Cut4fun
Redneck Chainsaw Repair
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About Oil injection Oils and Smoking - It's important to understand that there is no such thing as a "straight petroleum" oil, nor a "synthetic" oil.... those are just industry "buzz" words. With the exception of castor bean oils, all 2stroke oils are a mixture of the chemical components needed to do the respective job at hand .... and it has been that way for many decades. In the 70's a very common component of most 2stroke oils was "bright stock". Bright stock was very inexpensive, and offered decent lubrication qualities, but it contributed greatly to excessive smoking, no matter how lean the oil ratios got.
Nowadays, most "quality" two stroke oils have long since replaced bright-stock with Poly-Butane. Poly-butane is roughly triple the cost of bright-stock, but it smokes much less, and still offers great lubrication qualities. All that said, there are still several 2stroke oil makers that use bright-stock instead of Poly-butane ... simply to cut costs. The bummer is that there is no labeling that allows you to know which is being used, and very few oil makers that will give you an honest answer if you ask them. This same scenario applies for several other primary components of current 2stroke oils. But There's more.....
99% of all two-stroke oils containers say "smokeless" or "low smoke". The truth is that there is no engineering nor industry standards for varying levels of "smoke-free-ness". The oil makers can print anything they want on the bottles without ever having to meet or comply with any industry standards or limits.
As a result of all this, we use exclusively Maxima Oils products, because the folks at Maxima are very open and up-front about what their oils are made of. In the genre of Maxima 2cycle oils, their 927 castor oil is by far the best for high-temperature competition engines. However if you try to use this castor oil in a street (premix) application, you can experience excessive smoking in engines that do not run particularly hot. The most smoke-free oil that Maxima makes is their "Super M" which comes in a premix and oil-injection viscosity. Super M contains no bright-stock, and instead uses the much more smoke free poly-butane. Maxima also offers a purpose made "scooter" oil that is slightly more smoke free than Super M, however this scooter oils doesn't offer the lubrication needed for a high temperature air-cooled vintage engine.
Piston Seizure Vs Piston Scoring - Piston “seizure” and piston “scoring” are two different stages of the same problem. When the oil film on a cylinder is momentarily burned or brushed away, the bare metal surfaces of the piston and the cylinder wall will actually touch. When this happens, there is a sort of scraping that takes place between them. If the oil film is quickly resumed, the marks from this scraping will often remain on the piston and (or) the cylinder wall. A momentary scraping or "scoring" seldom causes any permanent or performance robbing damage. In a momentary scoring event like this, no significant damage takes place because the oil film is resumed before the piston and cylinder have a chance to start exchanging material onto one another.
Scoring is commonly seen on the piston face directly below the piston ring end gaps. The blast of combustion can get between the large end gap of a worn out ring and burn the oil off the piston and cylinder in that area...Hence the surface scoring. In most cases, score marks can simply be sanded off of the piston and cylinder. However when ever you see scoring, it's a good idea to find the source so that it doesn't develop into a full blown seizure.
Piston seizure is a case of scoring where the oil film does not immediately return. After a few moments of constant scoring, the piston and cylinder will scratch each other hard enough to remove material from each other. This floating material grinds itself into the piston and the cylinder as it continues to grow in size. As this snowballing material grows, it will drive the opposite side of the piston against the cylinder wall with a pressure so terrific that scoring on the other side of the piston begins to take place. While all this is going on, your engine is still running wonderfully at full throttle. However if there is a momentary lifting of the throttle, the force of this scoring can cause the piston to “seize” in the bore. In a “light seizure” event like this, the rings often escape any damage, and the engine will easily re-fire as soon as the engine cools down slightly.
