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Post by jeff84 on Nov 19, 2017 22:00:41 GMT -5
I notice most all 4 stroke scooters have an open oil port on the head. anyone ever used this port for an oil pressure guage? do these engines even produce enough pressure to measure?
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Post by gsx600racer on Nov 19, 2017 22:32:57 GMT -5
My guess is the oil pump supplies enough pressure to keep the top end(cam, rockers, valves) lubricated. If there was a factory oil cooler, then Id say the pressure would be more to oil cool the engine.  I have yet to see an oil pressure gauge on a 49cc build. |
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Post by jeff84 on Nov 19, 2017 23:06:56 GMT -5
I'm working with a 287cc engine, but its the same basic design as a 49cc. I have seen scooters with an oil light on the instrument cluster, but don't really know if they were actually functional. my piaggio has an oil light but its not real
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Post by jeff84 on Nov 19, 2017 23:09:26 GMT -5
i am worried about my rtv clogging an oil passage. being able to monitor oil pressure would be nice
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Post by cagiva4ever on Nov 23, 2017 10:18:36 GMT -5
..... I have seen scooters with an oil light on the instrument cluster, but don't really know if they were actually functional. my piaggio has an oil light but its not real 139QMB's like Peugeot v-clic / Qingqi Qm50qt-6 -a /german rex rs450 Qm50qt-6a etc same models have this FAKE "oil light". it is only a reminder to check oil level amount in engine, by every 1000kilometres. on year '04-'06 Qingqi Qm50qt-6 , the "oil light" is a fully mechanical separate odometer, next to real Odometer. Same gears same mechanics, only difference basically being that "oil light" odometer takes Count-drive from the real odometer, for 1000km. When its reached, a "colored" part of the odometer turn gear points up, and shows on tacho at color Green, on the "peak hole" on Tacho face on bottom LH. Zero/reset button hole is facing towards driver on the fairing part.... later they have changed this mechanical odometer gear assy into LED and LED is on top RH-corner on tacho. i have these both model tachos, about 5 tachos in total. LED version i havent taken apart yet. so this is not oil pressure indication light function at all. i have 139qmb CoC manufac approval papers, that IIRC state oil circulation volume to be 3,8-litres/1-minute. if you have no pressure Psi data, compere that Litre volume to some other known Application engine that has working Pressure meter, and compere oil volume... that could indicate if 139qmb has proper Psi for oil psi meter to work... |
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Post by lostforawhile on Nov 23, 2017 15:43:01 GMT -5
where is the port? my guess would be the port would have BSP threads, as most asian engines do.
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Post by jeff84 on Nov 23, 2017 16:23:52 GMT -5
om the ebgines I gave seen it runs through one of the head studs where oil is fed to the cam journal. and has a bolt to plug it.
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ScooterWes
Scoot Junior
Posts: 9 
Location: Forest Hill, Md.
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Post by ScooterWes on Dec 1, 2017 6:29:55 GMT -5
I recently did a 72cc Big Bore Kit and pretty much replaced part for part. The oil pump definitely works as it poured out about a pint of oil in 10 seconds at first startup. I thought I was in the deep end until I saw where the oil was coming from. When I first started it, oil was pouring out of a hole in the top side of the jug. There was a tapped hole in the jug that was not in the original jug so I plugged it with a screw short enough to ensure it did not block the oil passage and a rubber washer. I think it was a M6 or M8 screw thread. It is a straight threaded hole not a pipe thread (NPT or BSP). I think that hole is probably for some kind of oil sensor. I am glad that I used assembly lube during assembly and did not damage anything. I have put about 500 miles on it since the build and I am very pleased with the results.
Never a problem, Sometimes a challenge, Always an adventure
49cc TaoTao Zummer
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Post by lostforawhile on Dec 1, 2017 18:30:55 GMT -5
Do you remember the thread and pitch? I could machine an adapter that will screw into the head, I want to add a gauge to mine
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Post by cagiva4ever on Dec 14, 2017 18:42:34 GMT -5
apparently NOT all 139QMB cylinders have the "Option" for oil Psi sensor attachment.for example some "recently" re-produced 44mmd diam cylinders are without it. where as all my 2004 made 44mm diam cylinders do have it as Option.
at my '04 44mm diam cylinders, there is only 1 resonable Option for Adapter size Thread (has to be DIY made), and its M6x1 STD default. if using M8x1,25 STD default or any other M8, there is not enough material left, only like 1,5mm wall thickness left in Case of making M8 thread into Cylinder Psi outlet.
carb seems to be "on the way obstruction" of the Outlet, hence looks like Adapter needs to be "well made"....... based purely now looking by Photos, as no engine or Scooter at my nearby "in hands".
i have now got an interest into this subject, and im planning on Producing "adapters" at my ex-machinist school.... as i have already other bits on a way to be Produced there.....
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Post by cagiva4ever on Dec 21, 2017 9:51:55 GMT -5
found today at web, for Gy6, outcome not enough usable Psi: www.scooterinvasion.net/forum/viewtopic.php?t=3488thoughts an issue ? and other finding: apparently Toyota and Subaru have M6x1mm on/off warning light sensor. -"Toyota 4cyl engine's have an M6 sensor that's set to trigger at 5.7psi."
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Post by jackrides on Dec 21, 2017 12:56:09 GMT -5
Try a 0-15 psi gauge. (Does anyone know what a 2 cycle engine is? [steam maybe?] {I know what a 2 stroke engine is.})
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Post by cagiva4ever on Dec 22, 2017 9:00:45 GMT -5
Where to find 0~15 0~30Psi "electrical" tacho gauge ?
eBay has 0-15Psi gauges only as "AirCompressor" type gauges etc. Which is not what we us are looking for, as a Tacho instrument....But if that is the only item ever availabe then it is what it is....to be "hose modded and Routed....."
ideally, ^^ "mechanical long hose" version either isnt "well" suited for use......
are options now limited.... ?
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Post by GrumpyUnk on Jan 4, 2018 8:58:36 GMT -5
When considering oil pressure, you have to remember pressure develops where there is a restriction.
The cam followers/rocker arms only have the restriction around the shaft they move on. That's it.
There is not enough restriction to develop 'measurable' pressure. Sure, there is some pressure, or the oil won't flow, but you won't develop 'oil gallery pressure' like you do in a car or truck engine.
Adding a pressure gauge to a QMB/GY6 is like adding a pressure gauge to the rocker arms on a '56 Cadillac. There's enough pressure to push oil out around the rocker pivots, slop some onto the top of the rocker arm so it can dribble down and lube the valve stems, and finally there's an 'overflow' tube that allows the excess to drain back to the sump after the rocker shaft has filled with oil. Ain't no pressure.
If I were concerned, I'd make sure that my breather was protected(raised and filtered?), that I did not open the dipstick tube in messy locations, and that there were no other openings to the sump. If the oil cannot get out, dirt cannot get in and plug things up.
The manual does suggest measuring the internal clearance of the pump rotor vs housing, and replacing the pump if it is too large. Reasonable suggestions. My thought is the pump is the best-lubricated part of an ICE piston engine, so should wear out last of all wearing parts. Keep the oil changed regularly, use good oil, choose a viscosity that fits the temperature expected, be clean when doing changes, and go ride.
tom
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