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Post by rickisan on Apr 28, 2019 23:06:50 GMT -5
A slow gas leak is coming from below the engine area. Upon disassembly it was found the Needle Valve may have a problem. Shouldn't the Needle Valve pictured below have a rubber tip? It has a sharp metal point only. No rubber on the tip. I am new to scooters and wanted to check to be sure. Also, what is the best source for replacing the Needle Valve only(if needed). Thanks!  |
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Rune 75
Scoot Enthusiast
Posts: 441
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Post by Rune 75 on Apr 29, 2019 3:17:25 GMT -5
When the needle looks like that there is an o ring in the hole where it goes. Often it just needs a good clean. If something is stuck in/around the o ring it won't seal properly.
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Post by rickisan on Apr 29, 2019 7:01:58 GMT -5
Rune 75 thank you for replying. Looking down in to the hole where the needle valve operates there is no O-ring or "shelf" to place an O-ring. If the needle valve did have a rubber tip... the hole appears way too large to be sealed by the needle valve only. It seems like there may be some type of rubber insert piece that is missing. I would like to approach this from another direction. If the carb can be identified a rebuild kit should have the correct part. The only markings on the unit are "MIKUNI corp" and "H2". Any help with carb identification will be much appreciated.  |
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Post by rickisan on Apr 29, 2019 7:22:23 GMT -5
OK I am an idiot... found the needle valve and seat(which I removed yesterday) available on get2itparts. It appears the valve point does indeed have a rubber tip as shown below.  |
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Rune 75
Scoot Enthusiast
Posts: 441
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Post by Rune 75 on Apr 29, 2019 8:26:59 GMT -5
 This is how it looks like when there is no rubber tip. Not exactly like an o ring but close. |
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Rune 75
Scoot Enthusiast
Posts: 441
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Post by Rune 75 on Apr 29, 2019 9:03:10 GMT -5
Couple of years ago i when I was cleaning the carburetor on our snowblower, with pressurized air, I blew that o ring out of the carburetor and into/onto the gravel outside the garage. Immediately started searching for it, no luck. Had to by a complete rebuild set just to get that o ring.
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Rune 75
Scoot Enthusiast
Posts: 441
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Post by Rune 75 on Apr 29, 2019 9:07:13 GMT -5
OK I am an idiot... found the needle valve and seat(which I removed yesterday) available on get2itparts. It appears the valve point does indeed have a rubber tip as shown below. Ok, so you removed that seat yourself ? Not that one the picture of course but a similar one ? Aren't there any rubber inside it ? |
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Post by rickisan on Apr 29, 2019 11:34:16 GMT -5
Rune 75, Yes I removed the valve seat and there is no rubber ring. Thanks again for all your help. Rickisan  |
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Post by rickisan on Apr 30, 2019 7:14:23 GMT -5
Okay so pretty sure it is a missing the “needle valve seat o-ring” for lack of a better phrase. What is a good source for carb rebuild kit? The get2it parts people seem to be reasonable. Any other suggestions are very welcome.
I am gonna call several and see what’s up. If calling is still an option.
The other thing is identification of the carburetor. The identifying information so far is: 18mm Mikuni Corp. from a E-ton Beemer. It has an “80” main jet. The marking “H2” is stamped in the “roof” of the bowl chamber. There are also numbers on the side of the brass cylinder valve seat. Very faint and difficult to read. Something like “671.2”.
Ok well any comments very welcome
Thanks again Rune75
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Rune 75
Scoot Enthusiast
Posts: 441
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Post by Rune 75 on Apr 30, 2019 11:32:16 GMT -5
Done some reading on the subject. Seems like these metal to metal type of valve is quite common. So you are not missing anything, it's supposed to be like that. Apparently it seals good enough. When the engine is running it consumes way more fuel than that valve lets pass when it's closed, if it even passes any fuel.(of course the valve and seat needs to be absolutely clean and not damaged) When the engine is turned off the vacuum operated pet cock/fuel valve is locked so no fuel enters into the carburetor and therefore prevents any leaking/leaks.
From where on the carburetor is gas leaking out ?
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Post by rickisan on Apr 30, 2019 18:22:39 GMT -5
I am not exactly sure where the leak originates from. I bought the bike about 3 mos ago. Previous owner said it had a carb leak and the carb was replaced but the leak persisted. I brought it home and put 1/2 liter of gas in the tank and it leaked out over the next 3 or 4 weeks. Very slow. An ounce or less every day. Exactly like the seller described.
Since the carb is off the bike adding a little gas to the tank to see if it is leaking past the vacuum valve seems a good idea. I am planning to replace the vacuum actuated fuel valve with a manual valve soon. It will be nice to know if it is leaking.
I will let you know what happens.
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Post by rickisan on May 4, 2019 14:16:15 GMT -5
A pint of gas poured in to the tank of the scooter is producing a slow drip of fuel out of the gas supply line where it would normally be connected to the fuel input nipple of the carb. I will install a manual cutoff petcock and block off the vacuum hose nipple from the intake manifold/carburetor. Test and report back the result.
Thanks again Rune75. Cheers!
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Rune 75
Scoot Enthusiast
Posts: 441
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Post by Rune 75 on May 4, 2019 14:57:37 GMT -5
A pint of gas poured in to the tank of the scooter is producing a slow drip of fuel out of the gas supply line where it would normally be connected to the fuel input nipple of the carb. I will install a manual cutoff petcock and block off the vacuum hose nipple from the intake manifold/carburetor. Test and report back the result. Thanks again Rune75. Cheers! A manual petcock will most likely solve the problem. |
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