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Post by phatboy on Feb 8, 2016 6:18:28 GMT -5
I just bought a new Mikuni carb, wanted something higher quality than the chinese carbs, because my last chinese carb I bought new overflowed from the float after a couple of weeks and no amount of cleaning the float valve and its seat would stop the leak.
Problem is this new Minuki is doing the exact same thing now, though leaking slow about one drip a minute, it's still leaving a pool on my garage floor in the morning.
Trying to figure out what is going on, I thought maybe the fuel filter, it's for a Briggs riding lawn mower, figured it would be fine for a scooter, I looked and it's 150 micron, and standard fuel filters for scooters are hard to figure out but looks in the range 50-100 micron. Just wondering if 150 micron is enough to keep the float valve from sealing. Or if I just got unlucky with 2 bad float needles in a row.
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Post by pistonguy on Feb 8, 2016 8:50:12 GMT -5
Does the Needle have a Viton tip? or Rubberized?
Got two power equipment buds here doing 300-400 new carbs sales a year and 600-800 carb kits.
ETHANOL is great for the repair and replacement business. write your check
Its a Corrosive. had to Flush my Alky motors with Gas after each race, would Destroy a Walbro in less than a week.
This Filth does Not mix well with Gas and separates, if your supplier has not been filled up mixing the full most likely Much more than 10% EA. more like 35%, Then some chase there tales trying to get a carb, jetted and scoot running correctly. same will happen in you gas can at home.
My scoot, CBR and all power equipment is ETHANOL Free. and these problems Don't Exist
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Post by tortoise on Feb 8, 2016 11:43:40 GMT -5
Also check if the carb bowl casting is deficient. If the gasket groove is too deep, it never seals properly.
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Post by phatboy on Feb 8, 2016 16:06:37 GMT -5
By city ordinance all gas here has ethanol, I don't like it but its not practical to have to refuel outside the city.
The new chinese carb worked great but started leaking after a few weeks, it had a metal tipped float needle, and I think a brass seat. Couldn't get this one to ever seal properly again once it started leaking. I need to open up the mikuni and see what it has.
Both the new chinese and the new Mikuni leaked out the drain tube I'm pretty sure it was from fuel going out the overflow tube in the bowl, and the problem wasn't the drain screw.
I wonder if those metal tipped float valves are more sensitive to debris. The original carb that came on the scoot never worked right but also never leaked a drop and it had either viton or rubberized float valve (not metal.)
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Post by ricardoguitars on Feb 8, 2016 16:36:11 GMT -5
Have you checked for vacuum leaks? If you have a vacuum operated petcock, a vacuum leak disables the petcock, since air gets sucked from where the leak is located.
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Post by phatboy on Feb 8, 2016 18:13:13 GMT -5
I have a manual petcock, I gutted vacuum one to always flow when it went bad and could not find a replacement that fit, then plugged the vacuum line. it will eventually stop dripping out when I turn off the gas. but if everything is working right it should not drip at all. Turning off fuel just limits how much leaks out.
I pulled off the float bowl today and yep, it has a metal tipped float valve just like the chinese one that leaked. So probably something to do with that.
