Speaking of octane. . . what grade do you use?

Cookie said:

I tend to tinker with a bike for quite a while and finally get it sorted to the point where I'm happpy with it and it is reliable.
During this time I just use premium grade from the local gas station. The ones I drive everyday, my yellow Goldwing and Red Chang get regular grade wherever they are low on fuel. My spare runner 76 goldwing LTD has been getting regular with fuel additive.
The Norton is closing in on being sorted to the point where she will sit until I want it. I'm thinking of the local airport for aviation fuel for her. I reckon she will use a few tanks a year in my use and the good stuff will prevent clogged carbs and such. Fuel is so bad now that the extra expense may be well worth it.

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Update on my detonation problem.
timing - kept retarding without checking with a strobe. Still getting a bit of pinging then strobed it...19BTDC at 4,000 rpms and still pinging
main jets - went from 230 (stock) to 240 to 260. Runs OK with 240s, but pings. 260s doesn't run well.
spark plugs - switched to BP8ES from std BP9ES. colder plugs don't run well. I'm getting a black glassy residue on the electrode toward the exhaust on both plug temps.
Starting to think there's an issue related to fuel and/or possibly the POR tank sealant used on my steel gas tank.

Right now not happy at all with the combat :cry:

Just for chuckles you might give her a tank of av gas and see what happens. I'm sure you checked to see how far the advance actually goes? I can't recall if you have an electronic ignition fitted.
Remember I'm the idiot who forgot the 49 mile drive.

Hi Cookie,

I have a Lucas RITA ignition. Believe I will try some race gas (108 octane leaded). If that clears up the problem it's easy to do and saves me quite a bit of time checking other things.

Don't worry about missing the 49 mile. Last time I went the group spent more time stopping than riding...hate that! :roll:

If that works you could just carry some octane booster on the bike if you need to fill up on the road. Most of the time you don't empty the bike all the way and you would usually be a bit of octane over pump.
The reason I mentioned ignition is a lot of time different systems have different curves. I fixed a friend's pinging wing by installing a Dyna. It worked so well I have one in stock for my daily rider for this winter.
Interesting about the stopping.

i'm in accord wihth illf8ed. back in the day, leaded "regular" had a motor octane rating of 96. leaded "high test", had a motor octane rating of 100. either had certainly enough octane to run a combat @ 10.1 : 1
i've seen a couple of you have mentioned using "lucas" additive. this is a good product, however don"t be fooled into thinking that it will boost octane. it absolutely will not!!! it will change the evaporation rate of whatever gas that you are using & help to stop "pinging", as the rate will help cool the mix, to a point.
proper leaded engines really like the residue left from the burn of tetra-ethyl lead. (how many of you have had to do valve jobs because of a burnt exhaust valve, or replace one? ) it leaves a bit of "ash " , if you will ,to cusion the blow of the exhuast slamming shut. along with those valve jobs many british bikes have ( and should have ) upgraded to an induction hardened valve seats, ( if i remember correctly , the materials used in the commando valve seats are HARD, & do not need to be upgraded )
if using an "octane" additive try to make the mix such that it reflects a true motor octane rating, as this was how the engines in almost all of the Norton range would have been rated. it is really , IMO , the way all should be , as we all see the result of the "new & improved " fuels , MORE PRICE,,,LESS PUSH !!

I stopped in at Raber's in San Jose yesterday. Complaining about the pinging in my combat, Richard mentioned others are having the same issue. At least three have changed to 89 octane rated unleaded and report the problem has cleared up. Sounds a bit fishy to me, but what the heck it's easy to try and cheaper than my notion to try some race gas. Will let you know after this weekend.

I'll be darned, that's the exact opposite of what I'd expect. I do run regualr in the wings with no pinging but I think they are only a bit more than 9 to 1.

I live on an airport and have access to 100 octane avgas - runs great in my '71 and has lots of stabilizers in it - it lasts along time before turning 'varnishy'.

Does the Avgas have ethonal in it???

Dave
69 S

As far as I know no. In some places Marine gas is also still good but that depends on local rules. You can imagine you don't want carb problems on airplanes.

I use a 110 octane racing gas and cut it 50% with premium noLead. Rather than a combustion sound, it gives a feeling and sound of a controlled detonation. Runs smooth as silk.

I tried 89 unleaded today. It didn't help. Re- checked the timing marks and set the timing at 26 degrees BTDC. Played with the low tension connection post on the Lucas RITA reluctor plate making sure there is no shorting. No difference between BP7ES and BP8ES spark plugs (NGK). I'll take it out again tomorrow to see if any of this helped. If not I'm off to the local oil distributor that has race gas.

I was considering racing gas in my regular driver wing today. I don't run it as much in the winter and i want it a bit stabilized. Franco said there was a local source but I must have gone to the wrong station. I gave her some Stabil and Techron instead.
I look forward to hearing how that works David.

Not Norton specific...but good reading.
http://www.motorcycleperf.com/techtips/gasoline.htm
Bill G

My stock 72' Roadster was running ok on 91 pump octane fuel - local fuel has no ethanol, yet anyway.

I have found about two litres of 110 octane race fuel added to a tank and topped with pump fuel really improves things, however. Acceleration is noticably sharper, especially noticable after the bike has wrmed up fully.

DogT said:

Does the Avgas have ethonal in it???

Dave
69 S

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100 LL av gas (LL means low lead, the only grade available today) has absolutely no alcohol in it. Despite its name however, It does have a good bit of lead.

I am young, 20, so I don't have the experience with th older gas. But the advice I got from the old man and a few of his old biker friends that work on Harleys regularly advised me to never retard the timing to compensate for fuel, it will make the engine run hotter, not something a Norton needs to do. His solution was to carry a bottle of octane boost in his saddle bag. besides, they sure do run better with as much advance as they will take.

The Norton shop manual I have( the original one) recommends no lower than 99 octane fuel

jnstrong said:

The Norton shop manual I have( the original one) recommends no lower than 99 octane fuel

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Just be aware that the manual octane recommendations will be for RON ratings (see my reply on page 1).