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Post by KSR Moto on Sept 12, 2018 12:56:10 GMT -5
I picked up a junkyard 139qmb,it had a burnt exhaust valve and a 47mm bbk installed, the bore was severely scored and the oil had really strange smell
However the crank was good so I replaced the head along with new 47mm bbk
It started at the first try but I am afraid that the internal oil pump may not be working
How do I check the oil pump?
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Post by lostforawhile on Sept 12, 2018 13:55:32 GMT -5
I would have taken the pump apart to check for debris anyway,since the block was scored I would bet on the pump being bad as well
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Post by dexameth on Sept 12, 2018 14:13:02 GMT -5
The oil pump is located inside the case behind the fan/flywheel/stator. You'd have to pull all that off to get to it. You could pop the cam cover off and crank it over and it should squirt oil up to the rockers, but you won't be able to tell if there's anything contaminating the system like lostforawhile mentioned. |
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Post by lostforawhile on Sept 13, 2018 9:26:04 GMT -5
Usually in a failure there is debris circulated or a pump failure caused the engine failure in the first place
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Post by KSR Moto on Sept 13, 2018 14:25:47 GMT -5
Usually in a failure there is debris circulated or a pump failure caused the engine failure in the first place I agree,but I dont have a new seal for it right now if I remove the stator plate |
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Post by jackrides on Sept 13, 2018 17:16:29 GMT -5
Seals do not always have to be replaced when removed if the shaft it slides over is smooth.
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Post by dexameth on Sept 14, 2018 8:26:29 GMT -5
Seals do not always have to be replaced when removed if the shaft it slides over is smooth. Agreed. Kept originals in after upgrading the GY6 to 170cc, and no oil leaks yet. |
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Post by GrumpyUnk on Sept 14, 2018 11:53:52 GMT -5
If you remove the spark plug and the cam cover, and then crank the engine for a short while, you should see oil coming out the passage to lube the rcker arms/cam followers. The same oil is also fed to the big end of the connecing rod per the engine diagrams.
A scored cylinder does not indicate anything about the pump, and is generally unrelated. The cylinder wall gets lubricated by splash from the crankshaft, which is the only method the main bearings get lubricant. The oil control rings are supposed to wipe the majority of said splashed lube back down the cylinder into the sump.
You likely get scoring when things get too hot, or there are mechanical bits that get stuck between piston and cylinder wall. Overheating is also a cause for scoring. Lack of lube or low level will reduce splash, and thus also lead to scoring if allowed to remain so.
Even with the shroud removed, a piston can get so hot that it 'grabs' the ring, and melts together, leaving very little scoring. It will not start or will run poorly with reduced power in that case, but should still do nothing to the oil pump.
If this thing sat in a boneyard, I would want to drain the lube oil and inspect for particles. I would consider using some flushing agent through the jug opening before installing a replacement, catching the flushing agent and again checking for sparkles or flakes. Hope to find none...
The 'filter' screen installed will gather larger bits, but small ones will pass through. I would want to inspect the 'filter' screen before putting much time, effort or money into it. If clogged or having evidence of failure, punt and find another one to fiddle with. Given a new engine can be had for something over $200US, complete, working with junk is sometimes a waste of time. But, many things are thrown away and discarded with a lot of useful life. The labor cost to repair can be persuasive when any repair is performed by a profexxional mechanic. Professional being the taking of money for acts performed... not necessarily indicating performance of said acts properly. Some are great. Some should be asking 'Would you like fries with that?' as their productive task. Either way, if you stay ignorant, you will pay someone to do work that could be instructive and rewarding. My figuring is you choose to learn, or you choose to pay. Works for me.
tom
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Post by KSR Moto on Sept 14, 2018 13:10:07 GMT -5
Here is the update: I disasembled the WHOLE engine and cleaned everything, no signs of bearing failure or pump failure so I rebuilded engine and it runs perfectly for a scrappy scoot, I conected only the necessary things to keep it running It has a 47mm bbk and head with bigger expansion chamber youtu.be/9KPhJrhwr4c |
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Post by GrumpyUnk on Sept 16, 2018 9:56:57 GMT -5
Sounds as if it is running very well. I think I would be closing the valve clearance a little bit, but other than that, good. May want to flip the CDI upside down if you'll be running in any sort of liquid sunshine. Splashed water will tend to fall into the connectors, and may provide unwanted conduction, perhaps causing misfire.
tom
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