Oil/mix
- Thread starter canalcat
- Start date
- Status
I believe you want the minimum amount of oil needed to lubricate the engine, with erring on the excess side to be safe and protect the engine.
the oil you use will effect the ratio, most use a synthetic and run around 40 or 50 to 1 once broken in. I use amsoil synthetic which is supposed to provide good lubrication up to 100:1. I am running 80:1 and will stick with that. I will pull the head off once in awhile and see how it looks.
the less oil in the mix the stronger combustion, as the oil doesn't ignite or burn, but coats all parts it comes into contact with. but try to run too rich (too little oil) and you'll just seize the engine.
thats what i've picked up so far.
the oil you use will effect the ratio, most use a synthetic and run around 40 or 50 to 1 once broken in. I use amsoil synthetic which is supposed to provide good lubrication up to 100:1. I am running 80:1 and will stick with that. I will pull the head off once in awhile and see how it looks.
the less oil in the mix the stronger combustion, as the oil doesn't ignite or burn, but coats all parts it comes into contact with. but try to run too rich (too little oil) and you'll just seize the engine.
thats what i've picked up so far.
sbest
Active Member
I followed the Grubee instructions and mixed my oil up rich at 20:1.
Here is what my cylinder head looks like after only 3 tanks of gas:
Even in the blurry cellphone pict, you can see the chamber is well carboned up with maybe 6 hours running on it.
Here is a couple engines that had many, many hours of 50:1 synthetic and one that didn't:
The one on the right has several thousand kms of highway running on it with a lean fuel mixture and Ipone 50:1 oil.
Look at the gasket to get a feel for how long it had run.
The one on the left was mainly dirt riding, 40:1 and 50:1 but with a richer fuel mixture.
The middle cylinder head was off a parts engine, history unknown.
From my experience with my KTM 125 you want the minimum amount of oil and fuel.
https://scontent.fyhz1-1.fna.fbcdn....=daff096a46f319483cd2fed2cdea38d5&oe=56DC991A
Here is what my cylinder head looks like after only 3 tanks of gas:
Even in the blurry cellphone pict, you can see the chamber is well carboned up with maybe 6 hours running on it.
Here is a couple engines that had many, many hours of 50:1 synthetic and one that didn't:
The one on the right has several thousand kms of highway running on it with a lean fuel mixture and Ipone 50:1 oil.
Look at the gasket to get a feel for how long it had run.
The one on the left was mainly dirt riding, 40:1 and 50:1 but with a richer fuel mixture.
The middle cylinder head was off a parts engine, history unknown.
From my experience with my KTM 125 you want the minimum amount of oil and fuel.
Fabian
Well-Known Member
The engine will take anything you can throw at it, with an optimal air fuel ratio, and 25:1 so long as it is not over revved.
KCvale
In memory of KCvale 1959 - 2019
I agree.
Though I don't go the Amsoil rout due to cost, I run decent 2-stroke synesthetic at 32 parts gas to 1 part oil (32:1)
In a one gallon full can of fresh gas, just add 1/2 of cup of oil (4oz) to it.
Fill you tank from it until it's empty and start again.
Easy and always correct.
Using less oil is better if you can, all too much does is make a mess and hamper performance.
D
Deleted member 12676
Guest
interesting article recommending synthetic oil only for 4 stroke engines:
http://www.2strokeheads.com/OIL-TECH.htm
1) BRP/ Ski Doo quit recommending synthetic oil to be used in their snowmobile engines in 2006.
2) Synthetic Oil can NOT be used to properly seat piston rings. This is a KNOWN fact to the manufacturers of synthetic oil. MOST have a non-synthetic "Break-In" oil that is used to properly break-in a new engine.
3) AND the #1 reason why a synthetic oil is not as good in a 2 stroke engine--> IT DOES NOT FULLY COMBUST! (and so does not contribute to engine power as normal oil does)
http://www.2strokeheads.com/OIL-TECH.htm
1) BRP/ Ski Doo quit recommending synthetic oil to be used in their snowmobile engines in 2006.
2) Synthetic Oil can NOT be used to properly seat piston rings. This is a KNOWN fact to the manufacturers of synthetic oil. MOST have a non-synthetic "Break-In" oil that is used to properly break-in a new engine.
