What's better about 32: 1 than 40:1 I'm thinking about goin bak to 40:1 what kind of change in jetting would I need to make?
32:1 is the best option for motors around 200cc, because it delivers sufficient oil for optimum lubrication.
It is really about size and revs that determine the amount of oil needed for perfect lubrication.
The smaller the engine components are, the higher revs can be produced, therefore leaving less time for oil to be dropped out of suspension and collected in the crankcase.
A 50cc engine requires much more oil in the mix than a 400cc engine, simply because the smaller volume of oil which passes through the carby, and the amount of time taken for the oil to come out of suspension.
It is not the oil in the premix that provides the lubrication, but the amount of oil which comes out of suspension and collects in the bottom of the crancase.
This oil is then picked up by the revolving crank and splashed around the motor.
It is correct that a higher concentration oil will increase compression, but the extra oil in the mix will require a larger main jet to compensate for the lower amount of fuel.
For example, changing from 32:1 to 25:1 will need a size larger main jet because , more oil = less fuel.
Some oils can be used at lower concentrations because of their lubrication qualities and their viscosity. They will provide the correct lubrication due to their design and application.
I hope I have explained it so you can understand, but the smaller the motor the more oil you need to use in the premix.
I don't understand it myself. I've go a yamaha kt100 2stroke on my gokart and everyone has told me to run it at 16:1. My blaster and my cr125 are 40:1 and my stihl chainsaw and weedeater is 50:1. I don't know, I just run my premixes at what people have told me and I haven't had any problems with any of them
ummm correction! lol that feels weird to say.
i have been working on a leaf blower all week, and it runs on 50:1 and the engine is like a 20cc
Are there fins on the flywheel which force air through a duct over the fins of the top end?
The flywheel acts as a centrifugal fan, it draws in air and forces it over the motor, that is how those little beggars are kept cool.
So bearing in mind that the leaf blower motor is temperature controlled a 50:1 mix is fine as the components are not subjected to the uncontrolled heat ravages of a passive air cooled motor.
You can also get away with a lesser refined type of oil, that is why it is not a good idea to use weedeater, leafblower, chainsaw oil in a passive air cooled motorcycle.
Sounds logical, but it is not the amount of oil in the mix that lubricates, it is the amount of oil which comes out of suspension to be thrown around by the crankshaft.