Vintage 2 stroke oil injection systems, why the hate?

Posted at 1/9/2014 11:59:57 AM

thejunkman

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Vintage 2 stroke oil injection systems, why the hate?

I had gotten to thinking about this one day. Why do most people deem these so unreliable? Almost everyone's knee jerk reaction to the question; to keep or not to keep the oil injection on my vintage motorcycle. Well here are my thoughts, take them or leave them.

Why everyone wants to disable 2 stroke oil injection pumps

Posted at 1/10/2014 9:27:49 AM

Richard47

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I own two two-strokes with oil injection pumps, and have owned several more in recent years. I would never disable them. I have only ever had problems with one when the pin on a Yamaha pump came out and the pump wouldn't deliver at more than tickover rate. That did make it sieze, but not terminally and I did manage to limp home.

If anyone does decide to use premix there can be problems with certain brands. Yamaha's are easy enough to do as the oil is injected into the inlet tract, so it gets around the engine in the same way. With the Suzuki's I have owned at least one main bearing is lubricated direct from the pump, with the oil finding its way to the rest of the engine via a 'flinger' plate on the crank. This, presumably, would have to be removed or oil would not be able to get to the bearing. I can't speak of Honda's, Kawasaki's or Bridgestone's, as I have never had the pleasure of dismantling them.

You are right about the oil on the rider's back. Not too long ago, when I had a high-pipe T250, I bought a new jacket. Unfortunately it was a silver color, but not when I returned from the ride! Even on my TC90 I would come home smelling of burnt two-stroke. You are right too, when you mention the poor quality of oils 40 or 50 years ago. Decokeing the muffler of my Suzuki 80 was an all too regular event.

Old git on an old bike.

Posted at 1/10/2014 7:05:03 PM

Hexford

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The thought to disable the oil injection on my H-2 never came up as a good option. In fact it seems dumb.

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Posted at 1/13/2014 10:33:43 AM

Bakemono

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Its just an old wives tale. Someone told his buddy that his engine siezed because the oil pump failed and he told his buddy, who told his buddy and next thing you know, people think oil injection is unreliable.
I rode snowmobiles for almost 30 years, riding at least 3,000 miles a year and never did I have a problem with an oil injecton system failing.

Posted at 1/20/2014 7:24:33 AM

thejunkman

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Bakemono said:Its just an old wives tale. Someone told his buddy that his engine siezed because the oil pump failed and he told his buddy, who told his buddy and next thing you know, people think oil injection is unreliable.
I rode snowmobiles for almost 30 years, riding at least 3,000 miles a year and never did I have a problem with an oil injecton system failing.


This is probably pretty accurate, and I state that in my article.

Posted at 1/20/2014 1:06:56 PM

kz1000st

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I had oil injection on my 1974 H-1 and there's something else. The oil was injected into the main bearings first before spilling out into the crank to aid bearing life. Also the pump was connected to the throttle by cable and the cable moved a cam shaped controller that allowed more oil to be injected at higher throttle openings. It worked just fine. I sold the H-1 with 30,000 miles and it still ran like a banshee. I forget what injector specific oil I ran but it worked just great with little smoke or carbon buildup.

Posted at 1/27/2014 1:09:06 PM

stexch

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I was once told that "pump" is a misnomer, since it is a simple gravity drip system. Is that correct?

Posted at 1/27/2014 11:25:02 PM

Bakemono

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stexch said:I was once told that "pump" is a misnomer, since it is a simple gravity drip system. Is that correct?

Thats a new one to me. :saywut: I dont know about bikes but I know that snowmobiles have an actual oil pump.

Posted at 1/28/2014 1:42:54 AM

Richard47

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It's not correct. The pumps get the oil fed to them by gravity, then they pump the oil to where it enters the motor. In the case of my RD250 that point is the carbs. On my TS90 the oil is fed to near the main bearings. The Suzuki system is more sophisticated but I wouldn't say that it does a better job.

Of course, the pumps don't pump a great deal of oil, the idea being to only pump sufficent oil for the needs of the motor at the time and so reduce oil consumption and plug fouling. But they do pump the oil under a little pressure.

Old git on an old bike.

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