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Post by pistonguy on Feb 8, 2016 21:49:00 GMT -5
By city ordinance all gas here has ethanol, I don't like it but its not practical to have to refuel outside the city. The new chinese carb worked great but started leaking after a few weeks, it had a metal tipped float needle, and I think a brass seat. Couldn't get this one to ever seal properly again once it started leaking. I need to open up the mikuni and see what it has. Both the new chinese and the new Mikuni leaked out the drain tube I'm pretty sure it was from fuel going out the overflow tube in the bowl, and the problem wasn't the drain screw. I wonder if those metal tipped float valves are more sensitive to debris. The original carb that came on the scoot never worked right but also never leaked a drop and it had either viton or rubberized float valve (not metal.) City Ordnance? Gotta love being force fed power robbing, fuel gobbling, engine eating, filth. My Ordnance say I can't make whiskey, ya right  |
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Post by rockynv on Feb 9, 2016 1:14:43 GMT -5
By city ordinance all gas here has ethanol, I don't like it but its not practical to have to refuel outside the city. The new chinese carb worked great but started leaking after a few weeks, it had a metal tipped float needle, and I think a brass seat. Couldn't get this one to ever seal properly again once it started leaking. I need to open up the mikuni and see what it has. Both the new chinese and the new Mikuni leaked out the drain tube I'm pretty sure it was from fuel going out the overflow tube in the bowl, and the problem wasn't the drain screw. I wonder if those metal tipped float valves are more sensitive to debris. The original carb that came on the scoot never worked right but also never leaked a drop and it had either viton or rubberized float valve (not metal.) With a solid needle valve there should be a rubber insert pressed into the seat or a loose viteron flat seal that has to be inserted into the seat. If the rubber seat is not pressed into the seat assembly then it will have an o-ring or a potentially green ribbed flat viteron rubber washer for the metal needle to seat against. It should not be metal on metal. |
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Post by phatboy on Feb 9, 2016 3:09:13 GMT -5
both my carbs are metal to metal, had them both apart and it's a steel needle and brass seat, no rubber inserts or anything. I'd never seen this combination before, seems like a really bad design to me, but apparently some people have no problem with this kind at all. I guess metal to metal would be good for ethanol gas though
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Post by rockynv on Feb 9, 2016 5:18:56 GMT -5
both my carbs are metal to metal, had them both apart and it's a steel needle and brass seat, no rubber inserts or anything. I'd never seen this combination before, seems like a really bad design to me, but apparently some people have no problem with this kind at all. I guess metal to metal would be good for ethanol gas though On the Mikuni with the brass seat insert you may find that there us a sandwich of brass with the seal pressed inside it that can be very difficult to see since it is between the end of the seat and a pressed in brass washer or at least this was the case in with power equipment. Turned me off from Mikuni for carbs as the seats were too expensive for the models that we used sometimes making the entire engine not worth repairing for something as mundane as a float seat. On a Kawasaki industrial 6 hp engine in a piece of construction equipment for example some of the Mikuni seats were over $75 so if you had to short block it and replace the seat it could easily put you where it cost less to replace the entire unit. Perhaps there is a viteron tipped float needle that will interchange on yours. |
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Post by JerryScript on Feb 9, 2016 13:12:48 GMT -5
Sounds like the issue is with using a manual petcock. A free flow system like a manual petcock creates can overwhelm the needle under the right conditions. If you still have a stock vacuum petcock, try it and see if the issue goes away.
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Post by phatboy on Feb 10, 2016 23:37:35 GMT -5
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Post by rcq92130 on Feb 11, 2016 1:28:03 GMT -5
Sounds like you, Sir, never ripped out the horse shoot, worthless ChinaHoses on your scooter. These things deteriorate from the inside, so while they look fine on the outside, on the inside they are falling apart, creating globs of dissolved "rubber" that mucks up everything.
Pull that crap out! put in some real fuel hose!
ps: this is no doubt why your needle valves have also been failing. Imagine that crap globbing up the needle valve, preventing it from seating!
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Post by phatboy on Feb 11, 2016 2:29:25 GMT -5
original china hose is long gone, it had some hack job by the previous owner when I got it, thus the new fuel line I bought from lowes. It was made for a riding lawn mower but I thought it would work, guess I was wrong
The new fuel line must be cheap china stuff? screw it, I am going to start over from scratch, ordering some of that translucent fuel line and going to be done with this I hope.
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Post by rockynv on Feb 11, 2016 5:16:23 GMT -5
original china hose is long gone, it had some hack job by the previous owner when I got it, thus the new fuel line I bought from lowes. It was made for a riding lawn mower but I thought it would work, guess I was wrong The new fuel line must be cheap china stuff? screw it, I am going to start over from scratch, ordering some of that translucent fuel line and going to be done with this I hope. Those hoses with that kit are supposed to be made in the USA which is what is printed all over the hoses. What did you use to cut them to length? Some swear by a serrated knife however that will create a bunch of rubber bits that will need to be blown out of the hoses before it can be used. Hopefully it was not ancient pre-ethanol stock that Lowes has had on the shelves for over a decade. |
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