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Synthetic 2-stroke
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Posted by: Indy
I was wondering if anyone tried synthetic 2-stroke - a buddy of mine riding a 86 cr500 is mixing his fuel at 50:1 with synthetic oil. I am using honda 2-stroke at 32:1. Is their any advantage to mixing gas at 50:1. I am worried about wrecking my motor - any thoughts?
Posted by: Jaybird
I doubt this is in the 'high technology' relm, but what type of bike are you riding? Wait, it doesn't matter, you would be going the wrong way.
Fact: You must have the bike jetted for whatever fuel mixture you use.(also taking into account the RH, BP, Amb.Temp.,Elev., riding style)
Fact: More oil means an increase in compression, AND protection, which equates to more HP and longevity of your parts.
Fact: MFG's recommend oil/fuel ratios for reasons other than providing you with the optimum mixture information.
Posted by: Chief
Jaybird,
What are the reasons the manufacturers recommend specific ratios? Please explain. Since My bike has a sticker on it recommending 32:1, and a richer mixture (such as 32:1) is desireable, why would I want to go leaner or richer on a 250?
Thanks.
Joe Chief
Posted by: spanky250
Quote:
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What are the reasons the manufacturers recommend specific ratios?
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Pressure from environmental groups and the EPA are first and foremost in their recommended ratios. It's a proven fact that two-strokes make their best power at around 18:1 mix ratios, and higher oil concentrations translate to extended life for cranks and rings. Here's a reply that I wrote on this subject a while ago that I saved to keep from re-typing it all again (I know, I'm lazy :confused: ):
OK, looks like it's time for a little pre-mix 101. I don't usually get into ratio discussions, because mix ratios are like religions to most people, and they tend to be closed-minded on the subject, but I'll put in my $.02 here anyway.
There is a prevailing myth that less oil is better, and that the oil in the fuel is what lubricates the engine. Both are wrong. The engine is lubricated by the residual oil that builds up in the crankcase. All the oil in the fuel does is replenish this oil.
The best way to determine if you are running enough oil is to check the level of the residual oil in the crankcase. If the ratio you run leaves enough residual oil in the crankcase to cover about 1/8" of the bottom of the crank wheels, then you are fine. If you don't have that much residual oil in your crankcase when you pull the top-end off, you aren't running enough oil for your riding style and conditions.
With that said, to have that amount of residual oil in the crankcase at 50:1 (a ratio made popular by magazines and oil bottles), you can't be riding very hard, or your bike is jetted richer than necessary simply to deliver enough oil. I arrived at 26:1 for my bike with my riding style because that is the amount that gives me the proper amount of residual build-up. Small-bore engines require greater oil concentrations than larger engines to achieve the proper amount of residual build-up, because they rev higher and have higher intake velocities. Along the same lines, someone that pushes the engine harder, and keeps the revs higher, also needs to use higher oil concentrations to achieve the proper residual build-up.
To understand why the residual oil is so important, you have to understand what happens to the oil in your fuel when it goes into the engine. While the oil is still suspended in the liquid gasoline, it can not lubricate anything. It has about as much lubricity at that point as straight gasoline. When the gasoline enters the engine, it evaporates, dropping the oil out of suspension. Now that the oil is free, it can lubricate the engine, but it must get to the parts to lubricate them. The way it gets to the bearings and onto the cylinder is by being thrown around by the spinning crankshaft. Some of the oil eventually makes it into the combustion chamber, where it is either burned, or passes out the exhaust. If the combustion chamber temps are too low, such as in an engine that is jetted too rich, the oil doesn't burn completely. Instead, some of it hardens into deposits in the combustion chamber, on the piston, and on the power valve assembly. The rest becomes the dreaded "spooge". The key to all of this working in harmony is to jet the bike lean enough to achieve a high enough combustion chamber temperature to burn the oil, but also still be able to supply enough oil to protect the engine. If you use enough oil, you can jet the bike at it's optimum without starving the engine of oil, and have excellent power, with minimal deposits and spooge. At 50:1, you simply can't jet very lean without risking a seized engine due to oil starvation.
With the high oil concentrations that I use, I tend to get far more life from my cranks and rings than most of my friends that run leaner oil ratios. The high oil content also produces better ring sealing, so more of the combustion pressure is retained.
People argue about the higher oil concentrations, saying that it will create a lot of spooge. Not so. When jetted properly, you can run high oil concentrations, and get virtually zero spooge. I can stick my finger in my tail pipe and have no oilly residue in my silencer.
The basic gist of all of this is to make the point that there isn't one single ratio that is right for every rider and every bike. You have to find the correct ratio for you by trial and error.
One small point. No one ever broke an engine by using too much oil. (That quote is from Rich, and it’s so true)
Posted by: Jaybird
LOL, yeah...what spanky said! 
Also, Chief....When you look at the bottles of some(most) oils, they recommend a mixture ratio. Knowing what you know now, do you see any way they can make that recommendation? They have no idea what bike you are riding, your riding style, or anything at all that is pertinant, for that matter.
Those stickers are boiler plate statements, at best.
Posted by: Chief
Spanky and Jaybird, Thanks for the replies. It's always great to learn something new. Especially about the 2 stroke.
The part about the the oil being suspended and then dropping off was particularly enlightening.
