Gas/oil ratio
- Thread starter skyzo
- Start date
Old intermediate MX racer, I want the most protection and the most horsepower. 20:1. Slow or tight trail riding, yes, you can rejet for leaner oil ratio's safely. Till the bike gets wound up tight on a fire road, it will take a toll on the motor. Safely dropping the oil ratio, loosing horsepower, GOOD LUCK! A search can bring up this very question, at least once every few months, since the beginning of time. The amount of oil loss dropping to 32 or 40 to 1 is pretty scary! 76 RM250, that bike was set for 20:1 for a good reason. And now, those cranks are no longer available. Vintage Bob
The family car, maybe. 2 stroke oil has changed in the last 30 years, I do not think so. As a matter of fact, those millions of dollars done on testing of ratios? No Plynn41, guess again, or do a search, on the great oil ratio mystery. I sure wish back in the day, I would have ran all my bikes[when I was faster} and for sure my sons bikes, at 18:1. After rejetting of course. Thats a lot of great smelling 927, not some high tech crap, that says so on the bottle, it will go 100:1! If you buy an MX bike, you ride it like you stole it, you will learn. Small bores even though the manual says 32:1, if they are fast, better rejet for 25:1, at least! A novice rider will foul some plugs, or learn to ride faster! Running boat and weed whacker ratios, have you ever tried riding them on an mx track lately? Trail riding mx bikes and fouling plugs, detune the bike, like into a TTR or something? Best bang for your buck, and the best insurance you can buy, the recommended oil ratio, at least! Vintage Bob
I've had more than one professional engine tuner (including one who worked for Superbike racer Nicky Haydn) tell me that running too much oil in 2t premix will seize an engine just like running too lean. I know it's not intuitive, but the extra oil takes away from the gasoline volume, which is what supplies the cooling charge to the cylinder walls, due to gasoline's rate of evaporation. Oil doesn't cool the cylinder--it just lubricates.
And fwiw, it's not a "guess". 2-stroke oil has improved a lot over the past 35 years. I personally have been running Klotz Techniplate at 40:1 in my kid's 85cc screamer, and my 250 mx bike with no problems. The oil is a blend of synthetic and bean oil. No way did they have that stuff in 1976.
I trust the pros.
Regards, Lynn
And fwiw, it's not a "guess". 2-stroke oil has improved a lot over the past 35 years. I personally have been running Klotz Techniplate at 40:1 in my kid's 85cc screamer, and my 250 mx bike with no problems. The oil is a blend of synthetic and bean oil. No way did they have that stuff in 1976.
I trust the pros.
Regards, Lynn
plynn41 said:
If you are tuned to the ragged edge running 50:1 at Road America on a TZ250 and dumped a 20:1 mix in the engine without a jetting adjustment you might (let me repeat that MIGHT ) be able to lean it enough to cause some detonation and hurt the engine.
On the average dirt bike there is no way in hell you'll ever manage it. Nice try though. ;)
I've spent more time than most playing with jetting and oil ratios in two-strokes and I'm convinced most will never notice the fuel difference between 20:1 and 50:1 , but the engine especially the roller bearings will more than likely notice the oil difference.
Whatever your personal thoughts are on oil ratios Bob probably brought up the most rational thought. Running more oil should make a hard to replace crank last longer. Good reason to tip the oil bottle a bit more.
I defer. Bob is probably making the better point regarding a vintage bike :worship:
I don't plan to change however. I prefer not to be seen as the blue cloud of smoke circling the track.
BTW, the tuner I referenced was indeed answering a question I asked him about breaking in a new top end with double mixed (i.e., extra oil) premix (like we used to do in 1976 when I was racing snowmobiles). He told me "don't do it! It's not necessary, and I've seen engines seized that way". You're probably right that his context involved highly strung engines--I hadn't thought of that until you mentioned it.
Good discussion!
Lynn
I don't plan to change however. I prefer not to be seen as the blue cloud of smoke circling the track.
BTW, the tuner I referenced was indeed answering a question I asked him about breaking in a new top end with double mixed (i.e., extra oil) premix (like we used to do in 1976 when I was racing snowmobiles). He told me "don't do it! It's not necessary, and I've seen engines seized that way". You're probably right that his context involved highly strung engines--I hadn't thought of that until you mentioned it.
Good discussion!
