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1955 BSA Bantam oil/ gas ratio #636972
01/25/16 8:38 am
01/25/16 8:38 am
Joined: Sep 2008
Posts: 720
Edgewater, Md
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Blown Income Online content OP

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Edgewater, Md
Hi Everyone,

I recently picked up a 1955 Bantam Plunger for my oldest daughter to learn to ride on.

Question on the oil/ gas ratio, Do I use 2 stroke oil or regular 40wt? The manual I have doesnt really tell. The fuel filler cap has the tube attahced for the oil mix but I am assuming that is for regular oil?

Any help is appriciated.

Thanks

Chris


1955 BSA Bantam D1 Plunger
1956 BSA A10RR Street and LSR Bike
1961 BSA C15S
1966 BSA spitfire
1969 Triumph T100C
1970 Triumph TR6R
1972 BSA Lightning LSR Bike
1974 Triumph T150V
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Re: 1955 BSA Bantam oil/ gas ratio [Re: Blown Income] #636973
01/25/16 9:06 am
01/25/16 9:06 am
Joined: Sep 2005
Posts: 5,963
NL
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Ger B Offline
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NL
The two stroke scooter teenagers around here mention 1:50 two stroke oil.


Ger B

Re: 1955 BSA Bantam oil/ gas ratio [Re: Ger B] #636980
01/25/16 10:41 am
01/25/16 10:41 am
Joined: May 2004
Posts: 3,569
Sydney Australia
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BSA_WM20 Online content
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Sydney Australia
The specified ratio is 8:1 using engine oil,,, because that is all that was available at the time.
Modern blue smoke oils are chalk & cheese compared to motor oil and yes, probably 50:1 would work OK.

Two little tests
You should get a whiff of blue smoke when opening up the throttle fully
And the inside of the muffler should always feel a bit oily.

I ran a Jawa on a very lean mix around 1/4 of the recommended oil level with absolutely no problems lubrication wise.

However if I went any leaner I could not get a lean burn so I always assume that the thinner mix was going through a hole designed for thicker mix and thus it was running rich. A plug which sooted up faster than oiling up sort of confirmed my opinion.

And congratualtion for opening up the wondrful world of BSA to another young person.


Bike Beesa
Trevor
Re: 1955 BSA Bantam oil/ gas ratio [Re: Blown Income] #636990
01/25/16 11:17 am
01/25/16 11:17 am
Joined: Feb 2008
Posts: 4,129
New Jersey USA
Tridentman Online content

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New Jersey USA
8:1??????????????????--that sounds much too much oil--even in the old days.

Re: 1955 BSA Bantam oil/ gas ratio [Re: Blown Income] #636991
01/25/16 11:19 am
01/25/16 11:19 am
Joined: Aug 2012
Posts: 305
Hampshire, England
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Hampshire, England
My BSA Bantam B175 (1971) used to run perfectly for thousands of miles on 32:1 mix of 2-stroke oil.

My suggestion for an earlier bikes is to use 25:1 with a basic modern 2-stroke oil (no real need for expensive synthetics). My B175 has a needle roller little end which required a little less oiling that a plain bush, hence my recommendation.

HTH


BSA: '71 B175; '68 B25; '71 A65; '71 A75
Triumph: '87 T140; '72 T150v
Re: 1955 BSA Bantam oil/ gas ratio [Re: Blown Income] #637052
01/25/16 4:25 pm
01/25/16 4:25 pm
Joined: Sep 2008
Posts: 720
Edgewater, Md
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Blown Income Online content OP

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Joined: Sep 2008
Posts: 720
Edgewater, Md
Thanks All!

I double checked the ratio of the tube on the filler cap (2 tube fulls per 1 gallon) which came out to 20:1 which I used using senthetic 2 stroke oil. I think it may be a bit rich as it smokes while idling. I think a 25:1 or 30:1 may be better but im going to run this gallon the way it is and check the plug.

So far on the little bit I rode it, it rides really good and has a decent amount of power for a plunger and only being a 125cc.

Last edited by Blown Income; 01/25/16 4:26 pm.

