Commandos and Higher Octane Gas

Al-otment said:

hobot said:

Hehhehe>LOL pete.v you nailed ole Ludwig claims down good. His featherweight wonder would be a loaded down fuel tanker if what he stated was so over the distances he's proven to do in wonderful regions. Funnier yet is if Ludwig has tuned up engine to take advantage of extra octane/detonation resistance in low oxygen altitudes he'd experience same as comnoz did with his EFI dialed in just right to point that one event of questionable 87 octane slapped his engine apart on a tour trip last year. Peel will be immune to boozed/watered or poor fuel quality as can just select spark timing and throttle ease to get to better fuel station. If ya look up the octane boosters beyond their own advertising you'll see at best they can raise octane a point or two.

http://www.wallaceracing.com/octane-mix-calc.php

http://www.bazellracefuels.com/Calcs/OC1.htm

Click to expand...

Walter Mitty strikes again - the bullshit never stops on this forum. I suggest you actually try doing some miles on your bikes rather than speculating to the nth degree on what may or may not happen due to quality of fuel, preferred spark plug, oil viscosity, tyre sizes, correct shade of black etc etc etc etc. 10,000 miles last year between mot's on cheapest unleaded with ethanol purchased from garages in England, Wales, Scotland, France, Germany, Austria, Isle of Man. I'm off on a 3,000 mile trip through Scandinavia in June. Forum experts do no more than a few hundred miles a year. Sad but true.

Click to expand...

Wait.... you suggested frames trued within .0005"... and THEY'RE obsessing? :roll: I'm just sayin... How the hell ya been?

Opps, I apologize Ludwig for attributing the fuel mixing to you instead of pete-v. I am impressed enough with Ludwig's work to take his flak and enjoy the attention. The detonation subject often mentions carbon deposits as both becoming glowing embers to pre-ignite but also taking up space raising CR. A pump up water sprayer applied while blip ping up good pukes out lots of yuky grey carbon its turned to powerd for a bit more detonation protection. How low can a Combat go, at least with points at 28' its 50:1 gasil chainsaw mix. If ya ever put a dash of bean oil in tank it'll leave you and strangers grinning. Car/truck local racers use a lot of the grape scented hi octane till it makes ya sick of grapes.

About comp. ratio and ignition timing. A friend of mine has raced manxes at the top of our A grade in the early sixties. He used three setups with methanol fuel:
The standard compression short stroke manx he advanced two degrees over petrol timing to use methanol
The long stroke manx on 12 to 1 comp., he used standard petrol timing to run methanol.
The short stroke manx on 14 to 1 comp. he retarded the ignition two degrees.
,
There is a trend here if you think about it.

Mr Cotteral should be able to tell us EXACTLY what the 5 star 100 octane REFINED Pump Gas was IN 1970 .

And what this synthetic nazi aromatic tripe they flog of these days is made of . Recycled effluent ?

Oh my Matt its risky to allude to I.G.Farben influence with is daughters like Dupont and Monsanto. Ok here's a teaser tale to keep the hairs on back of neck up while filling up. Frank Foster on Brit Iron list, saying instruments are little defense when playing with fire >>>>

I recently had a piston failure on a B50 500 single that I define as pre-ignition.
I had it set a bit lean and was attempting to diagnose another issue.
I was running it up a high gear grade on full throttle when it began to slow appreciably. I could hear no odd noises and the engine temp gauges were showing cool running. In perhaps a minute the center of the piston crown dropped away.
Dis-assembly showed 'hammering abuse' all around the combustion chamber.
At no time did the EGT and CHT gauges show high temperature. I was using my normal running plug (ND W20).
The remaining bits of the piston crown, including the sharp edges of the valve cutaways showed no damage other than hammering by bits of metal. There was no sign of piston skirt seizure.
This bike is long term ownership with lotsa use. Previous incidents of detonation have been cured by enrichment of the cutaway and the needle jets with no visible damage to the piston.

Frank Forster

Can my engine be damaged by too high an octane rating? I can obtain 99, 104 octane here in Melbourne, FL; a Sunoco pump off by itself labeled Racing Gas. Does anyone know if this has lead? I do not need to add anything, correct? I presume there is no ethanol present.

I've only tried it once soon after finally getting the bike running, but could not tell much difference between it and the 93 ethanol-free I normally run. Using Pazon EI on a 1970 "S". Should I be able to notice any increase in power with high octane?

Last, What would be a good recommendation for daily use gas? My standard has been using 93 octane ethanol free from Charlies gas station near Satellite Beach for some time; no issues.

richardsonrl1100 said:

Can my engine be damaged by too high an octane rating? I can obtain 99, 104 octane here in Melbourne, FL; a Sunoco pump off by itself labeled Racing Gas. Does anyone know if this has lead? I do not need to add anything, correct? I presume there is no ethanol present.

I've only tried it once soon after finally getting the bike running, but could not tell much difference between it and the 93 ethanol-free I normally run. Using Pazon EI on a 1970 "S". Should I be able to notice any increase in power with high octane?

