Best fuel/mixture ratio

[benji.dojo.3]

Hi guys,


Just wondering what the best fuel/mixture ratio is.

Currently running at 32:1 , some guys suggest running it at 40:1, Using MOTUL Oil also.

All suggestions would be much appreciated.

Thanks

[cnrcpla]

Depending on the oil, 32:1 is usually a good mix. I run it with valvoline two stoke mix and it works well for me. Depending on the jetting and the carb some people can get away with running up to 50:1 or even leaner using synthetic oil or some magic stuff  But 32:1 is usually pretty safe and good to run.

[benji.dojo.3]

Yeah I got bigger jets, when I put the fmf fatty pipe and powercore 2 silencer, rejetted.

running 32:1 at the moment bike runs a dream, just a thin bit of smoke behind the bike thats barley visible to the eye, but heard 40:1 gets more power but more chance of blowing the motor up?

[Jeram]

Yeah I got bigger jets, when I put the fmf fatty pipe and powercore 2 silencer, rejetted.

running 32:1 at the moment bike runs a dream, just a thin bit of smoke behind the bike thats barley visible to the eye, but heard 40:1 gets more power but more chance of blowing the motor up?

less premix will absolutely positively NOT make more power, who ever told you that is full of shit 

The opposite has been proven, more oil on the bore and rings = a better ring seal = more hp
I run 20:1 but it gets expensive, stick to 32:1 if your motor is stock-ish

[benji.dojo.3]

Yeah I got bigger jets, when I put the fmf fatty pipe and powercore 2 silencer, rejetted.

running 32:1 at the moment bike runs a dream, just a thin bit of smoke behind the bike thats barley visible to the eye, but heard 40:1 gets more power but more chance of blowing the motor up?

less premix will absolutely positively NOT make more power, who ever told you that is full of shit 

The opposite has been proven, more oil on the bore and rings = a better ring seal = more hp
I run 20:1 but it gets expensive, stick to 32:1 if your motor is stock-ish

All i have done is change the pipe to a FMF fatty , powercore 2 silencer, put bigger jets & put the mototassinari vforce3 in.

[beaner]

The opposite has been proven, more oil on the bore and rings = a better ring seal = more hp
I run 20:1 but it gets expensive, stick to 32:1 if your motor is stock-ish

I understand the theory, but I have yet to see any relevant proof of this. Everybody seems to refer to tests that were done almost 40 years ago when materials and oil were a lot different than they are today. Do you have any info?

That aside, it's impossible to make a recommendation without any information, like bike, riding style and application.

[arnego2]

less premix will absolutely positively NOT make more power, who ever told you that is full of shit 
The opposite has been proven, more oil on the bore and rings = a better ring seal = more hp
I run 20:1 but it gets expensive, stick to 32:1 if your motor is stock-ish

+1 I run it 25:1 as I have to slow down once in a while and 20:1 at low rpm is not really the best.

[citabjockey]

The prior owner of my KTM380 was running BelRay MC1 (full synthetic) at 50:1 -- which is what BelRay says to run it at. When doing this there was plenty of smoke and seemed to work ok but there was also some significant spooge. That stuff is like pancake syrup coming out of the bottle -- very thick. Takes some significant shaking to get it to mix with gas. I would guess that the sheer thickness of the stuff is maintained even when mixed with gas is preserved which is how you can get away with the low ratio.

That is the ONLY full synthetic I have used and since have stopped (because its tough to measure accurately, makes a mess when working with it, and is bloody expensive and is a 30+ year old oil design). I lately have been using the Lucas semi-synthetic at 32:1. Before that I had history with several mineral based 2T oils at 32:1 and never had any problems.  The Lucas stuff seems to maintain that tradition. It mixes easy, very little smoke or spooge, no fouling plugs and the engine seems quite happy with it. And its pretty cheap and easily available at lots of auto parts stores around here.

[Jeram]

The opposite has been proven, more oil on the bore and rings = a better ring seal = more hp
I run 20:1 but it gets expensive, stick to 32:1 if your motor is stock-ish

I understand the theory, but I have yet to see any relevant proof of this. Everybody seems to refer to tests that were done almost 40 years ago when materials and oil were a lot different than they are today. Do you have any info?

That aside, it's impossible to make a recommendation without any information, like bike, riding style and application.

bernouli's principals is not effected by time, they are much older than 40 years. and just like newtons laws of motion they are constant and will never change.
you put some viscous fluid between the piston, rings and bore therefore constricting this 'orifice' by some degree which reduces the total volume flow possible for a given pressure differential.
As a consequence a slightly higher pressure in the combustion chamber is observed.

Makes perfect sense to me.
but by far the biggest gain is superior engine protection.

[beaner]

So you have nothing then.

I'm wondering why manufacturers like Rotax and KTM (not to mention the trials guys at 80-1 and 100-1) are recommending 50-1 and 60-1 now. I suspect that with modern materials and modern oils, that 32-1 is overkill for anything but riders at the top level, or 2 strokes that are truly run on the ragged edge. Something that most of us will never do.

[arnego2]

It really depends on you riding style. And how much you use the bike. Frequent riders which ride hard use 32:1 or even 20:1 as the ring seal will be better. Weekend rider with small trails use do 50:1 or even 100:1

[benji.dojo.3]

The opposite has been proven, more oil on the bore and rings = a better ring seal = more hp
I run 20:1 but it gets expensive, stick to 32:1 if your motor is stock-ish

I understand the theory, but I have yet to see any relevant proof of this. Everybody seems to refer to tests that were done almost 40 years ago when materials and oil were a lot different than they are today. Do you have any info?

That aside, it's impossible to make a recommendation without any information, like bike, riding style and application.

I have no info just was what some guys were saying down the track, and I myself run 32:1 or sometimes 31:1 And the bike runs like a dream plenty of power, and goes like crazy. Was just wondering what other guys were running thats all. And I don't ride trails very much, bike spends all its time out on the track.

[Stusmoke]

Castol fully synthetic @ 32:1 for me. Always worked well but has a hell of a lot of spooge. My 250 loves the stuff thats for sure.

[cnrcpla]

While we are on the subject of different power output for mixes, I heard around the track and places the expression "leaner is meaner", why do they say that if leaning out the mix doesn't crank out more power?  I don't personally believe it is true, I run a bit rich anyways, but I'm just wondering...

[2STROKEREVOLUTION]

It really depends on how you ride. If you are MX racing hard with non-synthetic, go with a mixture in the 40:1 range. I ride trails, sometimes hard, and run full-synthetic Motorex and use 50:1. The manual says I can run up to 60:1 for trail riding. With modern Synthetics 32:1 is old news.

For the mixture vs power debate. I would think since less oil = more gas, and more gas = more power, then less oil = more power. This may just be made up for in the required re-jetting though.