Fuel mix ratio

[Virgoray248]

I have just bought a Greeves Scottish 1959 250 can anyone tell me the correct mix for two stroke oil please

[John Wakefield]

THis question has been asked many times, Villiers recommended 20 parts petrol to 1 part oil. Best to use a mineral grade two stroke oil like Comma 2 Stroke. https://www.commaoil.com/passenger-v...ducts/view/267 Modern synthetic oils at low ratios are not really suitable for old Villiers engines

[Virgoray248]

Thanks john

[John Pattinson]

I use a mineral 2 stroke oil at 32-1 for trials and road, no problems for 20 years.

[John Wakefield]

I use a mineral 2 stroke oil at 32-1 for trials and road, no problems for 20 years.

Thats your choice John, but Villiers recommended 20:1 so there must have been a reason, also the lower the oil content effects the mixture so carb may need re jetting on a leaner mix.
Is it really worth taking a risk on low oil ratios to save a few pence on oil? When giving advice on forums its always best to give the manufactures specifications so as there is no come back on the person (or indeed the club) should things go wrong.

[Stuart Baskill]

Thats your choice John, but Villiers recommended 20:1 so there must have been a reason, also the lower the oil content effects the mixture so carb may need re jetting on a leaner mix.
Is it really worth taking a risk on low oil ratios to save a few pence on oil? When giving advice on forums its always best to give the manufactures specifications so as there is no come back on the person (or indeed the club) should things go wrong.

I,m sure that I,ve seen it stated at 16/1 for self mixing oils in a Villiers book and not just for running in.As you say oil is cheaper than a rebuild.

[John Wakefield]

Indeed so Stuart. in the 4T handbook (and I am sure also in the 9E 32A etc handbooks) Villiers stated SAE30 oil at 20 to 1, but if using a self mixing two stroke oil (which has an additive to aid mixing) the ratio should be 16 to 1.
Not sure that self mixing two stroke oils are readily available in this day and age of the injected oil system used on most modern two strokes. The Comma oil mentioned is a standard straight 30 grade.

[350biker]

I have been running my 32A Scottish on 30-1 Comma Mineral oil and am appalled by the amount of black oil blown out of the exhaust joints and end pipe. I can not believe what the bike would look like running 20-1 or 16-1! Spoke to many 32A riders at today's Poacher's Pre65 Trial in Lincolnshire and the collective advice was almost unanimously to go Full Synthetic at 50-1. If you slavishly follow the Villers handbook recommendations you will end up, like I did, with a sticky clutch (straight 30 recommended). Thanks to the sage advice from the GRA stand at the Stafford Show went to a modern Light Transmission oil with clutch plate release additives. Problem solved. Oil technology has moved on greatly since Villers made their little engines.

[John Wakefield]

I found this comment from a previous thread originally published on https://cybermotorcycle.com/components/premix.htm

Two-Stroke Oil Premix Ratios

The following is extracted from the Villiers forum, and is applicable to most twostrokes built before the mid-1960s.
As far as premix goes the 16:1 is still correct for running in a new engine and you can then cut down to 20:1 thereafter. Villiers began to recommend 20:1 in the early 1950's when self mixing two-stroke oil first became available. This is appropriate for both the engines you have . You will be told you can cut down the oil a lot if you use a modern synthetic oil. Do not do so. Synthetic oils are meant for modern two-strokes designed to modern standards. The older design of Villiers engines means they need a lot more oil. They are the last of the early design of two-stroke, for best results stick to 20:1. Because they are a slow revving engine compared to later two-strokes a two-stroke oil suitable for lawnmowers, chainsaws, etc, is fine for them. It will smoke when it is cold, it will smoke if you only travel short distances but it will stop smoking when it is hot and stop smoking if you ride it any distance. If a pre-mix two-stroke is smoky all the time its the riders fault not the bike. It is not being ridden far enough or long enough to keep clean. For years I rode two-strokes to work and they would get smoky in all the stop/start traffic. When it got too bad I would go for a fast ride on the local freeway which would clear the exhaust of the oily build up. The bike would then run sweetly for another month or so and I would then repeat the exercise.

If you had an old bike with an ordinary four-stroke engine and someone told you it would run better if you only half filled it with oil you'd think they were nuts. Cutting down on the oil in premix is exactly the same thing and just as foolish.