Lynn
Pay me enough money, a pro, and I will sell you a bridge in Jersey? You blew it, the superbike racer, huh? You said, he said? What exactly does this mean? Did you write it down, are you sure you do not have it backwards? Not enough gas for cooling, on an MX bike, recycled cow manure! Now a 2 stroke road race engine, that may. be true. I do not care, I do not work on them, and that is another site entirely. My bikes at 20:1 smokes when cold, or waiting for a train to pass. Almost none during normal operation. The 83 or the 97. Klotz, no wonder. I blew a lot of engines up with that crap, back in the late 70's. Sorry about the 2 stroke oil is oil remark. There are and always has been snake oil for sale, in 1 form or another. Who remembers the gold label blendsall, with nitro methane no less! Piston cooling is very important for 2 stroke mx bikes. Most pump fuels cover this, race fuels you better know what you are buying! IT HAS NOTHING TO DO WITH THE OIL RATIO. Fix, jet, or learn to ride it for what it was made for. Fact, or hearsay. Now you are going to make me dig up, the OLDDDDD thread again, a whole 4 months has gone by? http://www.dirtrider.net/forums3/showthread.php?t=175076
No internet education, probably? I never took office or typing classes? I am testing out my new to me mac. I like it! It will take some getting used to, not the first, and not the last thing I will learn, or die trying. With out facts, there is chaos! Kind of like trying to find a 76 rm crank, new or rebuilt. THAT is sad. Not even Chinese knock offs, yet? The oil ratio discussion, WILL happen again, in about 4 months. Vintage Bob
Eric Kropp
Member
- Mar 14, 2010
- 38
- 0
One thing that is not being discussed here is why and engine would sieze running more oil. Some folks may not know that the thicker the mixture the larger the jetting needs to be. Thicker mixture requires needs bigger holes. Combining the the fact that it leans the bike out with thick mixtures and the fact that oil does not cool the cylinder walls adds up to seizure. I think more people foul plugs and lock up motors due to fuel and air mixture more so than oil and gas mixture. I also believe "properly jetted thick mixtures will keep the bearings and walls alive longer. Nothing like Castrol R or Blenzall at 20:1 mmmmmmmmmmmmmmmmmmmmmmm
Eric
Eric
Got any proof of this engine seizing due to too much oil? When jetting to more oil, you are naturally going to be going bigger, bigger jets. Its kind of obvious how that got turned around. And you have to remember, a lot of MX bikes came already set to run 20:1. Along comes a misdirected soul with spooge problems and what not. He drops the oil ratio, and thereby is dumping a lot more fuel in. But the rich gas does not foul plugs as easy as the oil does? Its easier to keep the plug hot? Nothing but going the wrong way. Regardless of how many swear by it. Its more they are telling on themselves that they can't, jet, properly maintain it/cheap, or ride it correctly. Take your pick. I did not make it that way. That is just the way it is. So when somebody brings up the old wives tales guess what, that is offensive. Every 4 months. Eric, you are early. Vintage Bob
- Aug 29, 2004
- 2,958
- 0
there was once a man in 1937 who neglected the transmission in his ford austin, so after 70,000 miles he decided to change the trans fluid. needless to say the next day his trans took a hot steamy deuce. to this day if you have neglected your trans for too long you better just leave it alone or every half-arse mechanic WILL warn you your going to be needing a trans TOMORROW
I heard the same story about a 95 ford truck tranny! Vintage Bobellandoh said:
- Aug 29, 2004
- 2,958
- 0
whenfoxforks-ruled said:
i got a 92 f150 bought it with 230000 on it and purposely tested this theory................myth busted. i got 90000 more on it SO FAR.
my point was, it only takes one coincidence to create an urban legend.
if some fella trashed an mx bike from running too much oil, ill eat my hat if there wasnt a secondary "coincidence" to the story?
Eric Kropp
Member
- Mar 14, 2010
- 38
- 0
whenfoxforks-ruled said:
Vintage Bob, you and I are on the same side of this discussion I think. Seems like you validate what I wrote and I agree with what you say. More oil bigger jets. More oil, longer life. Bean oil, better smell :cool:
Eric
You got it. 927 and premium, or Xamax and Fire Power. 20:1 means almost the most horsepower, jetted, you know when it hits in the powerband! Slipping or fanning the clutch, a dearth wish. As quick as you can snap the throttle on the stand, it does it in the dirt. There is 1 way they work best, follow the manual. And when parts no longer are made new, you sure wished others would have bothered. The bikes are a lot more fun running correctly, and SAFER! Ride fast, and die hard. Vintage Bob
2strokerfun
Member
- May 19, 2006
- 1,500
- 1
ellandoh said:
I've always heard the same thing. And I heard an "expert" transmission mechanic on radio program the other day say there is some truth to it because atf has about 14 times the detergent motor oil does and once you let one go 90,000 or so without a change, the new fluid will loosen up all the gunk and put it through your tranny.
Don't know about that, but I strongly suspect that most times somebody tries to change fluid for the first time after 90,000 or more without ever changing it before, that they are doing it to try and fix a problem. And once those overly worn plates or bearing is there, the too-late fluid change will not magically repair the problem. Been there. And yes, trying to spend $35 in atf is cheaper than $2,000 for a rebuilt transmission, but where there is obviously a serious problem, it is still throwing $35 away.
Eric Kropp
Member
- Mar 14, 2010
- 38
- 0
I teach a lot of youth groups and young welders and use analogies a lot. I presume the transmission comment/description is an analogy....but I can't make the connection. Can you enlighten me?
Eric<><
Eric<><