3) AND the #1 reason why a synthetic oil is not as good in a 2 stroke engine--> IT DOES NOT FULLY COMBUST! (and so does not contribute to engine power as normal oil does)
D
Deleted member 12676
Guest
interesting side note:
wikipedia says that semi-synthetic oil has less than 30% synthetic. So I did some math and figured that if regular oil needs to be mixed at 20:1 and synthetic at 50:1 then a semi-synthetic with 25% synthetic oil needs to be mixed at 25:1
I use semi-synthetic and have noticed accelerated wear while using it at a ratio of 30:1 so a few weeks ago I started mixing it at 25:1 (just guessing at what the best ratio is without having done the math)
wikipedia says that semi-synthetic oil has less than 30% synthetic. So I did some math and figured that if regular oil needs to be mixed at 20:1 and synthetic at 50:1 then a semi-synthetic with 25% synthetic oil needs to be mixed at 25:1
I use semi-synthetic and have noticed accelerated wear while using it at a ratio of 30:1 so a few weeks ago I started mixing it at 25:1 (just guessing at what the best ratio is without having done the math)
Fabian
Well-Known Member
The Chinese 2-stroke bicycle engine is made from the lowest grade aluminum; exhibiting very poor thermal stability, which allows for a lot of blow-by as the cylinder bore does maintain proper bore concentricity as it heats up; with the piston rings unable to properly provide good sealing between ring face and the bore face.
The only thing that can help rectify this situation is the hydrodynamic barrier of 2-stroke oil; being your greatest friend at preventing blow-by.
Although air-cooled specification mineral oil does not like to burn, and also lowers octane rating slightly (both of which are factors that reduce power) the overall gain by using an higher oil/fuel ratio exceeds the previously mentioned contributors to power loss because the piston ring to cylinder wall oil barrier reduces blow-by; thereby maintaining higher cylinder pressure, which yields a net gain in power, but more importantly, an improvement in low and midrange torque, because the lower the rpm in such a situation, the greater the time available for blow-by.
Another important aspect of oil in these 2-stroke Chinese bicycles is thermal mitigation, as it allows improved cooling of hot spots (due to poor metallurgy and poor thermal stability); carrying that heat out the exhaust, instead of having it build up at a localised point; being the starting location for premature engine failure.
In these low cost engines, the third function of 2-stroke oil is lubrication, but the primary function is hydrodynamic sealing, then heat rejection, and lastly the function of lubrication.
When running 50:1 or 100:1, you have just lost the 1st and 2nd functions of 2-stroke oil in the Chinese 2-stroke bicycle engine.
Having said that, if you are just putt-putting around, without the engine being heavily loaded up, and having an optimal air/fuel ratio, i would recommend 40:1, as the engine will not need higher levels of oil to cope with heat rejection or lubricity, and the hydrodynamic barrier is of no great importance in such a circumstance.
But if you are using the bicycle as a work horse, then you need to operate the engine with consideration to the above mentioned information.
http://motoredbikes.com/threads/more-heavy-haul-australian-style.46503/
The only thing that can help rectify this situation is the hydrodynamic barrier of 2-stroke oil; being your greatest friend at preventing blow-by.
Although air-cooled specification mineral oil does not like to burn, and also lowers octane rating slightly (both of which are factors that reduce power) the overall gain by using an higher oil/fuel ratio exceeds the previously mentioned contributors to power loss because the piston ring to cylinder wall oil barrier reduces blow-by; thereby maintaining higher cylinder pressure, which yields a net gain in power, but more importantly, an improvement in low and midrange torque, because the lower the rpm in such a situation, the greater the time available for blow-by.
Another important aspect of oil in these 2-stroke Chinese bicycles is thermal mitigation, as it allows improved cooling of hot spots (due to poor metallurgy and poor thermal stability); carrying that heat out the exhaust, instead of having it build up at a localised point; being the starting location for premature engine failure.
In these low cost engines, the third function of 2-stroke oil is lubrication, but the primary function is hydrodynamic sealing, then heat rejection, and lastly the function of lubrication.
When running 50:1 or 100:1, you have just lost the 1st and 2nd functions of 2-stroke oil in the Chinese 2-stroke bicycle engine.
Having said that, if you are just putt-putting around, without the engine being heavily loaded up, and having an optimal air/fuel ratio, i would recommend 40:1, as the engine will not need higher levels of oil to cope with heat rejection or lubricity, and the hydrodynamic barrier is of no great importance in such a circumstance.
But if you are using the bicycle as a work horse, then you need to operate the engine with consideration to the above mentioned information.
http://motoredbikes.com/threads/more-heavy-haul-australian-style.46503/
D
Deleted member 12676
Guest
I personally hate all the smoke that two strokes on regular oil make which is why I use semi-synthetic. At 25:1 if makes some smoke but not enough to be offensive in this world of clean running 4 strokes.
butre
Well-Known Member
I don't mind the smoke, but I'm sure there are some people that watch me zip by leaving a huge cloud and shake their heads.
- Status
