks.

 

[440Magnum]

It depends ENTIRELY on the engine- compression ratio, timing, head design, forced/natural induction, etc.

It has nothing to do with "just because its a motorcycle."

 

[HerrStig]

A bike that old with carbs usually has no means of adjusting timing based on a knock sensor so it would be wise to run some 87 and listen carefully. It may have accumulated enough carbon in the combustion chambers to raise the compression ratio a couple of points. It might be that 89 is more than enough even if you do hear knock on 87. Make sure no prior owner has applied the "golden screwdriver" to mixture or timing settings.

 

[Skittles]

Originally Posted By: pbm
While looking through the owners manual of my newly acquired 1998 Virago I noticed that 'Regular' (86RON) gasoline is spec'd. I always thought that Premium was called for in motorcycles but now I'm wondering if it's necessary.
I know that running Premium in a car that calls for Regular is a waste and I'm wondering if the same is true here?

Opinions wanted....thanks.


You are actually losing horse power and gas mileage running a higher octane than required. It will run the best on regular.

I had a 01 Yamaha FZ1 that was putting down 150hp to the wheels with the 1000cc engine. It put down the highest horse power on regular.

 

[LoneRanger]

Manual for my Duc says use no less than 95 RON (USA 91), which may mean they tuned it using that octane grade. I have been using 93 but probably ought to find some 91 to get best performance.

Elevation above sea level makes a difference too. The higher the elevation the less tendency for detonation an engine will have with a given octane. This is because higher altitude means less air density.

 

[kmrcstintn]

'Make sure no prior owner has applied the "golden screwdriver" to mixture or timing settings.'

I can attest to this statement...my '06 Shadow Aero 750 is notoriously warm blooded but was running really rough during cold warmups (45-60 degrees); during a carb cleaning last year my preferred shop told me that both my idle & main jets were 2 steps larger than stock & the fuel-air mixture adjustment was 1/4 turn below OEM setting (this confirmed our suspicions that the bike was previously setup for aftermarket pipes -- upjetted & fuel-air mix was cranked down to compensate when stock pipes were slapped back on prior to trading the bike); had the shop turn the fuel-air mixture up 1/2 turn which helps running in cooler temps and reduces lean running when engine is hot;

BTW...mine calls for 87 and that's what I use 98% of the time; I occasionally go up to 89 if bike sits a while & up to 91-93 for winter storage (gas drops octane rating as it sits...not sdure why)

 

[ARCOgraphite]

Can you avoid E10 problems at some pumps?

 

[WANG]

If this is the 1100 Virago, wikipedia says it has a compression ratio of 8.3:1. I'd say you'd be plenty safe following the manual and using regular old 87 (R+M/2).

When my Bandit (air/oil-cooled 4 cylinder) was stock it probably would have run on skunk urine if that was all that was available.

 

[Jarlaxle]

WOW...86RON?! That would be, what...80 or 82 pump octane?! Should be fine with 87 or even lower.

Then again...my 12.5:1 compression Burgman actually calls for 87 octane E10 fuel.

 

[ammolab]

Regular may do you just fine. My wife's 250 NINJA and my BMW K75C both spec and run fine on regular gas and making 100bhp/liter to boot.

Note that 86RON (Euro spec) is about 90.5 octane as measured on US pumps.



Formula for converting US to EURO octane
And reversing that forumula, wet get: RON = US*(22/21)

US (R+M)/2 EURO RON
87 91.1
88 92.2
89 93.2
90 94.3
91 95.3
92 96.4
93 97.4
94 98.5
95 99.5
96 100.6
97 101.6
98 102.7
99 103.7
100 104.8

 

[spasm3]

My gz is not high compression. I get better mpg on 87 vs 93.

 

[Pontual]

My ninja ZX9R Compression 11,5:1 ratio, likes some premium gas, maybe for the high ethanol content on all fuels here, it maay have some friction modifyer on it, that regular misses. But it likes regular 87 with TCW3 2 stroke added at 1:300, too, as much.

 

[southernjeeper]

use marine StaBil every time you fill up. If you are unsure about how clean the fuel system is and such... Use what you think is a nice amount for your liking of B12 chemtool fuel system cleaner. They sell for less than $5 at nearest wally world.

Works great in small engines and I bet it will work wonders for your bike!

 

[Olas]

So in US numbers, European pump gas is 91 for regular, 93 94 or 95 as premium and some stations near racetracks have 98 and higher upto 116 in Euro numbers but I don't know what that equates to in US numbers.

 

[SteveSRT8]

Originally Posted By: Olas
So in US numbers, European pump gas is 91 for regular, 93 94 or 95 as premium and some stations near racetracks have 98 and higher upto 116 in Euro numbers but I don't know what that equates to in US numbers.


We use an average of the Research and Motor octane numbers. That's one of the reasons our numbers are so different...

 

[alarmguy]

oops ... *L*

 

[alarmguy]

Using premium gas in an engine designed for regular can only hurt performance not give you better performance.
Not only that, using premium gas in an engine designed for regular can and most likely will GREATLY increase the chances of harmful deposits in your cylinders.

The reality is regular gas is more explosive/easier to ignite then premium gas. (most people think the other way around because the word premium)

In a high compression engine, premium gas is required because premium gas is harder to ignite. This prevents pre ignition in the cylinder which prevents the fuel mixture from exploding (igniting) before the spark plug fires.

SO the ONLY thing about "Premium" gas is the premium price, it is NOT a better fuel then regular gas, its only a fuel that is harder to ignite, due to lower production numbers and higher profits, premium gas is only premium in price, no better then regular, just different application.

Using premium gas in an engine that requires regular gas, simply may mean the gas does not get a chance to fully ignite and may/many times, leaves behind deposits in the cylinder and piston.

 

[Ramblejam]

 

[ammolab]

Premium gas resists "pre"ignition. I have never seen proof that it resists the spark provided by the ignition system to the point that it does not "fully ignite".

It surely is a waste of money but I don't see "deposits" remaining in all those engines built for regular that are pumped full of premium. It's pretty hard to make gas partially burn in a proper running internal combustion engine.

 

[Jarlaxle]

Originally Posted By: ammolab
Regular may do you just fine. My wife's 250 NINJA and my BMW K75C both spec and run fine on regular gas and making 100bhp/liter to boot.

Note that 86RON (Euro spec) is about 90.5 octane as measured on US pumps.



Formula for converting US to EURO octane
And reversing that forumula, wet get: RON = US*(22/21)

US (R+M)/2 EURO RON
87 91.1
88 92.2
89 93.2
90 94.3
91 95.3
92 96.4
93 97.4
94 98.5
95 99.5
96 100.6
97 101.6
98 102.7
99 103.7
100 104.8


No, that's backwards: the Japan/Euro RON numbers are HIGHER than the US (R+M/2) pump octane numbers. I recall 91RON is 87 here.