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  • What to do with 2 stroke oil pump?

    Hi. I recently just got a free 2 stroke 80cc dirt bike, Well, free on the condition I fix it and the one just like it my brother has

    One thing I noticed was he disconnected the oil pump and uses premix gas instead. I have read this is a good idea (as the pumps can't be trusted, failure means total engine death and they are not reliable, also running outta oil = engine death) but I noticed dirt getting in the disconnected pump intake line.

    So I am wondering if I should just plug the intake line? Shouldn't damage anything right? I am also going to disconnect the throttle cable to it as the throttle cable line is too stiff and I think I am just going to move to a single line that goes to the carb directly. (current throttle won't spring back!)

    Or should I just connect it to the empty oil tank? I am a little concerned about it sucking air through the oil pump at idle and messing up the mixture at idle.
    Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.

  • #2
    I rode Yamaha enduro model bikes for many years. They all had the Autolube feature, tank, pump and plumbing. I pounded on these bikes for years and never had an oil pump failure. Let's face it the pumps run in oil. The only time there was a failure is when the operating cables weren't maintained and they frayed or broke. From what I'm reading that's exactly what has happened to this machine. Changing to premix is an option but also a pain in the butt. If you do go the mix route just take the cable to the pump off, there's a splitter in the line, one to the carb and one to the pump, then just disconnect the oil lines, one from the tank and the one at the nipple on the intake manifold. You'll have to plug the one at the manifold with a vacuum cap.
    gbritnell

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    • #3
      I'd remove the pump completely and make a small block off plate for the hole left behind. Remove and cap off the lines going to the carb from the oil pump.


      This is also a common deal to do with outboards (OMC) that had the VRO oil system that would also randomly fail or not pump enough oil and kill the engines.
      Andy

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      • #4
        +1 gbritnell

        I would repair the pump. Many of these pumps were a variable delivery rate. Increased plug life and reduced fouling. Used to woirk on Bridgestone motorcycles and never had a problem with them either.... of course they went away when the EPA cracked down on the oil smoke. I think it was a conspiracy by the 4 stroke engine cabal.

        paul
        paul
        ARS W9PCS

        Esto Vigilans

        Remember, just because you can doesn't mean you should...
        but you may have to

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        • #5
          run engine on pre-mix but run oil to pump - put output line of pump into small catch container, unhook pump cable,,,

          measure after half hour of run time, this will give you "idle" output for pump as if it ran for a half hour idling,

          then - jam pump on full throttle position and run bike around for a half hour - does not matter how you run it...

          then measure pumps output, equate both measurements to the amount of fuel bike would use in both situation's (take a wild guess) if the ratio is close then connect pump back up to bike and fill it's reservoir and run straight gas and keep a close eye on "smoke"

          you don't have a cat. on the bike so should be easy to tell...

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          • #6
            Hi
            "I have read this is a good idea (as the pumps can't be trusted, failure means total engine death and they are not reliable",
            Do not believe all you read so you can totally ignore this!
            There are Millions of two stroke engines world wide that run reliably with the oil pump supplying oil to the motor.
            Fix or replace the original pump and set it up properly and with the oil tank kept full reliable for fuss free running.
            Throttle-Oil Pump cables need to be in good condition, properly lubricate and adjusted to get best performance.
            Being an old timer before the advent of specialist two stroke mixes it was PITA mixing fuel and oil.
            There was the odd motor cycle that ran a pumped lube oil system in the 1920s.
            Eric

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            • #7
              Modern(ish) 2-stroke bikes have oil pumps to.make.them reliable! In the.premix days engines.seizing.was pretty common, usually on a closed throttle down hill - closed throttle = no oil along with no petrol...
              Fix and.adjust the.pump!
              Rules are for the obedience of fools, and the guidance of wise men.

              Holbrook Model C Number 13 lathe, Testa 2U universal mill, bikes and tools

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              • #8
                Also, some oil pumps also supplied the oil directly thorough the bearings to provide adequate oiling of said bearing. The old Kawasaki sled engines (with oil pumps) used to be like this. People unhook the very dependable oil system and end up eventually with toasted center bearings.

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                • #9
                  This one injects the oil into the intake. I put a vacuum cap over it. I have had good luck with premix, especially at 30:1. No fouling if you use a good oil and have your carb set right.

                  I don't even know if the oil pump is broken, it just came disconnected. Personally Id rather just stick to premix.

                  We do have lots of hills around here, but none of them go downhill for very long and they are way too steep to use engine brake.

                  AK boomer: I believe the pumps output would also vary with RPM.
                  Velocette: Of course there are millions of 2 strokes with working oil pumps. The ones with non working oil pumps are usually scrap by time the owner finds out his oil pump is not working.

                  Incidentally I took a look in the combustion chamber, very clean, almost no deposits. Although maybe that is because it has not run much since the owner last did maintenance and put in the wrong spark plug.

                  Hmm, I may of just realized the biggest reason for removing the oil pump and using premix.

                  Its fool proof. Well ok you can put non mixed gas in and ruin the engine, but as long as you grab the right gas can (I use 1gallon cans only for premix, 2.5 gallon cans for pure gas), if you ever run out the engine just stops till you add more gas. If you run outta oil with an oil pump, the engine just stops... And never turns over again.

