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What grade of gas to use


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what grade of gas do you folks recommend for my 03 v11 sport, with the MG racing titanium exhaust system with ECU. regular ,mid grade or premium? On my kawasaki nomad, even though kawasaki recommends premium, most big vulcan owners find that running premium contributes to carbon buildup on the piston crowns and subsequend preignition/pinging. the cure is running some seafoam in a tank or 2 of gas ,and running the bike hard a few times to the rev limiter to blow out carbon, then running 87 octane from then on. thats what ive done with my nomad with good results. whats the best for my Guzzi?

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I think most of us have been running Premium, but after a few thousand miles, yes the carbon builds up, and yes some of us have gotten pinging. But we have never been sure it is related to Carbon build up.

I did not think a difference of a few octane points would lead to carbon buildup on an engine that the manufacturer recommends 95 NO-RM minimum.

I am not sure what 95 NO-RM means, but I'll bet the 91 R+M/2 that they serve up as Premium in California is a lower octane.

A PCIII should keep your engine from running too rich.

The general rule is to use the lowest octane rating that never causes pinging.

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Just out of interest, I tried the Shell V Power 100 octane on the German autobahn a few months back and the motor felt good for it.

 

Never seen the 100 octane stuff sold elsewhere aside from Germany.

 

Normally use 98 octane with no pinking issues.

 

Guy :helmet:

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Guest Nogbad
what grade of gas do you folks  recommend for my 03 v11 sport,

58329[/snapback]

 

The highest octane you can get. The V11 combustion chamber design is unsophisticated, and the compression is high. High octane gas gives the best chance of avoiding detonation whilst maintaining the proper air / fuel ratio.

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I think most of us have been running Premium, but after a few thousand miles, yes the carbon builds up, and yes some of us have gotten pinging. But we have never been sure it is related to Carbon build up.

I did not think a difference of a few octane points would lead to carbon buildup on an engine that the manufacturer recommends 95 NO-RM minimum.

I am not sure what 95 NO-RM means, but I'll bet the 91 R+M/2 that they serve up as Premium in California is a lower octane.

A PCIII should keep your engine from running too rich.

The general rule is to use the lowest octane rating that never causes pinging.

58332[/snapback]

 

To go into the "FWIW" file:

 

the "95 NO-RM" probably means 95 normal octane, by the research method.

 

The "91 (R+M)/2" you see on the side of a CA gas pump (most U.S. pumps, for that matter), is actually a *higher* rating that you'd otherwise think, since it is an average of the Research [the "R" in the (R+M)/2] and Manual(? - whatever, the "M" in the formula) methods. Since the Manual method is the only real means of getting a meaningful octane rating, & it's always a lower # than the Research (a "best case; this is what it should be in theory") method says, your 91 octane U.S. gas [(R+M)/2] is at *least* a 93 RON ["Research Octane Number"], & probably higher than that, if you're outside CA buying real gasoline, not the oxygenated cr@p they sell inside our state borders.

 

The problem with the Research method is that it assigns an "octane value" to each component, & then you multiply by percentages & blahblahblah to come up with a number that's essentially an estimate of what the octane rating *could* be, if the numbers you started off with weren't so full of sh!t... The problem with the Manual rating is that you actually have to *run* some gasoline thru a special test engine to come up with the number, and it's always so dang low compared to the Research method that people hate to use it. Think how embarrassing it would be to try selling your gas at 86 MON when somebody else is selling their 94 RON gasoline? It doesn't matter to most of the public that your 86 MON actually has about a 95 RON equivalency... Hence the decision to avg. the two ratings to come up w/ some sort of standard that combines the real world with blue sky numbers! ;)

 

Ride on!

 

:mg:

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Great answer Skeeve!

Another thing that can cause carbon build up is going for too short of runs.

The bike runs much richer for the first few miles, especially if the air is cold.

And to make matters worse the carbon won't burn off until the engine is at a decent operating temperature.

So if your commute to work is under half an hour, you may need to find a longer route, hopefully with some twisties. :race:

When you arrive late, just tell your boss that you are just trying to prevent carbon build-up.

They should understand, otherwise you may need another job. :P

And to risk sounding like a broken record, getting a PCIII and the bike dynotuned can help maintain the proper Air:Fuel ratio.

If you ever look at a PCIII map for a stock Guzzi, you will notice that the stock ECU puts out both too much fuel in some places and too little in others. Before I knew that, I assumed it would just run too lean to pass emission testing.