Last, What would be a good recommendation for daily use gas? My standard has been using 93 octane ethanol free from Charlies gas station near Satellite Beach for some time; no issues.

Click to expand...

The only damage from running race gas will be to your wallet.
You will not see an increase in power unless the compression ratio is increased to take advantage of the high octane. Jim

A higher than necessary octane gas will also carbon up the combustion chamber. A general rule of thumb is, use the lowest octane that doesn't ping or knock.
Bill

pantah_good said:

...........carbon up the combustion chamber...........
Bill

Click to expand...

Fact or opinion?

I was always told use highest test available .... the old boys said it burned cleaner .... not a fact just handed down wisdom at the shop .... I listened cause these guys had been around a while and I was younger .... cleanest engine I have had was 125 2stroke run on av gas only , clean as whistle inside ....
Craig

DogT said:

Fact or opinion?

Click to expand...

Sorry if that sounded like I'm some engine expert, I'm not. That information was passed down as gospel by noted Ducati engine expert and former owner of BCM Ducati, Laconia, NH., and I'm sure was meant for normal street usage. My experience over the years has seemed to bear that out though.

Higher octane fuel burns more slowly, so it stands to reason that if engine parameters (compression etc.) are not able to take advantage of slower burning that more unburnt hydrocarbons would result from it's use.

Does higher octane gas burn slower or does it have a higher ignition point ( temp ) or both ? High octane around around here is 91 and that's what I use , if I could get higher I would probably try it ....
Craig

Octane is a combustion inhibitor. Higher compression will cause the mix to pre ignite, or at least sooner than normal and therefore higher octanes, in the 100 plus range, should be used in conjunction with timing. If you are pinging and knocking, you might first check to see if your timing slipped to the advanced range. If your timing is set to around 31 BTDC, try 28 BTDC and see how it goes. Once that is corrected, boost octane as needed.

I think it is good to note that Electronic Ignition companies suggested advance setting is relative. That being said, I might still stay within the 31 to 28 degree range

Craig said:

Does higher octane gas burn slower or does it have a higher ignition point ( temp ) or both ? High octane around around here is 91 and that's what I use , if I could get higher I would probably try it ....
Craig

Click to expand...

A fuels octane rating and the burn rate are separately controlled by the chemistry of the fuel.

Higher octane means the fuel is better able to resist the spontaneous, explosive ignition of the remaining charge in the cylinder -before the flame front gets to them.

http://www.racegas.com/article/10

From what I have seen pump gas and race gas make the same carbon buildup if they are running at the same mixture. Some race fuels require smaller jets to run at the same mixture -and some fuels require larger jets.

Some race fuels contain lead which will leave a deposit in the chamber and on the plug. The color of this deposit was a good indicator of the air fuel ratio.

pantah_good said:

DogT said:

Fact or opinion?

Click to expand...

Sorry if that sounded like I'm some engine expert, I'm not. That information was passed down as gospel by noted Ducati engine expert and former owner of BCM Ducati, Laconia, NH., and I'm sure was meant for normal street usage. My experience over the years has seemed to bear that out though.

Click to expand...

Bruce also compared air cooled Ducati engines to Norton engines and once when talking rebuilds said he did not "get" the .0045" clearance thing with Nortons and could build them all day long at "one and a half thou" piston to wall clearance. What do ya think of that?

Biscuit said:

pantah_good said:

DogT said:

Fact or opinion?

Click to expand...

Sorry if that sounded like I'm some engine expert, I'm not. That information was passed down as gospel by noted Ducati engine expert and former owner of BCM Ducati, Laconia, NH., and I'm sure was meant for normal street usage. My experience over the years has seemed to bear that out though.

Click to expand...

Bruce also compared air cooled Ducati engines to Norton engines and once when talking rebuilds said he did not "get" the .0045" clearance thing with Nortons and could build them all day long at "one and a half thou" piston to wall clearance. What do ya think of that?

Click to expand...

I think [in fact I know] a Norton will not live through warm-up at .0015 piston clearance.

.002 might get you to the end of the driveway. Jim

Biscuit said:

What do ya think of that?

Click to expand...

I think that's got nothing to do with whether to run premium or not.

Been using nothing but 110LL avgas in mine since rebuild. The exhaust valves look clean so far, can't see the intake without taking off the tank and inlet cover. I have to say it runs good, no pinging and evaporates out of the carbs in about 2 hours and doesn't seem to leave any residue except that blue coloring they put in it, but it doesn't seem to bother anything that I can tell. Smells good too. Pazon SureFire at recommended timing.

Yes it does smell good DogT.... lead was mentioned earlier .... my bike seems to be working great on the 91 octane gas here ... the other day I noticed a lead substitute for sale at CT .... I think lead was used to boost octane and provide some lube back in the day .... would a substitute be useful added to gas for our old bikes ?
Craig