PURCHASE GUIDE
TWO-STROKE ENGINES
The two-stroke engine has higher power and costs less to manufacture than the four-stroke, but it is less efficient and the post-combustion emissions are more polluting. This type of engine has long been the exclusive preserve of mopeds and racing motorbikes. For the last decade or so, there has been a revival of interest in the two-stroke engine for cars (e.g., the Renault Powerful prototype).
Principle of the two-stroke engine:
A complete combustion cycle takes place in just two linear piston movements (back and forth), compared to four on a four-stroke engine.
Lubrication of the two-stroke engine:
In most two-stroke engines, the bottom end does not contain any oil. The moving parts are lubricated by the passage of the fuel/combustion agent mix, therefore containing a small percentage of oil. The oil is therefore consumed by combustion and ejected through the exhaust. The mixture has to be made up when filling the fuel tank. Nevertheless, there are alternative lubrication systems for two-stroke engines, such as separated oiling.
Type of lubricant and two-stroke oil standards:
There are several types of Technilub oils for two-stroke engines:
Semi-synthetic oil: This is composed of a mixture of mineral oil and synthetic oil. It is frequently used for two-wheelers and gardening machinery.
However, it offers inferior performance for racing bike engines.
Synthetic oil: This is 100% synthetic. This is the technology that offers the best performance. This type of lubricant is intended for racing bikes and extreme usage conditions.
As well as the grades of performance linked to their types, the oils have to satisfy additional requirements: the specifications.
The API, for example, demands increased performance standards for its oils from one publication to the next, in order to improve behaviour at higher temperatures and solubility in petrol, to give off a minimum of fumes, and to produce smaller quantities of deposits.
The Japanese standards publisher, JASO (a benchmark for motorbike lubricants), calls for the same kind of developments as demanded under API standards, but even more stringent. The required performance upgrades are therefore built around anti-deposit and anti-fume aspects, necessitating successful completion of lubrication and detergent tests.
Usage tips:
→ If large quantities of white or blue smoke are emitted from your engine, try readjusting your mix. You might not be using the right quantity of oil.
→ Whatever the type of lubrication (mixed or separated), never forget to include the oil, or your engine may seize up.
→ Petrol contains additives that degrade the quality of both oil and mix over time. You are advised to drain and replace the mix after a month of disuse.
→ To avoid stagnation of the oil in the bottom of the tank and in order to have a homogeneous mix, remember to mix the content of the tank by shaking your bike or machine a little.
→ Take care not to pollute your mix with other fluids/liquids (e.g. water) and with any deposits that may clog your system.
→ Recommendations will vary from model to model. Always remember to check your servicing manuals.
Our measuring caps are graduated and can hold up to 20 ml of oil.
By way of example, a 2% mix represents one full cap (20 ml) for 1 litre of petrol.
Another example: a 3% mix represents 7.5 caps (150 ml) for 5 litres of petrol.