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Petroil Mixes
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Neil_EngUK
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December 30, 2013 - 9:00 pm
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I have read differing recommendations and experiences regarding oil & petrol ratio mixes, and this forum contains some good advice and detailed experiences.

 

Consequently, I have compiled the following spreadsheet detailing recommendations from some of the BSA and other respectable published sources.

Mix Ratio Liters Petrol Milliliters Oil % Notes Source of 'Recommendation'
16:1 1 62.5   Normal BSA Service Sheet 502 - The Petroil Lubrication System (1965 D1, D3, D5, D7)
        Running In BSA Bantam (Wright) p.88
16.5:1 1 60 6    
20:1 1 50 5 Running In The BSA Bantam Bible (Henshaw) p.109
        Normal BSA Bantam (Wright) D1 & D3 p.49, D5 & D7 p.76. D10 p.121
        Racing BSA Bantam Racing Manual, Ch5. Technical Ramblings (Tibbitts) 1985 "<20:1"
        Running In BSA Bantam Workshop Manual (D14/4) p.A3
        Using non 2 stroke oil BSA Service Sheet 502 - The Petroil Lubrication System (1965 D1, D3, D5, D7)
24:1 1     Normal BSA Instruction Manual (1967 D14/4) -  p. 22
        Normal BSA Bantam (Wright) p.88 "Later models". D14/4 & B175 p.121
        Normal BSA Bantam Workshop Manual (D14/4) p. A3
25:1 1 40 4    
32:1 1 31.25   Normal Haynes BSA Bantam Workshop Manual  (Clew) p.7
        Normal BSA Bantam (Wright) p.88 "Modern 2 Stroke Oil Allows"
        Using non 2 stroke oil BSA Instruction Manual (1967 D14/4) -  p.22
        Using non 2 stroke oil BSA Bantam Workshop Manual (D14/4) p.A3

If I have got any of this wrong, please correct me and/or amend the spread sheet accordingly.

You 'pays your money and takes your chance' laugh

Kind regards

Neil 

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Neil_EngUK
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January 5, 2016 - 8:26 pm
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Following recent events, i will now be using 16:1 mix - permantly. - (300 ml of oil per 5 lites of petrol minimum)

I have never skimped on the oil, always mixed it properly and run the bike in on 16:1. After a full run in, i upped the mix to 20:1 5% mix. I use a quality oil brand and have tested that it doesnt settle or separate when stored.

However, i recently lost a piston, rings and small end bearing. Fortunalty the bore, mains and big end were fine. Very lucky.

I know some people have never had issues using lean mixtures, but ill be playing safe in future.

16:1 forever.

Kind regards

neil

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bart
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January 5, 2016 - 8:37 pm
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oh the oil thread.... 16.1 ?  good luck with that

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cocorico
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January 5, 2016 - 8:54 pm
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Wish I had £1 for every 'Petroil' post I've seen while sorting through Tech Questions. stick-poke_gif

I use 4% by the way (25/1) and do in all my 2 strokes except the chainsaw, which is 2.5%(40/1) and still running well after 7 years at full throttle.

Any old 2T oil too.

1956 D3 running, lights to sort. 7 other bikes in the Barn. 1950 D1 engine being rebuilt (slowly).

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Mags 1
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January 5, 2016 - 9:04 pm
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Stihl two strokes usually run on 50 to one, a bit too little I'd say, for a bantam, but still air cooled two stroke engines, highly stressed too.

I think the general consensus the last five times this subject was aired was "do what pleases you" with your own bike/s ?

Four now on the road and at least several in bits.

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Lone Wolf
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January 6, 2016 - 12:52 am
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Wotcha.

As far as I'm concerned it ain't an exact science - I tend to slightly overestimate a 30:1 mixture . . . . so mine is running anywhere from 25:1 to 30:1  -  it ain't gone bang yetfingers-crossed

^..^

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bart
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January 6, 2016 - 8:18 am
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Lone Wolf said
Wotcha.

As far as I'm concerned it ain't an exact science - I tend to slightly overestimate a 30:1 mixture . . . . so mine is running anywhere from 25:1 to 30:1  -  it ain't gone bang yetfingers-crossed

i agree, but 16.1 is way off i think..

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cocorico
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January 6, 2016 - 9:57 am
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My view is - if it smokes a lot - reduce the oil. If it doesn't smoke - increase the oil.

I once had an ETZ250 with oil injection, was doing about 70 up the M6 once, no smoke at all, going well when it seized! The 2T oil in the tank had jellified for some reason and the oil pump wouldn't pull it through fast enough. After a cool down and change of underwear on the hard shoulder, I kicked it over, started and limped home, then to the pub.cant-look

1956 D3 running, lights to sort. 7 other bikes in the Barn. 1950 D1 engine being rebuilt (slowly).

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BonesCDI
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January 6, 2016 - 10:46 am
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cocorico said
Wish I had £1 for every 'Petroil' post I've seen while sorting through Tech Questions. stick-poke_gif

I use 4% by the way (25/1) and do in all my 2 strokes except the chainsaw, which is 2.5%(40/1) and still running well after 7 years at full throttle.

