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Post by bigmac on Nov 17, 2013 19:30:02 GMT -5
Strange. Remember those old TVs that you'd slap your hand against when the picture got snowy and it'd clear up? Seems that hit it and abuse it approach worked on my scooter.
I would never do this normally, but because I was so angry with it, I revved the engine really hard with its rear wheel off the ground. For some reason it didn't stall as it normally would've after being revved. I did it a couple more times and it seemed to idle better with each fast rev. Then after that, I checked the spark plug and found it clean and dry.
Unfortunately, it's still having some issues (possibly do to a vacuum leak) but the oily stuff has apparently disappeared which is very relieving.
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Post by bigmac on Nov 10, 2013 19:02:00 GMT -5
The cover and its baffles looked fine.
Even if I bypass all the vacuum lines it still idles poorly and always stalls if brought to an idle after revving.
While it was idling I took a totally transparent and clean hose and put it into to the air intake manifold. The engine stalled as soon as I put the other end of the hose against the vent opening on the cylinder head cover and I didn't see any moisture in the hose. It's like the gases that come out of the crankcase vent will stop the engine if they enter the air intake, even if for just a few seconds.
There also seems to be an excessive amount of water in the crankcase. If I leave a hose on the cover's vent for a few minutes, the hose becomes very wet inside and starts to drip out what appears to be water on its open end. Tried new gas but that didn't change a thing. Tried to look up information but every search result is about leaks in liquid cooled car engines.
Not sure where to go from here.
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Post by bigmac on Nov 9, 2013 16:06:20 GMT -5
Nothing was oily inside that round plastic part. A tiny amount of liquid came out when I first applied suction to that opening under the CVT cover but nothing else will come out now. I noticed that unhooking all the vacuum lines kept the plug dry and the engine running better. So I hooked up one line at a time while giving the engine some time to run after each hook up. The plug stayed dry until the breather hose on the cylinder head cover was attached. This surprised me because I don't see oil coming out the cover's vent. Plus, any oil would need to go through an oil catch canister and air filter. I hooked a clear hose to the cover's vent and put the other end into the air intake manifold. It ran terribly right as the engine started. I had to hold the throttle open some just to keep it from stalling. This is the plug afterwords (camera focused on the background instead, but it's not too blurry to see):  It was wet and black in some areas. Here's the spark plug hole:  The oil seems to leak out from around the plug. I don't know how since the plug is in there nice and snug. The clear hose had moister in it, but it was clear like water. I also found this oily stuff that's a solid shade of yellow weird:  That attaches to the oil catch canister. My plan now is to inspect inside the cylinder head cover. |
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Post by bigmac on Nov 4, 2013 19:49:48 GMT -5
This is what I have:  On mine the hose attached to the bottom of the cover goes to the hose that connects the air box and carb. Also have the charcoal and oil catch canister on mine. Removed the cylinder head cover today to inspect its EGR setup. Found nothing wrong nor any oil. Even removed the hose that brings the recirculated exhaust gas to the carb, but nothing. Just one last thing I can check now before considering this an unsolvable mystery. A hose goes from the top of the air box to a round plastic thing (picture below).  I took this plastic thing apart once. Three hoses attach to it. As I already mentioned, one of the hoses goes to the top of the air box. A second hose goes to the intake manifold so suction will open a diaphragm while the engine is running. The Third hose goes all the way down to the transmission assembly. It attaches under the back side of the CVT cover (picture below).  The hose is unattached in the picture. I hooked a clear hose to it and applied suction and saw some liquid get pulled into the hose. Perhaps the hose on top of the air box is sucking oil (gear oil I'd assume) from the hose that connects under the CVT cover. |
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Post by bigmac on Nov 3, 2013 17:47:59 GMT -5
Think we got a break in solving this mystery.
Took out the air filter today and looked around inside the box that houses it. Everything looked normal in the box itself but the hose that connects the box to the carb appeared to have oil in it. Rubbed a finger in the opening of the hose and found reddish colored oil on it and quite a bit.
Only one hose connects to the hose that runs between the air box and carb, and that's a hose for the EGR (Exhaust Gas Recirculation). Oil is well know to travel through the vent hose on the cylinder head cover, but I never heard of oil traveling up from the EGR valve on the cylinder head cover.
The engine started and ran better with the EGR hose unplugged. The spark plug was also not oily afterwords, so it may not be an internal engine problem after all.
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Post by bigmac on Nov 2, 2013 18:28:06 GMT -5
The timing of events seem too odd though:
- Engine won't idle and oil is on the plug.
- New rings and head gasket, no change.
- disassembled head and clean it then it idles and there isn't any oil on the plug.
- About 350 miles later the engine won't idle and oil is on the plug, again.
- Put in new head and nothing changes.
Those new rings seemed fine. In fact, the oil level would always go down some every 100 miles when I got the scooter (odometer had around 500 miles when I got it), but the oil level didn't appear to go down any after the new rings. Hard to believe they would work fine for about 350 miles then suddenly break or become worn out.
As for the cylinder, the areas that had not worn from ring contact were visible but didn't appear to have a ridge between them and the areas that had ring contact. It was all smooth. You could drag a fingernail down the cylinder wall and not feel any ridge as it passed onto the unworn areas.
