Calling all Walbro carb gurus - see pic's
08-31-2008, 04:33 PM
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RE: Calling all Walbro carb gurus - see pic's
The problem is with the WT201, which has a lean top end. This requires to have the low needle too far open, so it will not balance midrange all that well.
Drilling out the main needle jet to 1.1mm helps a lot. (from my tool box notes)
Drilling out the main needle jet to 1.1mm helps a lot. (from my tool box notes)
08-31-2008, 04:52 PM
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RE: Calling all Walbro carb gurus - see pic's
Yo, PE. You do realise how much of a pain in the arse it is to buy mm (metric) drill bits here?
Near impossible. However Dremel sells a real nice set of wire size drill bits.
Near impossible. However Dremel sells a real nice set of wire size drill bits.
08-31-2008, 05:02 PM
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RE: Calling all Walbro carb gurus - see pic's
Wire sizes are inversed to real sizes, because they are based on a length of wire drawn from a certain weight of metal.. I will leave it to you imperial folks to figure out which is which in relation to diameter.
1.1mm was the size that worked well for me! For conversion: One inch is exactly 25.4mm, so look for a drill of 0.043307086" diameter.
Excuse my sadistic big smile
, cant help myself.
1.1mm was the size that worked well for me! For conversion: One inch is exactly 25.4mm, so look for a drill of 0.043307086" diameter.
Excuse my sadistic big smile
, cant help myself.
08-31-2008, 05:31 PM
#29
RE: Calling all Walbro carb gurus - see pic's
Actually I re-used the pump gasket, I didn't like that blue see-through plastic one. I only replaced the metering device's diaphragm. I'm starting to wonder if the pump is not working as well. It does't seem to give me that squish squish sound I usually hear from fuel getting into the cylinder. I had to flip the prop exactly 20 times to get fuel from the tank up to the carb fuel inlet. It's manual choke so it's not a servo preventing the choke from closing fully. I close it tight with my hand. The engine ran good today. But it takes lots of priming to get it to start the first flip every time.
08-31-2008, 05:57 PM
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RE: Calling all Walbro carb gurus - see pic's
ORIGINAL: pe reivers
Wire sizes are inversed to real sizes, because they are based on a length of wire drawn from a certain weight of metal.. I will leave it to you imperial folks to figure out which is which in relation to diameter.
1.1mm was the size that worked well for me! For conversion: One inch is exactly 25.4mm, so look for a drill of 0.043307086" diameter.
Excuse my sadistic big smile , cant help myself.
Wire sizes are inversed to real sizes, because they are based on a length of wire drawn from a certain weight of metal.. I will leave it to you imperial folks to figure out which is which in relation to diameter.
1.1mm was the size that worked well for me! For conversion: One inch is exactly 25.4mm, so look for a drill of 0.043307086" diameter.
Excuse my sadistic big smile
, cant help myself.
A #57 drill bit is .0430" in diameter.
Mike
09-01-2008, 07:50 AM
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RE: Calling all Walbro carb gurus - see pic's
ORIGINAL: JoeAirPort
Actually I re-used the pump gasket, I didn't like that blue see-through plastic one. I only replaced the metering device's diaphragm. I'm starting to wonder if the pump is not working as well. It does't seem to give me that squish squish sound I usually hear from fuel getting into the cylinder. I had to flip the prop exactly 20 times to get fuel from the tank up to the carb fuel inlet. It's manual choke so it's not a servo preventing the choke from closing fully. I close it tight with my hand. The engine ran good today. But it takes lots of priming to get it to start the first flip every time.
Actually I re-used the pump gasket, I didn't like that blue see-through plastic one. I only replaced the metering device's diaphragm. I'm starting to wonder if the pump is not working as well. It does't seem to give me that squish squish sound I usually hear from fuel getting into the cylinder. I had to flip the prop exactly 20 times to get fuel from the tank up to the carb fuel inlet. It's manual choke so it's not a servo preventing the choke from closing fully. I close it tight with my hand. The engine ran good today. But it takes lots of priming to get it to start the first flip every time.
09-01-2008, 08:54 AM
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RE: Calling all Walbro carb gurus - see pic's
The MVVS 58 appears to have an external pulse line centered on the pump chamber. http://mvvs.nl/
09-01-2008, 09:58 AM
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RE: Calling all Walbro carb gurus - see pic's
All MVVS engines have external pulse lines. The central fitting on the 58 is the pressure reference for the regulator membrane. I fit that to a simple static pitot tube to avoid all carb in-flight problems.
09-01-2008, 09:36 PM
#35
RE: Calling all Walbro carb gurus - see pic's
When they say to set the metering lever height, what exactly do you do to set this? Bend the arm or cut the spring? I see the device for measuring it but they say nothing how to actually change the height.
09-01-2008, 09:37 PM
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RE: Calling all Walbro carb gurus - see pic's
bend it up or down, the spring length has nothing to do with the height of the metering lever... just how hard it's pushed
it's easy to bend, I just use my fingernail or a small screwdriver or something
it's easy to bend, I just use my fingernail or a small screwdriver or something
09-01-2008, 10:55 PM
#37
RE: Calling all Walbro carb gurus - see pic's
Thanks, I kind of thought that. They never really say exactly how to "adjust" it. Maybe I should have one of these devices.
I read that Walbro service manual. They really play down the pop-off pressure. They just say that it should be over 10 psi so it doesn't get over come by the pump pressure. I guess it's because the needles can adjust no matter what the pop off pressure is. They give more importance to pressurizing the carb and submerging it to look for air bubbles.
I read that Walbro service manual. They really play down the pop-off pressure. They just say that it should be over 10 psi so it doesn't get over come by the pump pressure. I guess it's because the needles can adjust no matter what the pop off pressure is. They give more importance to pressurizing the carb and submerging it to look for air bubbles.
09-02-2008, 07:49 PM
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RE: Calling all Walbro carb gurus - see pic's
I played around with pop-off pressure about a year ago and anything from 10 psi to 30 psi seemed to work well. I could not tell any difference between 10 and 30. This was on a Tillotosn carb on a 3W 100. The design principles are the same (Walbro and Tillotson) on their 2 cycle pumper carbs.