Any old 2T oil too.

I do exactly the same...............25:1 synthetic on every 2 stroke I own including the chainsaw, brush cutter etc.

Have never had an oil related issue.

I also agree that any old 2T oil will do as well for a Bantam / Villiers engines.

How many "budget" oil producers and refiners are there? But how many generic brand 2 stroke oils are there? You will probably find that the bulk of 2 stroke oil is blended by only a few of the "big" oil producers...........sold off in bulk to be repackaged.........and then put into a flashy bottle to be able to charge more.

I don't think the ratio is such an issue............but having oil in your petrol is!

Bonesthumbs-up

Running and project bikes from 1912 -2005..........She hasn't said stop yet.........

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Derek's D5
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January 6, 2016 - 12:40 pm
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Blimey, that's quite a range from the 'official' sources. I go by the imperial instructions on the petrol cap, which is 4 measures per gallon. I did measure the capacity of the petrol cap once, it was about 50-60 ml I think. So I bung 200 ml of oil into 5 litres of petrol. That's 25:1. A gallon is less than 5 litres, and the petrol cap holds a little more than 50 ml, so I'm putting in a little less oil than the cap is telling me to do, but it's easier to work with round metric figures and I don't thrash the engine. All seems OK. There's enough smoke to tell it's a two stroke, but not enough to make the street look like downtown Beijing.

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nickjaxe
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January 6, 2016 - 9:19 pm
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Dont forget...to much oil may not do your engine any favors...it has the effect of weakening the fuel mix that gets burned.

The fresh in coming charge of petrol is important in cooling the piston to avoid seizures...

Weak as in not as much petrol because of excess oil.

One thing I have learned through years of operating a 2 stroke in my microlight aircraft is not the thrash the motor till its good and warm...or the piston heats up much faster than the metal cylinder and can cause a size...it called a cold seize.

That runs at 50/1 and spends its life running at between 5000 to 5500 rpm depending on load.

It looks much like my B175 inside.

Nick.

My Bantam video              https://www.you.....jpOFmzRZRI

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Neil_EngUK
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January 10, 2016 - 1:55 am
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Thank you for all the interesting comments, on this impossible subject. But ... people arent detailing the mileage they are doing, on low oil mixture. Sure it will go like a dream smoke free for a while, but id be interested in honest mileages please to give any claims some degree of authentication.

Im not asking for advice or giving any recomendations, but just stating what has happened to me and that 16:1 is working good for me.

At 16:1 (300 ml per 5 litres) the bike is now fully run in. It smokes a little but not excessively. If you dont want smoke, dont run a bantam. im not pretending they would meet current new bike emissions testing, but being historic, they dont have to. My banty at 16:1 has not fowled a plug yet and starts first time. It cruises very resepectibly at 50 - 55 mph, but will do more if required. Done several hundred miles since rebuild and run in a few weeks ago, with no ill effects.

More oil in petrol means more oil to bearings and cylinder. 25:1 & 33:1 meant blown up bike and worn out bearing. 16:1 so far means working running bike. Not just for a ride arround the block, but serious winter cruising.

I wouldnt like to compare chainsaws or anything else, to a bantam. Consider the differences in engine tolerances, metal alloys and compounds, metal expansion rates, cooling properties, rev exposure, oil mixing tecnology etc etc etc. Cant compare apples to bananas.

Regarding the perported heating and cooling issues, i trust this has a lot to do with the tightness and quality of the bore, as to whether your going to have issues. In incomming oil is the same temperature as the incomming petrol its mixed with, and will cool equally well. Extra petrol will explode and create extra heat, whereas the extra oil will lubricate more before it is burnt or vaporised (mostly to water vapour). Plus, if you dont ride the bike often or much, its never going to function properly. Maybe some are  scared of doing some damage, because you dont put enough oil in? 😉

16:1 is a pokier mix today, than 16:1 when BSA wrote the manual, as unleaded premium has a far higher octane than the original pool petrol available after the war.

regards

Neil

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nickjaxe
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January 10, 2016 - 9:34 am
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Just to add...a rich petrol mixture burns cooler than a weak petrol mixture.

I dont know which Bantam you ride but the crank roller bearings in mine are lubed by gearbox oil...bar my small end bearing.

But the main thing is your bike runs fine...and with the mileage you do its proved its self.

My Bantam video              https://www.you.....jpOFmzRZRI

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jess steele
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January 10, 2016 - 12:10 pm
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nickjaxe said

I dont know which Bantam you ride but the crank roller bearings in mine are lubed by gearbox oil...bar my small end bearing.

