detonation

[quazi-moto]

I've always used 93 octane fuel in my goose and never experienced any pinging until recently under hard acceleration (like overtaking a vehicle on the highway) she'll ping a bit. If I drop down a gear it seems to help, but I don't want to keep running it like this over the long term.

[docc]

I'm just back from 1035 miles into the Virginia/West Virginia mountains. The Guzzi has never been so unhappy with fuel. Mostly only 87 octane was available, but I wonder if some 'corners' are being cut to give us the gas . . .

[Greg Field]

Get some Redline octane booster and add just enough to stop the pinging.

[Dan M]

There have been many threads about spark knock or pinging.

I thought I'd give some insight to the causes

 

When things are happening as planned, the spark plug starts the party. The flame spreads rapidly in all directions until the whole charge is burned. During combustion the pressure in the combustion chamber rises to several hundred psi.

The trouble starts when the last part of the mix explodes before the flame front gets there. As combustion pressures rise, the temperature of the mix increases. If the temp is too high the remaining mix will ignite before the flame front gets there. Under normal combustion the flame velocity is approximately 30 meters per second. When the mix ignites spontaneously the velocity can be more than 1000 meters per second. The shock waves of this violent explosion hammering against the inside of the combustion produces the clattering knock we hear.

Since temperature plays a roll, octane matters. The higher the octane the higher the flash point and the slower the flame front.

Anything that increases combustion chamber temperature will increase the likelyhood of knock: Higher compression; advanced timing; combustion chamber deposits; lean mixture; high engine load; high ambient temp.

Allowing this condition to continue unchecked can cause catastrophic damage to an engine.

 

Hope this helps.

[Janusz]

There is hardly a combustion problem which cannot be solved with a little adjustment of your powercommander (you do have a Powercommander, dont you).

[roberto tenni]

I recently rode up the Stelvio Pass, two-up with full luggage, after filling-up with 95 octane - pinking like crazy.

After filling-up with 98 octane, no pinking on any subsequent passes - it really liked the good stuff.

[gstallons]

Pinking? Just joking..

I ALWAYS run Premium gasoline in any bike.I feel better about it. All my buddys run as cheap as fuel as possible.

[Slavomir Musilek (R.I.P.)]

unless you have engine set up directly to Gasoline with higher octan number (like BMW has sensors for 98 premium octane) it is just waisting money I have never experienced problems with the most usual and cheap Gasoline 95. (however I dont buy petrol from stations like Tesco, Globus and ect. I once felt very strange when filled 5 litres canyster and had to pay for 6 litres <_>

 

 

hey I forgot you have 87 octans in the states

[Janusz]

There is a different method of defining pump octane # in North America then in Europe. You should remember that.

 

Canadian (and US) octane 87 is an equivalent of European 91/92. V11 Guzzi owner's manual specifies unleaded 95 octane RM ; as I said this is a Research Method octane # which is same as ours 91 R+M octane at most. The manual also specifies Benzina Super 97 RM which, as I seem to remember from my Italian travels, is a leaded gasoline.

 

Anyways, my experience was that any engine pinging was caused by too lean fueling, especially extremely lean after opening an airbox and/or freer muffler. In my case adding fuel at pinging throttle/RPM points of Power Commander completely cured any pinging I ever had. Using too high octane gas is a bandaid solution bad for engine and bad for your pocket.

[richard100t]

First thing to check when it starts pinging is the throttle bodies to see that they are still perfectly balanced. I have heard that you should try not to use gas with ethanol in it if you can avoid it. That may have been part of your problem too. If your tb's are balanced then the tps is the next thing to check, then the valves. If it still pings after that I'm out of advice

[dlaing]

Yeah, what Richard said.

In that order, each time checking to see if problem goes away:

Balance your TBs, Check your TPS, Adjust your valves.

 

But if it is tune-up time, then do it in reverse:

Adjust Valve, Adjust TPS, adjust idle, balance TBs.

 

Dan M. did an excellent post on the cause of pinking.

Keep in mind two of Dan's points, too lean, and too much carbon buildup. While enrichening the mixture reduces pinging short term, it is can increase carbon buildup, and the long term result can be a greater tendency to ping. A PCIII should be used to eliminate both lean and rich spots on the map.

 

Other solutions such as Tuneboy, Directlink, and MY15M offer ignition adjustability, which can do more for the map and optimizing burn, than simply modifying the richness.

 

Still others reshape their combustion chambers for better squish.

[Janusz]

Keep in mind two of Dan's points, too lean, and too much carbon buildup. While enrichening the mixture reduces pinging short term, it is can increase carbon buildup, and the long term result can be a greater tendency to ping.

 

I respectfully disagree.

 

If the pinging is caused by too lean mixture (which is the case with a stock setting to begin with and then, after some modifications to intake/exhaust it becomes really excessive) then richening is NOT the short term solution BUT the only proper one and no carbon build-up is expected.

 

Once again: first make sure the mixture is close to proper one and then worry about valves, TPS, idle, balance etc.

 

Unless Im missing something. If that is the case please tell me what.

[rocker59]

My Nero Corsa will ping occasionally under load, usually at rpms below 4500.

 

I've run RON+MON/2 octane ratings as low as 87 and as high as 93.

 

The bike has pinged on all octanes under various conditions. There has been no rhyme or reason to it...

 

Personally, I think the pinging has something to do with the variability of fuel at different stations in different regions than it does with anything else...

[Steve G.]

There is a different method of defining pump octane # in North America then in Europe. You should remember that.

 

Canadian (and US) octane 87 is an equivalent of European 91/92. V11 Guzzi owner's manual specifies unleaded 95 octane RM ; as I said this is a Research Method octane # which is same as ours 91 R+M octane at most. The manual also specifies Benzina Super 97 RM which, as I seem to remember from my Italian travels, is a leaded gasoline.

 

Anyways, my experience was that any engine pinging was caused by too lean fueling, especially extremely lean after opening an airbox and/or freer muffler. In my case adding fuel at pinging throttle/RPM points of Power Commander completely cured any pinging I ever had. Using too high octane gas is a bandaid solution bad for engine and bad for your pocket.

Completely agree. High octane fuel is basically laden with flame inhibitor to stop "pre-igniting". This high octane fuel will substantially reduce your fuel economy as well as cost more per litre/gallon. In Western Canada we have RON 94 octane, Euro 102, in the major cities and suburbs "Chevron" and this is the diet I feed my V11. Even here, my bike pings when I roll it on below 3500rpm. This pisses me off. But I've heard good, and bad stories with the PC units, and this to me is also an expensive bandaid.

What I'd like to "try", is to find out if, and how, to reduce the spark advance just a bit so the bike will be able to run on 89, which can be found anywhere here in the smaller towns. Pinging is bad for the engine, and I can deal with a bit less fuel economy with the reduced advance, which may well be compensated for with the lower octane fuels, which offer higher fuel range anyways, since they have less flame inhibitor and, as a result a higher BTU [explosion].

Steve

[richard100t]

I respectfully disagree.

 

If the pinging is caused by too lean mixture (which is the case with a stock setting to begin with and then, after some modifications to intake/exhaust it becomes really excessive) then richening is NOT the short term solution BUT the only proper one and no carbon build-up is expected.

 

Once again: first make sure the mixture is close to proper one and then worry about valves, TPS, idle, balance etc.

 

Unless Im missing something. If that is the case please tell me what.

I agree that you need to richen it up a good bit if you modify the intake or exhaust. If you open either end up & dont give it more fuel it will ping.