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My V11 will only be happy with 94 octane, and that is only available at Chevron here in Canada, and only in big cities. Spent a day and 300kms in Washington state Sunday, and 92 does not work for the crude combustion chamber of a Guzzi.

Ciao, Steve G.

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My V11 will only be happy with 94 octane, and that is only available at Chevron here in Canada, and only in big cities. Spent a day and 300kms in Washington state Sunday, and 92 does not work for the crude combustion chamber of a Guzzi.

Ciao, Steve G.

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Wow, using high octane fuel can cause carbon buildup which then results in pinking. I'm really struggling with that concept.

When my bike arrived from the U.S. it had a tankful of a foul smelling liquid that would have been sold as petrol. I don't know what it is made of but it is definitely different to what we buy. The first time I removed my tank I did not know the tap had not closed off completely and subsequently when I removed the fuel line I ended up flicking some of this fuel into my eyes. Nothing happened at all, I couldn't believe it as when I accidentally did this with our petrol it was a very, painful experience. Kids don't try this at home...

I have always run my bike on our 91 octane without a hint of any pre-ignition or pinking even before I fitted the PC. Now for a silly question, has anyone checked the timing of any stock bike prone to pinking? If high octane fuel is being used what else apart from timing can cause this pinking?

Rob

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Great answer Skeeve!

...

If you ever look at a PCIII map for a stock Guzzi, you will notice that the stock ECU puts out both too much fuel in some places and too little in others. Before I knew that, I assumed it would just run too lean to pass emission testing.

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Aw, shucks! [rubs toe in dirt] Tweren't nuthin... :blush:

 

WRT "just run too lean..." that's *exactly* what it does! If you look at the stock map, it's *absurdly* lean at idle - 3000rpm; this is the range that most EPA/CARB [sorry, can't speak for the rest of the world] testing occurs: they test at idle [because most vehicles spend more time idling at stoplights in urban areas where air pollution is worst] & at just above idle [cruising rpm; where the other major time component is spent on most vehicles.] The rest of the map Guzzi runs at optimum [just a little richer than stoich'] or too rich [

 

Whaddaya gonna do? Budget for a PC3 & be done with it...

 

Ride on!

:bike:

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Wow, using high octane fuel can cause carbon buildup which then results in pinking. I'm really struggling with that concept.

...

Now for a silly question, has anyone checked the timing of any stock bike prone to pinking?

Rob

58393[/snapback]

 

The reason the high-octane fuel leads to carbon buildup is because when the engine isn't fully warmed up, the carbon accretes onto the colder (relatively) metal parts; if you don't run the engine long enough to get it fully warmed up, the carbon just starts building up.

 

It's easy to clean out by running the engine till it's good & warmed up, then squirting a water aerosol down the intakes while the engine is at about 1/2 throttle. Steam cleans the chamber & points south! HUGE clouds of black smoke, followed by white. But you gotta be careful; do it wrong [too much liquid water, not aerosol] & you get hydraulic lockup & blow your motor.

 

As far as the timing of a stock bike goes: this is the drawback of the all digital engine management system! They're all 31 degrees BTDC at full advance now, Guzzi's decision. [This is why there's people who keep pressing Todd Eagen to get Dynojet to offer the timing module for the PCIIIusb for Guzzis, so we can adjust it to suit our needs! :) ]

 

:mg:

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  • 15 years later...

Daniel, if you have a Baggy 660, plain old regular unleaded is fine. It's an MZ though.. not a MG..

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I have a V11 with Mistral slip-ons. I live in the Los Angeles area and run Mobil Premium unleaded crappy Cali ethonal gas from my local station, unless I am passing through the Griffith Park area and then I’ll fill up with the 100 octane pump race gas at the Chevron station on the corner of Riverside and Fletcher. It may be 100, but it still has ethonal. The bike seems to enjoy that gas, but it’s pricey and my bike runs pretty good on my local gas. I also put Star-Tron in the tank, it’s readily available, and I love my chainsaw, too. I am assuming that the bike has the factory map and I have never messed with the map and tuning other than the slip-ons. I have never had any pinging, and the bike will pull no problem below 3k rpm.  I don’t know about possible carbon build-up from premium gas, but the bike runs smooth and pulls like a fast train. I ride a 70 mile round trip commute most days. I need to gas up after two days of commuting 😳. Mileage is a little better than my truck, but it ain’t no moped.

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I do the same, I run Shell 93 and dump in about a gallon or so of 108 race fuel. I’ve not heard of carbon buildup using premium. 
 

I just emptied the can of the expensive stuff in my Centauro and let her take a couple chugs... she perked right up.

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