But the main thing is your bike runs fine.

Hi nick,was you having a senior moment?,the big end is only lubricated by petroil like the little end,it's only the mains that are oiled by gearbox oil on the engine side.......

Oil always a slippery subject..................

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BonesCDI
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January 10, 2016 - 12:12 pm
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Hi Neil,

I run 25:1

My Bantams do 200km runs, sometimes in plus 30 degree heat. My 150 D3 has 3000 miles on it since rebuild, and the D7 hasn't had a rebuild in the past 6 years. I also have 2 strokes from Husqvarna, Cagiva, Yamaha, CZ, Villiers and Suzuki. Apart from the Cagiva and Suzuki, all the others are premix. Never had an oil related issue.

I would disagree with a couple of your theories, firstly combustion. A rich mixture actually burns colder due to the highly enriched atmosphere in the cylinder unable to attain full combustion due to the oxygen having been displaced. Think of a 2 stroke leaning out and generating more heat and seizing.

Oil also can't vaporise and turn to water.................it's a hydrocarbon.

Of all the 2 stroke engines mentioned in this thread, chainsaws and all, the Bantam engine would be the least stressed of the lot. So those other more highly stressed engines actually run lower amounts of oil with closer tolerances with no detriment.

As for being "scared" of running higher oil mixes, I don't because it's not necessary. It's a personal choice I have made based on science...................I work for a major oil company and have ready access to good info.

Modern 2 stroke oils have been blended to increase lubrication properties, reduce smoke emissions and reduce carbon build ups in ports and exhausts, under all conditions. If you read most motorcycle 2 stroke oil bottles, they will say "for motorcycles and other air cooled 2 strokes, excluding outboards" or words to that effect. Oil companies won't blend too many unique types of 2 stroke oil. They are all reasonably generic.

So my choice is to do as the oil manufacturer recommends. It has proven itself by not having being stopped for a fouled plug and no damage to my bikes.

And your choice is yours.cheers

Bones

Running and project bikes from 1912 -2005..........She hasn't said stop yet.........

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nickjaxe
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January 10, 2016 - 12:28 pm
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I think I must have Jess of course your right...the big end gets its lube from petrolmix.

My Bantam video              https://www.you.....jpOFmzRZRI

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jess steele
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January 10, 2016 - 12:33 pm
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nickjaxe said
I think I must have Jess of course your right...the big end gets its lube from petrolmix.

we all have um nick,don't we?.erm were was i nowunsure

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Mags 1
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January 10, 2016 - 1:15 pm
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Chain saws have much smaller engines and so smaller tolerances, not larger!

Apples and bananas are both fruit!

But seriously now, I've done over three thousand miles on my D7 in about 3 or 4 years since it's full rebuild.

Admitted, I have had a few annoying problems, but no full lock up seizures, piston wear yes, admittedly.

I put a 100 mill bottle of good quality modern 2 stroke oil into a gallon of petrol, about 30/40 to one. 100's into 4500 is 45, but I fill the bottle right up to the very top from a gallon can of oil.

I bought that gallon months ago, there's only about a pint or so in it now, as I go out about once a week and like to do a minimum 100 miles when I can, most I've done is 122 miles one day last Summer, so far.

These bikes thrive on being used.

Four now on the road and at least several in bits.

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Mick W
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January 10, 2016 - 1:19 pm
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These comments are on the Fuchs Silkolene web site. Who may have some knowledge on oil

** Please log in to view **

Q. Having spent hours discovering the vast range of 2 stroke oils available, I am now totally confused! Advice on ratios varies from 20 to 1 through to 50 to 1. What 2 stroke oil would you advise for a BSA Bantam 175cc D14 of 1968 vintage. At 42 years of age I would like to use a product to prolong the life of this engine. 

A. Keith, Super-2 is a good choice. Don't worry about the word 'Injector'; it is also OK for tank mix. Has the engine been rebuilt recently? If so, Start at 20 : 1 (5%, 50ccs per litre) and if you find this causes plug oiling cut back to 25 : 1 (4%) 

Regards
Oil Clinic Team

 

Q.  Hi there, building a BSA Bantam pre 65 trials bike,what 2 stroke oil do you recommend and what ratio should I run? 

A. Brian, Use Super-2, or Comp-2 if you prefer a low smoke oil. Start at 30 : 1 (33ccs per litre). After running-in you may need to cut back to 40 or even 50 : 1, particularly in trials with a lot of slow sections. 

Regards
Oil Clinic Team

 

I don't know who Keith or Brian are maybe forum members who have seen this question a number of times. Take from the experts what you will

 

Mick

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Neil_EngUK
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January 10, 2016 - 2:50 pm
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