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Post by tortoise2 on Aug 2, 2018 12:25:20 GMT -5
pump not being able to circulate oil and cause failure of the engine Note that the GY6 aftermarket kits install in the SUCTION inlet flow to the oil pump . . PULLING oil flow through the cooler. This configuration leaves a LOT to be desired! Original equipment 125/150 engines tap the case PRESSURE outlet flow from the oil pump. Unfamiliar with ANY 139QMB 50cc 4-stroke engines with an original equipment oil cooler. The Honda and Yamaha engineers went with liquid cooling on some of their 50cc 4-strokes . . such as the Vino and Metropolitan. |
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PirateLabs
Scoot Enthusiast
Posts: 296
Location: Bowling Green, KY
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Post by PirateLabs on Aug 2, 2018 13:04:57 GMT -5
With both option and i think especially the second, oil may get air bubbles in it and it is more likely to kill your engine Why would that be...exactly? If the systems were closed and air could not be introduced, then how would it get into the systems? What am I missing here?  Bill |
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Post by dexameth on Aug 2, 2018 14:05:42 GMT -5
I have an oil cooler and will be installing it on my 93.4cc stroker 139QMB. I've thought about bleeding the system many times, and with the banjo's facing up or down, pre-filling the radiator... etc.
My scoot is naked, and there's a good spot on the frame right behind the battery on the floor to mount it, and it'll get good airflow there. My lines will then run right back under the motor to the screen bolt adapter. I want to run my banjos on the radiator facing down for a more clean look and direct line to the adapter, but if air got in the lines it would then rise to the top of the radiator and not allow it to fill completely with oil. Will the system purge itself? I guess we'll find out...
I myself run WOT with high rpms a lot so I need the cooling... especially here in Florida. No CHT guages at all so I can't really do a before/after test, I'm just gonna go on good faith that it will help the longevity of my motor.
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Post by gouvis on Aug 2, 2018 14:52:43 GMT -5
With both option and i think especially the second, oil may get air bubbles in it and it is more likely to kill your engine Why would that be...exactly? If the systems were closed and air could not be introduced, then how would it get into the systems? What am I missing here? Bill The way this oil cooler circuit will work may not be able to to pump oil when the scooter leans for a turn. It will suck air and return it back to your oil pan next to your mechanical pump. That's why i told that i don't like this method much. I may be wrong but i wouldn't try it because i usually ride my scooter roads with turns but if you ride it most on flat straight roads it should be okay. Also i find the oil cooler a little bit unnecessary. I leave in Greece and the temperatures here are now almost 40 celsious. I do almost 50-100kmh a day and my scooter is 50mm with a naraku crankshaft. It has almost 30000km. I build this engine about 26 months ago and i run wot almost all time. I use motul 10w-40 scooter and i run a little richer. Oil changes every 1000-1500km. Now after all this abuse i will replace my piston and cylinder because i get a little oil consuption. So an oil cooler will benefit an engine like this but it will add complex and maybe issues. So i think that for a racing motor where max hp is the need yes, but for daily ride maybe yes, maybe no |
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PirateLabs
Scoot Enthusiast
Posts: 296
Location: Bowling Green, KY
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Post by PirateLabs on Aug 2, 2018 15:27:04 GMT -5
Why would that be...exactly? If the systems were closed and air could not be introduced, then how would it get into the systems? What am I missing here?  Bill The way this oil cooler circuit will work may not be able to to pump oil when the scooter leans for a turn. It will suck air and return it back to your oil pan next to your mechanical pump. That's why i told that i don't like this method much. I may be wrong but i wouldn't try it because i usually ride my scooter roads with turns but if you ride it most on flat straight roads it should be okay. Also i find the oil cooler a little bit unnecessary. I leave in Greece and the temperatures here are now almost 40 celsious. I do almost 50-100kmh a day and my scooter is 50mm with a naraku crankshaft. It has almost 30000km. I build this engine about 26 months ago and i run wot almost all time. I use motul 10w-40 scooter and i run a little richer. Oil changes every 1000-1500km. Now after all this abuse i will replace my piston and cylinder because i get a little oil consuption. So an oil cooler will benefit an engine like this but it will add complex and maybe issues. So i think that for a racing motor where max hp is the need yes, but for daily ride maybe yes, maybe no OK, I see your point. I just figured the pick-up tube for the new oil pump would reach down to the lowest point in the sump which should always have oil even in very hard leaning turns. If it does not do this then you are right that air could be sucked into the system and whip the oil into a froth which would make the stock oil pump ineffective. IF I ever used a system like this, I would make sure it reached all the way to the bottom or I would not install it. Thanks for bringing this up. Bill |
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Post by katt on Aug 2, 2018 17:07:11 GMT -5
With both option and i think especially the second, oil may get air bubbles in it and it is more likely to kill your engine You mean microscopic ones, not sure what causes that perhaps if you use fast flow pump?
