sinkingfast
Seaman Apprentice
- Joined
- Dec 31, 2003
- Messages
- 34
THE STANDARD TWO STROKE RULES.<br /><br />There has always been a rule of thumb for motors of all types.<br />If it dont need fixing
then dont fix it<br /><br />I have no problem with that but by sheer logic, it implies you should only fix it when it breaks. Great
try telling that to the guy that just seized his motor 10 miles out through nothing more than bad set up. Now as I said before, a lot of what I say will be common sense, and if you already do all that, then good. But, if I can help just one of you with a bit of information that saves a breakdown, then I am happy.<br /> <br />Ok, your engine manufacturer spent thousands of hours and serious money developing the motors we use. Some good ones and some poor ones, but either way, the manufacturer assumes that certain standards will be used.<br /><br />Let us see if we can establish the baselines for your TWO-STROKE motor.<br /><br />FUEL SUPPLY<br /><br />Most engines will use unleaded gasoline and all the standard carburation settings, oil burn ratios, compression ratios will take that into consideration. The number of the octane rating of the fuel, gives a standard, a known performance. The higher the octane number, the cooler it runs. The cooler it runs, the better the efficiency. Now all the manufacturers have based their settings on a specified grade of fuel. They know what their engine needs to get the best out of it, and they tell you. Stick to it.<br /><br />Playing with fuel additives or higher graded racing fuels to supposedly increase the performance to staggering levels is a waste of time and effort if the factory base settings are left as standard. What it does do however is make the burn coefficient change and it runs slightly cleaner and cooler. If a higher graded unleaded is used every now and then through a season, the effect will be to keep the engine crisp and the oil tartar deposits low. <br /><br />All fuel deteriorates with age, and the racers know that fuel that is more that 3 months old, even when stored in an airtight container, has lost is standard and should not be used. Most use this removed fuel for use in lawn mowers and 4 stroke engines where there is greater latitude on the fuel.<br /><br />Fuel tanks stored empty will raise some condensation and sometimes rust. Flush the tanks out at the start of the season where possible with clean fuel. A small shot of two stroke oil directly into the tank at the season start will also aid the motor settle down and build up the oil barriers faster.<br /><br />For the guys that use carry tanks, they rely on small filters in the line to stop debris but not water. They remove the tank to fill it but leave the fuel line and bulb in place. I can see no reason why they dont fit a water separation filter somewhere between the tank and priming bulb. <br /><br />To test the priming bulb, squeeze the line between the bulb and motor with a pair of grips.<br />When you are sure the line is blocked off, pump the priming bulb. It should go rock solid.<br />If it doesnt, replace it. If it is more than 4 years old, you should consider replacing it anyway.<br /><br />The fuel pump on the motor is often activated by vacuum. Look at the pipes on and around the fuel pump. If the small pipes show signs of cracking at the ends, its time to replace them or at least cut them back and re site them.<br /><br />For the more adventurous of you, look at the fuel pump diaphragm. Take the cover off the pump and simply look at the rubber diaphragm. If it is smooth in appearance, that is fine. If however it looks as though it is deformed and stretched change it. Every 4 years it is worth a replacement anyway. It is designed to be changed easily and so dont be afraid to look.<br /><br />The fuel carries the lubrication in the earlier premix motors;<br />Compromise the fuel, you compromise the lubrication.<br />Use stale fuel, power goes down, temperature goes up.<br />Temperature goes up, you compromise the lubrication again.<br /><br />Two stroke motors work best with a small amount of burnt carbon on the piston crown. Obsessive cleansing or polishing of the piston crowns can also lead to problems. A shinny metal surface of a piston crown being hit by petrol vapour leads to the fuel mixture condensing and turning back into liquid on contact with it. (similar in effect to breathing onto a glass surface). The petrol literally runs off the piston, running down the sides and onto the rings, washing off all the lubricant on them in the process. Start the engine with a dry patch on the ring/cylinder contact area leads to premature failure. This can be true with four-stroke engines that have been enthusiastically tuned.<br /><br />I intend to go into the fuel problems later that are associated with engines standing for periods of time and how to deal with them. We can cover reading the burn patterns, oil lubrication efficiency if you would like that.<br /><br />OIL LUBRICATION <br /><br />In general use today, there are 2 types of two stroke lubrication systems.<br />The pre-mixed petrol/oil type, and the auto-lube systems. Each manufacturer specifies an oil grade but almost all of the modern oils are suitable within the same grade.<br /><br />For the premix guys, did you know that storing your oil wrongly could lead to major engine breakdowns? If the stored premix oil is placed on the floor and then subjected to severe frost, it changes its properties. When the season starts, you mix the oil and use it and it is fine for a while, but the oil components literally separate apart from within the petrol/oil mix. Re-mixing it will not help. The lubrication is compromised and so one minute you are smoking; next minute crank and rod bearings have gone. If in any doubt at all, dont use frosted oil. (So far we have not seen this problem with the autolube guys.)<br /><br />Mixing a little extra oil into the fuel just in case leads to more oil but less combustible fuel, so more temperature, actually compromising the efficiency of the oil. Extra temperature leads to extra tartar and resin forming round the piston rings, and lowers the effectiveness of the ring.<br /><br />The manufacture will have settings for the auto oil mixing pumps. By the same token, the factory settings and recommendations are set for a reason. Check them and never assume they dont alter, they do.<br /><br />Many autolube engines now have a simple failsafe warning system on them to prevent the level getting too low. It costs nothing to check the connections and trip the sensor with your finger to see if it is functioning.<br /><br />Basics I know<br />How many times have I seen seized motors, bearings gone and ruined motors that could have been avoided?<br /><br />I will tell you
Too many!<br /><br />Give me some feedback as to the level of information you require so I can build that into the next instalment.
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