1955 BSA Bantam D1 Plunger
1956 BSA A10RR Street and LSR Bike
1961 BSA C15S
1966 BSA spitfire
1969 Triumph T100C
1970 Triumph TR6R
1972 BSA Lightning LSR Bike
1974 Triumph T150V
Re: 1955 BSA Bantam oil/ gas ratio [Re: Blown Income] #637058
01/25/16 5:02 pm
01/25/16 5:02 pm
Joined: Feb 2008
Posts: 4,129
New Jersey USA
Tridentman Online content

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New Jersey USA
My recollection from my Bantam days (many years ago now) was that the mixture recommended was 25:1.
However with improved oils then these days it is reckoned that a 50:1 mixture is fine as long as you are using synthetic two stroke oil.
And apparently -- very little smoke.
HTH

Re: 1955 BSA Bantam oil/ gas ratio [Re: Blown Income] #637088
01/25/16 8:28 pm
01/25/16 8:28 pm
Joined: Aug 2001
Posts: 2,402
SLO County, CA
D.Bachtel Online content
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Go 40:1 and use a modern blend like Maxima Castor 927.
Your friends will thank you for the pleasant aroma you leave behind on the trail.


Don in Nipomo


1956 Zundapp KS601EL
1960 Greeves Scottish/Hawkstone Velorex 560
1963 BSA Gold Star Spitfire
1964 Triumph T20SM
1965 BSA C15T
1966 BSA VE
1968 Bonham Tote Gote
1969 BSA VS
1970 BSA A65L (with a "Y")
1972 Husqvarna 450 WR
1986 Yamaha TT 225
1987 BMW K75C
Re: 1955 BSA Bantam oil/ gas ratio [Re: Blown Income] #637099
01/25/16 9:35 pm
01/25/16 9:35 pm
Joined: Oct 2001
Posts: 1,088
Sydney, Oz
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Shane in Oz Online content
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Originally Posted By Blown Income
Thanks All!

I double checked the ratio of the tube on the filler cap (2 tube fulls per 1 gallon) which came out to 20:1 which I used using senthetic 2 stroke oil. I think it may be a bit rich as it smokes while idling. I think a 25:1 or 30:1 may be better but im going to run this gallon the way it is and check the plug.

The early D1 Instruction manual quotes 3 filler caps per gallon (16:1) while running in, then 2 caps (24:1). That's Imperial gallons, not US, so will give a leaner mixture.
It also says that you can keep running on 16:1 if you like.

Around 30:1 on a more modern 2 stroke oil should work well. The art is to not run so lean that you seize or so rich that you're constantly fouling plugs.

Re: 1955 BSA Bantam oil/ gas ratio [Re: D.Bachtel] #637103
01/25/16 9:53 pm
01/25/16 9:53 pm
Joined: May 2005
Posts: 3,775
ohio
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ohio
Originally Posted By D.Bachtel
Go 40:1 and use a modern blend like Maxima Castor 927.
Your friends will thank you for the pleasant aroma you leave behind on the trail.


Don in Nipomo

That's what I always used in my 2 strokes, after a day out on the trails anything left in the gas can went in the lawn mower


When given the choice between two evils I picked the one I haven't tried before
Re: 1955 BSA Bantam oil/ gas ratio [Re: Blown Income] #637105
01/25/16 10:03 pm
01/25/16 10:03 pm
Joined: Aug 2001
Posts: 2,402
SLO County, CA
D.Bachtel Online content
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D.Bachtel  Online Content
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Posts: 2,402
SLO County, CA
I too have racing blowers and weedwhackers..

Re: 1955 BSA Bantam oil/ gas ratio [Re: Blown Income] #637217
01/26/16 6:15 pm
01/26/16 6:15 pm
Joined: May 2013
Posts: 4,664
Rotherham - S. Yorkshire
Allan Gill Online happy
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Rotherham - S. Yorkshire
I used to use about 170ml per British gallon. With synthetic 2t oil it will hardly smoke.


beerchug
Re: 1955 BSA Bantam oil/ gas ratio [Re: Allan Gill] #637241
01/26/16 10:24 pm
01/26/16 10:24 pm
Joined: Oct 2001
Posts: 1,088
Sydney, Oz
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Shane in Oz Online content
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Originally Posted By Allan Gill
I used to use about 170ml per British gallon. With synthetic 2t oil it will hardly smoke.

Somewhere between 25:1 and 30:1 then?

Re: 1955 BSA Bantam oil/ gas ratio [Re: Shane in Oz] #637269
01/27/16 3:06 am
01/27/16 3:06 am
Joined: May 2013
Posts: 4,664
Rotherham - S. Yorkshire
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Allan Gill  Online Happy
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Rotherham - S. Yorkshire
Originally Posted By Shane in Oz
Originally Posted By Allan Gill
I used to use about 170ml per British gallon. With synthetic 2t oil it will hardly smoke.

Somewhere between 25:1 and 30:1 then?


Could be, I never worked the ratio out. I just had a bottle marked up for ever half gallon of fuel in the tank, I emptied the bottle to that level. Bike ran great.


beerchug

Moderated by  Allan Gill, Jon W. Whitley 


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