The death blow of a “power-on” seizure comes when the mass of material between the piston and the cylinder wall finds it's way to the piston rings. This nearly molten mixture of aluminum and iron can lock the ring in it's groove. This ring locking, not the piston surface scoring, is what actually causes your engine to quit when you experience a “throttle-on” seizure. When the piston ring becomes locked back in it's groove, it's incapable of providing compression sealing against the cylinder wall. This instant loss of compression, while the engine is at speed, causes a dramatic loss of power. That power loss, along with the added drag of the badly scoring piston, makes the engine quit or lock up in a nanosecond. In fact this entire seizure process, from the first scoring scratch to the piston locked solid, takes less than a second at full rpm. In such a failure, a single cylinder
Nowadays, most "quality" two stroke oils have long since replaced bright-stock with Poly-Butane. Poly-butane is roughly triple the cost of bright-stock, but it smokes much less, and still offers great lubrication qualities. All that said, there are still several 2stroke oil makers that use bright-stock instead of Poly-butane ... simply to cut costs. The bummer is that there is no labeling that allows you to know which is being used, and very few oil makers that will give you an honest answer if you ask them. This same scenario applies for several other primary components of current 2stroke oils. But There's more.....
99% of all two-stroke oils containers say "smokeless" or "low smoke". The truth is that there is no engineering nor industry standards for varying levels of "smoke-free-ness". The oil makers can print anything they want on the bottles without ever having to meet or comply with any industry standards or limits.
As a result of all this, we use exclusively Maxima Oils products, because the folks at Maxima are very open and up-front about what their oils are made of. In the genre of Maxima 2cycle oils, their 927 castor oil is by far the best for high-temperature competition engines. However if you try to use this castor oil in a street (premix) application, you can experience excessive smoking in engines that do not run particularly hot. The most smoke-free oil that Maxima makes is their "Super M" which comes in a premix and oil-injection viscosity. Super M contains no bright-stock, and instead uses the much more smoke free poly-butane. Maxima also offers a purpose made "scooter" oil that is slightly more smoke free than Super M, however this scooter oils doesn't offer the lubrication needed for a high temperature air-cooled vintage engine.
Piston Seizure Vs Piston Scoring - Piston “seizure” and piston “scoring” are two different stages of the same problem. When the oil film on a cylinder is momentarily burned or brushed away, the bare metal surfaces of the piston and the cylinder wall will actually touch. When this happens, there is a sort of scraping that takes place between them. If the oil film is quickly resumed, the marks from this scraping will often remain on the piston and (or) the cylinder wall. A momentary scraping or "scoring" seldom causes any permanent or performance robbing damage. In a momentary scoring event like this, no significant damage takes place because the oil film is resumed before the piston and cylinder have a chance to start exchanging material onto one another.
Scoring is commonly seen on the piston face directly below the piston ring end gaps. The blast of combustion can get between the large end gap of a worn out ring and burn the oil off the piston and cylinder in that area...Hence the surface scoring. In most cases, score marks can simply be sanded off of the piston and cylinder. However when ever you see scoring, it's a good idea to find the source so that it doesn't develop into a full blown seizure.
Piston seizure is a case of scoring where the oil film does not immediately return. After a few moments of constant scoring, the piston and cylinder will scratch each other hard enough to remove material from each other. This floating material grinds itself into the piston and the cylinder as it continues to grow in size. As this snowballing material grows, it will drive the opposite side of the piston against the cylinder wall with a pressure so terrific that scoring on the other side of the piston begins to take place. While all this is going on, your engine is still running wonderfully at full throttle. However if there is a momentary lifting of the throttle, the force of this scoring can cause the piston to “seize” in the bore. In a “light seizure” event like this, the rings often escape any damage, and the engine will easily re-fire as soon as the engine cools down slightly.
The death blow of a “power-on” seizure comes when the mass of material between the piston and the cylinder wall finds it's way to the piston rings. This nearly molten mixture of aluminum and iron can lock the ring in it's groove. This ring locking, not the piston surface scoring, is what actually causes your engine to quit when you experience a “throttle-on” seizure. When the piston ring becomes locked back in it's groove, it's incapable of providing compression sealing against the cylinder wall. This instant loss of compression, while the engine is at speed, causes a dramatic loss of power. That power loss, along with the added drag of the badly scoring piston, makes the engine quit or lock up in a nanosecond. In fact this entire seizure process, from the first scoring scratch to the piston locked solid, takes less than a second at full rpm. In such a failure, a single cylinder