                  One less tank to check.
                  Last edited by Black_Moons; 08-05-2014, 01:42 AM.
                  Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.

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                  • #10
                    I am a big fan of premix, for the reasons Black Moons stated. Its not so good for commuter bikes as the high ratio of oil is likely to cause fouling at low engine speeds, because my bike runs in the 7500 to 10,500 range this is not a problem. If I mix up 20 litters of fuel (5 US Gallons) I use 640ml (1 pint) of oil, a pump would half that. When you convert to a premix you need to jet a bit richer as 3% of the fuel mixture isn't fuel , or the engine will run lean
                    My neighbours diary says I have boundary issues

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                    • #11
                      The pump output varies with rpm, yes, but so.does the need for oil - look at it the.other way, the.pump delivers the same amount of oil per revolution of the engine at a constant throttle, and.the link to the.throttle cable increases it under load, just what you want. With premix you need enough oil for all conditions at all times, so it over-oils and.fouls plugs at light loads!
                      I like pumped oil, my old Suzuki triple.had it and I never managed to seize it, not.even once, my premix-lubed Bultaco was.always seizing....
                      Rules are for the obedience of fools, and the guidance of wise men.

                      Holbrook Model C Number 13 lathe, Testa 2U universal mill, bikes and tools

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                      • #12
                        Originally posted by Black_Moons View Post
                        AK boomer: I believe the pumps output would also vary with RPM.
                        Velocette: Of course there are millions of 2 strokes with working oil pumps. The ones with non working oil pumps are usually scrap by time the owner finds out his oil pump is not working.

                        That's a good point and it will vary things, still should be a huge difference between the pump locked on full as compared to Idle, no matter the RPM's - Now it makes me wonder, does "lugging" one of these engines load it up with extra oil?

                        what about coasting in gear down a huge grade? throttle all the way backed off (and pump) yet RPM's up high...

                        I don't think with just a few things controlling the oil injection that it's an exact science, but I would not go with the "smokeless" oil if using a pump and trying to dial it in - would be using the smoke as a gauge...

                        In all my years as a motorcycle mechanic iv never had one of those pumps apart,,, im curious now what they use for a pump and how they meter it...



                        I also would think that with all the emphasis on emissions and such and many engines already running off of computer controlling that it would be an area to further refine and clean up the two stroke as far as the oil part,
                        would actually surprise me if they don't already have computer controlled oil injection that not only uses TPS and RPM's for the pump but also has it hooked to load sensors or even just run it in parallel with the fuel injection rates...

                        There has to be some crazy plans on the drawing board right now for two strokes and direct injection gas, this could help clean up the other part of these engines and drastically increase their efficiency in the process,,, no more raw fuel going directly out the exhaust port,,, they could concentrate little amounts of oil in hard working area's without it getting diluted, and just inject pure fuel, doing anything else would be a total waste of oil and create extra emissions.

                        In fact two strokes stand to benefit from direct injection gas more so than typical four strokes... it would cure many inherent problemo's

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                        • #13
                          I like 2 strokes allot more than 4 strokes. It just makes more sense to me to power every stroke of the piston instead of every other stroke. No oil changes, motor can run upside down, sideways, what have you. 2 strokes are smaller lighter and put out more power and they smell great!
                          Andy

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                          • #14
                            I don't like the inefficiency, the lack of longevity - I also don't like the oil burning,,, four strokes have also come a long way as far as power production, they may only make half the mount of power strokes per revolutions but there power stroke is almost twice as potent and way over twice as potent if you toss on a supercharger or turbo,,,

                            not something you can do easily on a two stroke, (unless it's a detroit diesel ((direct injection))

                            but the entire rule book is changing right now,,, direct injection gas is changing the way both these engines run and the two stroke is going to make a huge comeback due to it benefiting it on so many levels... they will be far cleaner, they will last much longer, and they will have much better efficiency,,, but there is still one inherent problem left --- they cannot achieve as optimum of a crank/rod angle for torque production as much of their piston travel at the lower half of the bore is dedicated to both intake and exhaust porting,,,

                            but, toss in a valve at the top of the chamber - an intake --- now you can run just an exhaust port way at the bottom of the stroke and either turbo or super the intake, now you got something,,, immense power with increased efficiency...

                            they are going to be tough to beat... mark my words they are about to make a crazy comeback and we will even be seeing them in cars (again).

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                            • #15
                              Originally posted by Mister ED View Post
                              Also, some oil pumps also supplied the oil directly thorough the bearings to provide adequate oiling of said bearing. The old Kawasaki sled engines (with oil pumps) used to be like this. People unhook the very dependable oil system and end up eventually with toasted center bearings.
                              Along those same lines of thought, my 1976ish Suzuki 500cc twin injected the oil into the crank bearings and through the cylinder walls directly to the piston skirt. It's been a long time, but I don't think that it injected any oil into the fuel stream,

                              paul
                              paul
                              ARS W9PCS

                              Esto Vigilans

                              Remember, just because you can doesn't mean you should...
                              but you may have to

                              Comment

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