Do not bother with premium grade fuel. Again, because these engines were designed in the days of low octane fuel there is no point in using anything up market. Standard unleaded fuel of today is far better than anything available when they were new. Also, they are unable to take advantage of anything better so it is just a waste of money and you won't get any better performance. Always use unleaded. Leaded fuels can quickly foul up the spark plugs on Villiers engines and be a real nuisance. The introduction of unleaded fuel was a real bonus for two-stroke riders as it got rid of a lot of spark plug problems.

by 33d6

[IanCordes]

I am guessing the issue here is that trials bikes never do have a really good road run to burn off all the oil. They stop start in short bursts, and are rarely revved very high. This article refers specifically to road machines, which is your area of expertise, John. 'It is not being ridden far enough or long enough to keep clean'. Therefore maybe it is not a one-size-fits-all, and listening to the experienced trials riders is the way to go. Having said that, Virgoray, what use will you be putting the bike to? Have you bought it to compete in trials, or just a bit of light road use? I do agree that the design of these engines lends themselves to requiring thicker oil in greater quantities than modern 2-strokes.

[Brian Catt]

Yes, we are talking horses for courses here. Trials, Scrambles and Road all need somewhat different approaches. As Ian says, Trials bikes are rarely run hot enough to burn off the muck, Scrambles bikes often have huge fins and it then depends on mud cover as to the cooling efficiency. Road bike used for commuting will be different to a bike that is used on longish journeys. Mix and match to your circumstances. As an aside, a contact of mine who resides in Canada, but of German extraction uses a 100:1 mix ratio in his "Vintage" Hercules Enduro bikes. We cannot seem to get that oil here, but I'm looking into it!

[Jeff Morgan]

Everyone will have their own take on this, and as has been pointed out the application really dictates what the 'right' answer is, but it should be understood that the technology in modern, semi or fully synthetic premix specific two stroke oils is way ahead of what was available when Villiers designed their engines. Given that the oil is distributed as a fine mist in atomised fuel, its the ability to cling to bearing surfaces that dictates whether it works or not.

I've run my various 32A & 37A engines on 50:1 semi synthetic premix oils since I 'regressed' from Jap and Spanish machinery to pre 65 in 2005, used for trials and some speed events, with no problems, and an air cooled motor can get plenty hot enough riding all day in thick South East mud. I used the same oil at the same ratio in Japanese water cooled enduro machinery.

As regards premium or regular unleaded fuels, the addition of the dreaded ethanol raises the Research Octane Number to meet specs, which was one of the functions of the lead as an additive, but it actually reduces the amount of energy released, so for a given amount of power you need a higher octane number. Probably not too much of a problem on a standard Villiers motor, but definitely a problem on a performance or tuned one. Plenty of info about that on the modern trials, enduro and moto-x forums. I use premium 97 RON or higher.
Plug whiskering was a problem when the ash content of the burnt oil was high, no longer the case with modern oils, not sure lead had an influence on that.

That's my 3 ha'ppence worth, you pays yer money and takes yer choice!

Jeff

[IanCordes]

Out of interest, when I was racing 250 MZ's 3 or 4 years ago, bearing in mind they are 250 single air-cooled 2-strokes, we never used a petrol/oil mixture leaner than 25:1 using fully synthetic racing oil. at £25 a litre. Some used 20:1. You could always tell when the MZ's were about to go out on track from the smoke rising from the holding area! Once on track though the smoke was minimal. These were tuned to make in the region of 30bhp, so in good Silverstone territory, but on Moto3 slicks, and disc brakes. Usual fuel was a 50/50 mix of Tesco 99 ron super-unleaded and 100 octane low-lead ethanol-free avgas.

Ian

[John Wakefield]

As is usual with these threads different owners have their own preference. Getting back to Vigoray248's post. I gave the Villiers official spec on this to be in line with GRA guidelines, we dont want any come back from someone causing damage to their bike and maybe themselves when pursuing modifications outside of manufacturers specifications. This subject has been raised many times on this forum and I would normally have posted a link to a previous thread. But as the search engine on this new forum is not always picking up previous threads, particular older ones then I replied as I saw fit. The fact is that if Vigoray248 sticks to the oil/petrol ratio specified by Villiers then he will not do any damage. I would suggest the Vigoray248 obtains a Villiers users manual for his engine, as all info is in there to maintain it, one can be downloaded here https://www.manualslib.com/products/...2a-6917899.htm
I will leave it there.