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Post by 90GTVert on Oct 3, 2015 21:27:18 GMT -5
Are you sure it's gas and not oil on the valve cover?
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Post by astray on Oct 3, 2015 21:30:33 GMT -5
I don't know how to check for sure, but I think it's gas because that yellow colored line used to be completely clear and changed to the color it currently is. Not sure if oil would reach a hot enough to temperature to discolor that line.
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Post by 90GTVert on Oct 4, 2015 8:12:55 GMT -5
Your oil could be 250F or hotter. Gas really shouldn't be in that line, and hopefully it's not 200+F just hanging around in the carb.
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Post by Fox on Oct 4, 2015 11:42:38 GMT -5
That tube is the vent for the crankcase. When your engine fires each time, that gas explosion sends the piston downward with force and most of those high pressure gasses are kept in the cylinder by the piston rings but a small amount of them do blow by the piston rings and down into the crank case. That happens thousands of times a minute. This pressurizes the crankcase and if not relieved, that pressure would build up in there and pop out the crank seals which is not a good thing so they have this vent on the valve cover to relieve the pressure.That's why you can feel and hear the gasses flowing out of the vent when you disconnect the hose from the valve cover while the engine is running. There is oil being pumped up into the valve cover area to lubricate the cam and rocker assy's. At wide open throttle a relatively small amount of that oil can make it's way to the vent tube and it gets sucked into your intake and through the carburetor from the way yours is set up. That oil is colored and very hot so it's no surprise that a clear tube would change to the color of motor oil. In colder climates water vapor can condense inside the crankcase and it too comes out of the vent. This oily, water vapor spray is some of the nastiest smelling stuff ever. I for one don't like having oily watery crap running through a carburetor cause it gunks it up over time so I replace and route the vent tube so it runs uphill and vents out into the atmosphere. Other guys and gals have done the same thing in the past. I use automotive fuel line. Others use clear tubing. It doesn't matter. I run the hose up the frame to the fuel tank and let it vent out the back of the scooter. Some guys will put a fuel filter or a small breather filter on the end. This uphill slope will allow the fumes and water vapor to escape without gunking up the carb and the oil pretty much stays in the engine where it belongs. There's a whole thread about alternative venting. 49ccscoot.proboards.com/thread/997/crankcase-ventingA cheap and effective alternative is shown here. Anything that keeps the oily crap out of the carb and intake is a good option.
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Post by astray on Oct 4, 2015 19:19:05 GMT -5
That was a lot of useful information, I've got plenty of fuel line left so I'll probably just run a really long line uphill to the gas tank and put some sort of filter on the end of it.
As for the rest of the scooter I'm probably gonna do the BBK either tomorrow or Tuesday (probably Tuesday afternoon because I have an exam at noon that has priority) and go from there. Hoping I don't run into any issues with the parts I've purchased, somewhat worried about the 64mm vs 69mm valves since I got 64 mm valve head replacement and the 1P39qmb sometimes has 69mm valves.
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battlekoozie
Scoot Member
editing videos and searching a for a real job
Posts: 25
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Post by battlekoozie on Oct 5, 2015 21:25:45 GMT -5
Hey on this subject of Valves, can someone suggest a decent price of a "valve job" from a shop in the USA? (sorry to go off subject)
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Post by 90GTVert on Oct 7, 2015 8:34:42 GMT -5
Just judging from what I recall around here, $20-50 seems pretty common. It can vary greatly from shop to shop.
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Post by astray on Oct 7, 2015 18:56:30 GMT -5
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Post by katastroff on Oct 7, 2015 18:59:15 GMT -5
Nothing to worry about.
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Post by Fox on Oct 7, 2015 19:17:52 GMT -5
It's okay to hit that gasket mating surface with fine sandpaper to remove any contaminates and smooth any nicks or abrasions.
I use a product called Permatex Copper Spray on the head gaskets. (auto parts carries it) I hang the gasket up with a bent piece of wire and spray both sides and let it sit for a while til it gets tacky and then install it. It seals up real good.
Don't forget about those little locating dowels!
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Post by astray on Oct 7, 2015 19:23:41 GMT -5
Locating dowels?
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Post by katastroff on Oct 7, 2015 19:32:26 GMT -5
The little pieces of tubing that goes en the long studs to align the cylinder on the base and the head on the cylinder.
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Post by Fox on Oct 7, 2015 19:48:36 GMT -5
Yeah there's a couple on the base, the head and the rocker assy. They only fit on two of the four studs on each layer of the cake.
The rocker goes on withe the "EX" facing down.
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Post by astray on Oct 8, 2015 20:32:48 GMT -5
Welp, the valves were perfectly set at 0.004" when I just checked them so it's definitely not a valve problem. Almost definitely have to rebuild the engine this weekend. Also just like I thought my current head assembly is freaking 69mm and the 47mm Head I purchased is 64mm so I have to order a new rocker assembly and it won't be here until monday at the earliest most likely. I am very frustrated right now lol
Upon further inspection the intake is set properly at 0.004" while the exhaust is at 0.007". Not sure if this would cause the scooter to run like it has, but definitely something I'll be fixing as soon as get my hands on a 9mm wrench (apparently harbor freight doesn't care about this wrench in it's wrench set)
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Post by kagetenshi on Oct 9, 2015 10:46:37 GMT -5
Not just harbor freight, I couldn't find one at any of the auto parts stores around here. Not even at the distribution centers. Heck almost didn't find one at the home depot.
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