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Post by bigmac on Nov 2, 2013 0:29:39 GMT -5
The shorter valve stems worked with the new rocker arms. I prefer the longer stems though. It's easier to set the valve clearances when the stems stick out of the cylinder head more. Had to bend the feeler gauge some to slip it in.
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Post by bigmac on Nov 1, 2013 19:09:53 GMT -5
Odometer had 2,383 miles when the new piston rings were put in (I took note) and it's now at 2,802. Gave it a hard break-in during those miles, especially the first 200. Lots of engine loading and braking and rpm changing. Have been using Rotella triple protection 15w-40 motor oil since I got the scooter and during the break-in.
Didn't have a honing tool and didn't want to buy one or a new cylinder so I cleaned and inspected the old one. I pressed each of the new rings into it to check ring gaps and fitting. Everything looked good. Following a GY6 repair manual, I put in the new piston rings.
Even without a re-honed cylinder, I can't image that those rings would be worn out after only 400 miles.
The vent hose appears to be fine. I unhooked it with the engine running so any crankcase pressure would have nothing to block it but it made no difference. I also put some Sea foam into the crankcase and saw liquid (I assume the Sea foam) come out the tube that collects liquids blown throw the vent hose. Lots of white smoke blew out the exhaust on the following start up which confirms a leak between the crankcase and combustion chamber. Only Sea foam could make that much white smoke.
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Post by bigmac on Nov 1, 2013 0:58:31 GMT -5
Had an oily spark plug. Put in a new piston and rings and head gasket but that didn't fix it. Next I removed the cylinder head and its valves for an inspection and cleaning. Didn't replace the head or anything on it, but afterwords the problem went away.
After about 350 miles, the plug got oily again. So I'm thinking, "Well, the cylinder head must have bad oil seals or something." So I buy a new ready to go cylinder head, valves and everything already installed. I slowly and carefully install it, making sure everything is done correctly. Alright, so piston rings, check, head gasket (I put in a new one when installing the cylinder head), check, valve oil seals, check. I start it up for a few minutes then check the spark plug... yep, oily.
I can't deal with this anymore. Could I just put in thicker motor oil and hope it can't leak throw whatever spot the oil is getting in from? What's the worst that can happen? Damage the engine, thing is already junk. Also, does anyone have a possible explanation for this? The oil magically makes its way from the crankcase into the combustion chamber in a seemingly perfectly assembled engine.
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Post by bigmac on Oct 22, 2013 16:19:25 GMT -5
Ended up getting 64mm valve stem compatible rocker arms on ebay for $19.  with free shipping. There was a cheaper seller in China, but I don't feel like waiting 1 to 2 weeks. Weather here is mild during the day and cold at night now but soon will be cold all the time so I want to get this thing finished. Guess my 69mm rocker arms can be cleaned, oiled, and stored away for any possible future use. |
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Post by bigmac on Oct 21, 2013 20:40:38 GMT -5
I think you're right.
I compared the two heads just now and size wise, they appear to be identical to each other. The camshaft sits at the same height in both heads so I don't think the camshaft chain and/or crankshaft will have issues with the shorter valves.
By the way, this is a completely stock 50cc in case anyone wants to know.
Seems everywhere I look, the valve stems and rocker arms are either 64mm or not specified. In my case, the seller didn't specify and I ended up with the 64mm. I found only one seller on ebay with rocker arms for 69mm valve stems and wants $120 for them. Wow, are these rocker arms rare or something?
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Post by bigmac on Oct 21, 2013 18:18:58 GMT -5
I ordered a new cylinder head but the valve stems are shorter than the ones on my original head. My original head has 69mm valve stems and the new one has 64mm stems for some reason. This is a problem because the rocker arms will not work with these shorter valves.
Would getting rocker arms that work with 64mm valve stems be the correct solution or would other engine parts need changing as well?
Is there any difference between the two lengths in terms of engine performance? If not, then why would they make valve stems different lengths? It's a huge headache.
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Post by bigmac on Sept 6, 2013 0:07:21 GMT -5
What a terrible buying experience.
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Post by bigmac on Aug 28, 2013 20:14:56 GMT -5
Thumbnails for other videos appeared after watching, one titled "exhaust slightly overdone".
That looks hilarious!
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Post by bigmac on Aug 26, 2013 19:08:56 GMT -5
The screws on top of my carb were also stripped when I got my scooter. I bought a new carb on ebay for $24 and the carb has been working great. The choke is located on the back left corner of the carb. It should have a black plastic cap over it. Pull the cap off and you should see two screws holding a metal clip which is holding the choke on. Careful, those two screws may strip very easily when you attempt to remove them. After removing them and the metal clip gently pull the choke out. If it is stuck, it will not slid out of the carb easily. If it feels stuck, I would pull the choke out then put it back into the carb and then unplug its connector and start the bike. This is a photo I posted on another thread of two chokes of mine. The part that the needle comes out of is what could be stuck.  |
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with free shipping. There was a cheaper seller in China, but I don't feel like waiting 1 to 2 weeks. Weather here is mild during the day and cold at night now but soon will be cold all the time so I want to get this thing finished.