Walbro carb inlet needle pop off pressure
11-07-2004, 07:25 AM
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Walbro carb inlet needle pop off pressure
Recently I have taken an interest in better understanding my Walbro SDC-80 carburetor. After some study of the aerocorsair website, the tool to measure the height of the inlet needle's operator arm (part #500-15) relative to the body and a pop off pressure gauge were aquired. When I pressurize the the inlet circuit via the fuel nipple I am unable to make the needle pop off which I expected to happen at 10-15 psi. High and low needles are open 1 1/2 turns. This is a unit I rebuilt and is therefore dry and I am aware of the recommendation that this test be performed when the carb is wet, but...
The result was the same with the cover plate and diaphragm installed and taken off. Can someone explain to me simply how they test a Walbro carburetor's pop off pressure?
Chris Hogan
Miami, FL
The result was the same with the cover plate and diaphragm installed and taken off. Can someone explain to me simply how they test a Walbro carburetor's pop off pressure?
Chris Hogan
Miami, FL
11-07-2004, 09:43 AM
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RE: Walbro carb inlet needle pop off pressure
Most chainsaw carbs will run fine up to 20-25 lbs pressure. If you want to fine tune it, cut 1/32 of an inch at a time till you get down to 15 lbs. Wet the needle valve tip with oil so it doesn't stick. Only to be done with a pressure gauge so you know where your at. By the way, ran a small motor shop for 35 yrs.
11-07-2004, 07:39 PM
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RE: Walbro carb inlet needle pop off pressure
Why not check out this article?
http://www.geistware.com/rcmodeling/...n_pressure.htm
http://www.geistware.com/rcmodeling/...n_pressure.htm
11-08-2004, 07:39 PM
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RE: Walbro carb inlet needle pop off pressure
hello- try a go-kart shop they use a pump to check popoff it can be adapted to the smaller carbs they are petty reasonalable. good luck Erik58
11-08-2004, 09:21 PM
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RE: Walbro carb inlet needle pop off pressure
Raising or lowering the pressure is like raising or lowering the float level on a bowl type carb. It can be put to good use, for instance, if you have an engine with poor vacuum such as an oversize carb, it would help to use pressure at the lower end of the scale as it's more difficult to open the needle valve at the lower pressure.
Brian : Baffles me in the morning too.
Brian : Baffles me in the morning too.