I know oil manufacturers use additives to prevent this bubbles, but over time oil wears out esp when overheating and more prone to problems.
My main concern however if cooling system sucks a lot of air inside from crankcase and it stays trapped inside cooling radiator or hoses then amount of oil in engine will raise above what it should be therefore need to design it properly.
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Post by gouvis on Aug 2, 2018 17:36:34 GMT -5
The way this oil cooler circuit will work may not be able to to pump oil when the scooter leans for a turn. It will suck air and return it back to your oil pan next to your mechanical pump. That's why i told that i don't like this method much. I may be wrong but i wouldn't try it because i usually ride my scooter roads with turns but if you ride it most on flat straight roads it should be okay. Also i find the oil cooler a little bit unnecessary. I leave in Greece and the temperatures here are now almost 40 celsious. I do almost 50-100kmh a day and my scooter is 50mm with a naraku crankshaft. It has almost 30000km. I build this engine about 26 months ago and i run wot almost all time. I use motul 10w-40 scooter and i run a little richer. Oil changes every 1000-1500km. Now after all this abuse i will replace my piston and cylinder because i get a little oil consuption. So an oil cooler will benefit an engine like this but it will add complex and maybe issues. So i think that for a racing motor where max hp is the need yes, but for daily ride maybe yes, maybe no OK, I see your point. I just figured the pick-up tube for the new oil pump would reach down to the lowest point in the sump which should always have oil even in very hard leaning turns. If it does not do this then you are right that air could be sucked into the system and whip the oil into a froth which would make the stock oil pump ineffective. IF I ever used a system like this, I would make sure it reached all the way to the bottom or I would not install it. Thanks for bringing this up. Bill As i'm think it right now the gy6 is and an engine that does need oil pressure to work as every bearing is ball bearing and not plain bearing. So this engine doesn't need oil pressure to work just pumps oil to ball bearings. That's why i think air bubbles maybe not be a very big issue in the end. The only problem finally is the complex of the system and a possible leakage, especially if the hose are under the pan just like the common oil coolers that goes to the drain plug. Some version of the gy6 150 has oil cooler plugs on the crankcase after the oil pump. That's a better way but i don't know if a simillar mod can be done to the 139qmb. |
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Post by dexameth on Aug 3, 2018 14:15:31 GMT -5
I was going to drill and tap my case for the oil cooler hookups like the GY6 motor kits have, but then after studying it for a few days I came to the conclusion that the ports in the case are too small to be tapped like the GY6. I then studied the plug adapter, saw how it works...
-The pump will pull oil from the case and thru the filter screen and then up thru the pump and towards the crank/cam area.
-With an oil cooler hooked up, it will be drawing oil from the case, thru the plug adapter and into the cooler, back up thru the plug adapter and into the pump, then towards the crank/cam area.
-There is no pump pick-up tube other than the porting in the case that draws oil from the lowest part of the case, so turning or wheelies wouldn't starve the pump.
Sorry if my rambling is bad... I took pictures of the case but I'm failing at showing the oil path thru the system. One thing I did learn is to run the banjo bolts DOWN on the radiator. That way if any air gets into it the pump won't be sucking air from the radiator which would in turn starve the motor from oil and, yeah. No good. With the banjos facing down, even if a little air gets in the system then the pump would still be sucking oil. The only issue is the radiator cannot be higher than the sump or it would all flow in at rest and flood the crankcase with oil. I'll be positioning mine, center of radiator just below the crank shaft in front of the motor on the floor board. This way I won't get much flow-back and it will have good airflow.
Now to just make the mounting bracket, everything else is easy-peasy.
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Post by GrumpyUnk on Aug 6, 2018 13:42:22 GMT -5
q A simpler solution might be fitting an 'extension' oil pan that allows for more lubricant. The drain plug could be substituted with a fitting leading to an add-on allowing extra capacity.
If you used some tubing, you could get siphon movement with a tube-within-a-tube, one exposed to the hot oil, thus absorbing heat, which expands the oil and makes it lighter than the non-heated oil. Less dense oil will float atop the cooler, dense oil. Do the plumbing and you get free circulation. Just ask Henry, as his model T had thermo-siphon cooling only. I have not planned out the hot/cool tube plans.
A second possibility would be to have the oil pumped up to the rocker arms/cam take a longer route back to the sump. If the engine is running, oil is being slung against the inside of the cam cover. Collect that and route it through finned tubes on its way back to the sump, or add some finnage to the cam cover. It could then be cooling the oil before it gets back to be re-circulated. Even drilling and tapping a hole in the lower front edge of the cylinder head in the cam area, and then having the oil that flows through it route through some copper tubing(image of white lightning still copper coil condenser here) coiled to add cooling surface are could decrease temperature without use of another pump. If determined to have airflow, then make a small radiator that could cool the cam oil that is above sump level, but out in the airflow created by motion. Imagination is the key to invention?
tom
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