I use 32:1 for 2 reasons, the sticker (ok, I know better now) and other posts I have read seem to point out that for a 250, 32:1 is a good, conservative middle of the road ratio. Also, the oil bottles are marked in 2 oz intervals (talk about lazy).
Since the temps here at appx 1000 ft above sea level aproach 90 at this time of year, I have made several attempts at leaning out the airscrew and bypass knob (closed to 3/8 throttle) which is where I'm at most of the time. I always go back to what I am set at (1/2 turn out and 4 clicks out on the bypass knob) because the bike has a tendency to surge or ping otherwise.
Maybe I should be looking at dropping the needle to the lowest setting instead, but I'm paranoid since the last time I did that I seized it. I've had the head done over for pump gas and tight woods riding, but the thought of seizing it again overrides everything else.
I have a pretty good feel for the main since I do some climbing wide open.
I really got off topic here, sorry. I guess I might try a richer ratio, say 5 oz to a gallon which is 25.6:1. Then re-jet (I've changed many a jet since I got the bike last august.) what do you think??? suggestions please.
Also, with the higher temps and need for leaner jetting, the spooge is making a slow comeback. If the lower throttle adjustments aren't working, yet I'm still getting some spooge, maybe I'm missing the mark and should be looking at the needle. Man, now I'm really rambling.......
Jaybird, I find the Golden spectro label particularly enlightening, 50:1 for technical riding....... I like the oils that make no recommendations. They are less confusing.
Regards and Thanks.
Joe Chief
Posted by: KDX220rm
I always used Yamalube 2R with was a semi-synthetic until I was turned to Mobil-1 MX2T which is a full synthetic and couldn't believe the improvements. I still mixed it 40:1 like I did the Yamalube.
Posted by: Chief
KDX220rm,
The mx2t is the oil I use. It's priced reasonably, and it really does improve overall perfomance. Total cost is about 3.50/pint, order on the web, shipped to my door. Not much to complain about. I guess I'm going to try more oil, I just need time to mess with the jetting when I find the time. I also liked the Amsoil. It peformed similarly, although I never checked into bulk quantities, it is nice to have a red premix instead of clear.
Joe Chief
Posted by: Jaybird
The color thing is something I don't like either, Chief. However, I get around it becasue I have a working relationship with Mobil and get dye given to me whenever I want it. Whenever I mix up more than 2 gallons, I put in some red dye....which makes my crappy turbo blue/mx2T mix look a nice purple.
btw...mobil does offer dye to the public.
You mentioned Spectro Golden....I used to use it and it performs well, but is one messy oil when it comes to spooge and power valve/exhaust train coating. And at $9 a pop....no thanks.
Posted by: Chief
Yea Jaybird,
I had the same experience with the spectro. It spooged a lot, but in addition it ran crappy in my bike. I just gave away (3) 12 oz bottles from my experimental days. I said "Man, I really hate to do this to a friend", but to each his own I guess. I can't believe how many riders I know around here that use the spectro. I guess it works for them though. different brand bikes.
On a similar note, I showed my buddy my freshly lubed chain and he almost didn't believe me that it was just lubed. Then He pulled out a can of his 'tar' and pointed it at my chain. I practically begged him not to hit the button because if he did I knew I was gonna get really pissed. Luckily he didn't.
I'm kinda regretting I bought the r1 works chain for my replacement since the d.i.d. o-ring is working so well. The $ is spent and it will be my replacement. It might give me some more experience on o-ring vs non-oring though.
Chief
Posted by: KDX220rm
Hey Cheif,
I purchased some red oil dye from a petro company that I am mixing with my MX2T. If you would like some, it cost me $2.00 an oz and the shipping is $.50 and the package is $.50 for a total of $3.00. I am making no money, but just glad to help people that don't like the clear color. It only takes 8 drops per pint bottle and will last forever. I go ahead and open the MX2T and put 8 drops into each bottle so all I have to do is measure it out and pour it in my cash. If you are interested in some dye, just email at RICKM7331@aol.com
Posted by: KDX220rm
Chief,
Sharp looking RM250. Glad to see someone appreciates keeping their bike nice like my KTM. 
Posted by: old#48
If you really want more punishment, take a look at the thread "Bel-ray Mc1" right here in this same forum for more pre-mix info and yes, click-on links to even more dirtrider.net oil threads - o'boy, o'boy, o'boy.
Contain yourself now, don't want you lookin' like your dog when he's eatin' a treat of that $0.33 a pack Ol' Roy's Gormet Dog Food from Walmart.
Now that was just a joke, don't anyone take that personal, OK ?
Posted by: DEA
When in doubt KLOTZ it "less filling & smell's great
Posted by: old#48
Dang, the more you guys keep talking about Klotz's smell, I might just have to try the damn stuff - if for nuthin' else but to see the reaction of the guy's I ride with.
Now that I think about it, my dad used Klotz back in the early 70's in my Mac engined Dart cart - and I thought that thing kicked ass - even with it's old chrome motorcycle pipe across the back to quiet it down.
Posted by: Chief
KDX220rm,
Thank You on both posts. I'll drop you a line shortly.
Sincerely,
Joe Chief
Posted by: KDX220rm
I hear if you really want to gum up your powervalve, then Klotz it.
Posted by: bwalker
or rust you crank.
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