oil ratio's for rm 125c

[Naked_Amphibian]

What oil ratio is the go for air cooled two strokes? and what oil is best, castor?

[LWC82PE]

suzuki would have recommended 20 to 1 for that bike and its what i would recommend too.

[oldyzman]

I would use motorex 2T at 30:1. I would like to hear other peoples opinions about this. I would have said TTS a while ago but ive heard something it carrying moisture (water). Some old guys swear by R30 I think this is probably OK too.
OLDYZMAN

[lukeb1961]

from the FAQ.txt (Frequently Asked Questions) of the Suzuki PE list
http://groups.yahoo.com/group/PEmotorcycles/


What oil pre-mix should I use?
==============================
See your manual!!
Out of the box, all PE's ran at 20:1 oil ratio using standard 2-stroke oils of the day.
eg. Castrol R30, Golden Spectro, Shell Super M, Bel-Ray MC-1.
Be cheap - Suzuki "CCI" 2-Stroke Injection Oil works great!
These old engines do NOT have 'modern' chrome bores, etc.
Tests on the PE250B engine on a dyno showed that 20:1 gave the most power and life.

You may wish to go leaner, but don't go crazy.
List members are finding 20:1 to 30:1 to be OK, depending on the model, their riding style, locations, etc..
Leaner (eg 40:1) NOT recommended due to loss of power, increased heat and increased wear!
Search the archives - Dale Erickson wrote a VERY comprehensive discussion on oils!

[mike1948]

It'd be helpful to get some quality information on this subject.  All I seem to see is " I use X at 100 to 1 and had no trouble ".
I have no idea if the modern oils provide better lubrication or are simply cleaner burning.  I have used several brands, but always at the bikes manufacturer's original specifications.  
Am I right, or am I wrong?
There are probably many out there who use far lower oil ratios, but then again, most of us don't push the bike to it's limits either, so can get away with less oil.

[LWC82PE]

http://ozvmx.com/community/index.php?topic=2533.0

[pmc57]

Regardless of the type of oil you use, the so called oil to fuel mix ratio has a significant effect on how the carby jetting does it's job in keeping the engine lubed and cool. It's been said many times before on this forum, but if you decrease the amount of oil in your fuel, you will richen your fuel /air ratios. Adjusting your jetting WILL be required if you deviate too far from the standard manufactures recommendations.   

[LWC82PE]

so if the thought of rejetting sounds all too hard for you, then best stick to 20 to 1 or the recommened ratio for what ever bike it is.

[Lozza]

Going from 20:1 to 50:1 or the reverse, is a net change of 5%-2%=3% more fuel, if you run a Mikuni say a 200 main @ 20:1 requires a 3% jet change 200-3%=194 so a 195 main will see you through.Simple innit.

[pmc57]

Using another persons famous words. "please explain"

[Doc]

I honestly doubt with premix that there is a perfect or ideal ratio, just a compromise. It depands on 'some' variables. 30:1 works for me but it wasn't something I read just a simple case of trial and error of a period of time.

[holeshot buddy]

i would go with 30 to 1
with modern synthetic oils
for a 125

[Lozza]

If you run  20:1 oil ratio you have 5% oil in the fuel
If you change  to 50:1 oil you will have 2% oil in the fuel.
Net change is 3% more fuel or 3% less oil.
You have a Mikuni(their jets are flow rated and incrementaly linear in size ie a 210 flows 10cc per min more than a 200 main) and use a 200 main jet going from 20:1 to 50:1 require 3% less fuel so a 195 main is required and going from 50:1 to 20:1 requires a 205 main jet.
Oil has a greater density than fuel,  burn all of it and more energy is released.This is one of the reasons a dyno was a good invention as it proves fact from fiction and someone has yet to run an engine on a dyno and prove less oil makes even the same power a more oil. Remember no one killed a 2T engine with to much oil.

[Naked_Amphibian]

just fouled a few plugs? 

[Maicojames]

Over the years, with experience ( some of it expensive LOL)-and research, the more oil is better is certainly valid. The point which it stops is when it starts to cause issues on a large bore piston port. The fact remains that more oil in the mix becomes more viscous, so IME a large bore piston port engine is already at risk when chopping the throttle-say entering a turn. For those of us less talented than experts, we have a tough time keeping a few more revs while still slowing the momentum of a large bore piston port 2T single. I had always ran 32:1 until running my 77 AW440. After using some synthetics I went back to castor ( blendzall green label in US, I think R30 is equal) at 40:1.

I have watched a few older bike owners -and noticed they run a 20:1 in small bores , 32:1 in 250s (two-fiddys?) and 40:1 to 50:1 in big bores. I am talking air cooled here only. For the water pumpers, I have ran 32:1 with either a mineral ( Kawasaki brand 2t oil) or castor and no problems.  I have seen only one oil make more dyno power over others at same ratio etc of any signifigance-and that was an increase with castor. Castor, though is a PITA, need to use it quick, keep it agitated and will still separate at lower temps-particularly with fuels having spec gravity lower than about .725-and that is almost all of the decent leaded race fuels available in the US. So, you get to add a "booster" which keeps the castor mixed.
Even then, I use up the leftover mix in the mower or weedeater . -and yes, it costs more $, but IMO less than new parts.

For any big bore non reed Maico, Husky, or modded Bultaco, Monty, or CZed this has been worth the trouble( as all of these typically run hot, having high cranking pressures, and /or inadeqaute cooling-especially the Maicos). For the rest, a mineral oil or good synthetic works fine( think of stock CZed, Monty, Bul, Kx400,
KTM 400, and most all 250s). Experiencing this, to me makes a decent case for reed conversions in classes allowed-and where not to run conservative porting and timing on the piston ports. After all, are most big bore air cooled bikes really slow?