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MOD / Rider / Mechanic
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My thoughts, you can not go wrong using semi synthetics, if you have concerns. The best in my opinion is a full synthetic. make sure you keep everything super clean where you put in the oil. My Yamaha DT had an oil injection (Was a weak set up anyway) and it plugged up with crud and eventually failed to inject the oil causing me to have to rebuild it for the first time and converted it to a premix and then my almost quarterly teardown ensued due to riding a mix of on the street, highway and off-road. I believe in this matter @Trials could be on top of his game on this subject due to the type of bikes he rides regularly.

On my 2 stroke tools, ie. chainsaw, weed eater, blower I use synthetic and they seem to run better.
 

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Semi-syn oil sucks because they can add 1% syn and still claim it is semi-syn to make you not have a clue. The main difference in syn and conventional oil is the amount of heat the oil stands before it carburizes and OTC syn will go almost double what conventional will. The main problem with 2 strokes is HEAT (why the compression is not as high) and what causes them to seize. Why I used to loosen them up when building race ported engines. I also built and modded the oil pumps (Yamaha and Mikuni) for more output.

True syn oil also holds film strength far better than conventional at much lower weights. Why you want it for oil injection during the winter.
 

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Wot AMC said above. More horsepower, creates more heat. Some engines in the early days, did not dissipate ( get rid of ) heat evenly, and some bits heated up quicker than others. End result was some 2 strokes had a bad habit of seizing.
With liquid cooling, there was no gain in horsepower initially, but the horsepower did not tail off. Then they could increase the horsepower, and keep the engines reliable. A lot of 2 strokes went very fast, before all these modern synthetic oils were available. 250cc bikes doing 125 mph with 45hp. 350 bikes doing 148. All air cooled, and not seizing.

Forgot. Some pistons had quite a bit of variance in size, even when stamped with the same number. So we check the fit of all pistons with a long feeler gauge. 2 thou was common. Sometimes we ran them for a while, and sanded down the high spots on the pistons. I am running yuse thru a range of years, later sixties to mid seventies. UK
 

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Ace Tuner
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Race gas not needed for 2-stroke engines?
Back in the mid 1980's we tried and tried to run pump gas in our modified RZ350 endurance bike but no dice. It was not a tuning, ignition timing or spark plug heat range problem. It was detonation caused by insufficient octane. You could see it on the spark plugs. Race gas stopped the detonation problem that was occurring at high RPM / peak power output. Race fuel cost us about 3 ~ 4 times more than premium pump gas. We were not happy about having to spend even More Money on fuel.
My RD350 has to have race fuel too.

Fun Fact:
A modified RZ350 gets really bad gas mileage when running flat out all day. Eight hours of that makes for a very real fuel bill.

S F
 

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Depends on how much compression you have, less advance with more compression. I used to do 155 psi compression on Kaw 3 and if you had really good double or even triple squish angles you could go up to 160 maybe 165. Water cooling you got 165 and more if the cooling really worked but 200ish was the limit back then. Nothing like the 300 psi a 4 stroke can get.

The more oil you used the higher the detonation, oil being a detonation maker and why you want no oil in max effort engines like cars use. Dennis Dean of Kaw 3 race fame used to say you sneak up on the power by slowly dropping the oil and fuel amounts and using the coldest plug the engine would fire to get closer and closer to lean best hp. numbers and how the 140 hp. Mach IV 750-3 (actually 800 cc.) race engine was done. Race fuel was a must.

If you had too hard an angle on the chamber rear cone or the stinger ID was too small the engine would tend to overheat.

I remember the instructions in any hi-perf 2 stroke manual to run the engine a short period then yank top end to take all pistons and sand them at the polished areas on skirt where localized load was the highest as the seizure would later form there. If you loosened the whole thing up you had to keep watch for skirt cracking too. You had to have really nice port edge dropoff chamfers too, the radiusing there had to be gradual to not hang up rings and skirt edges. Most pistons I clearanced at ,002" but bigger like 750-3 I would get .0025" or even close to .003".
 

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2002 Honda VTX, 1995 Ducati, Harley panhead in a box
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Hi. I own a 1999 50cc LC Malaguti F15 Firefox and I'm trying to figure out which is the best type of 2 stroke oil to use. Mineral, semi synthetic or full synthetic?

Any help would be appreciated. Thanks
Trials is right, Amsoil is what I use also, in everything. Original clutch in my 60k miles 2002 VTX, etc.
My premix, 2 stroke Weed Wacker is 12 years old, is abused, and the compression feels like new. Amsoil is more expensive, however, Oil is cheap compared to the oil wetted parts it protects.
 

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OIL IS THE CHEAP MECHANIC .
 
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