Humbling, HDC and HDA Walbro

[Charley K]

Non ethanol gas is @ 91-93, all my small stuff runs well on it. I use it for the carburetor benefits. They all run pretty well on the junk gas, just run it out dry when I'm thru with any of the 2 cycle stuff that are not used regularly. Any benefit from the increased octane is probably wasted on low compression mowers and equipment. The little xl saw has 120lbs compression but it does say on the factory label not to use gasohol. I think that was for the carb and hoses. Most of the fixed timing is usually @ 20 BTDC to TDC depending on the equipment. Some of the older saws would probably like high octane with the higher compression ratios. What does the check valve do in the walbro carburetors and how does it effect the running?

[Oldengr]

The check valve is before the main fuel nozzle and allows fuel into the throat. Based on the amount of throttle it should put in correct amount to keep the engine running. You can find walbro check valves on Ebay. Repair Kits come with a screen for the check valve but under the screen is a small diaphram. If that is damaged then the check valve won't work correctly and needs to be replaced. Rather than buying a new check valve you can make a new diaphram with a hollow punch of the correct size and one of the old carburetor diaphrams. Just punch it out and carefully insert it into the check valve.

[Addem]

Originally Posted by Charley K

could buy them cheaper than rebuild them. That came to an end with xl homelites, if you can find a new

That's been my experience with briggs and stratton on my homelite pumps, which are all 4 cycle. The rebuild kits are over $50, but I bought new Honda and tecumseh carbs for less than $20. My tillotson rebuild kit was $5 with shipping. Go figure.

[Charley K]

Hi, I was rereading some old posts today and run across your answer regarding the carb check valves. Thank You. I noticed some are brass and are destroyed when removed. There is some information and availability but I have yet to repair any of the walbro carbs on the homelite xls. There were about four different carbs, it seems the tillitson was the easiest to get running.

[oologahan]

There is a duck bill valve that will need to be replaced to allow the saw to run, this maybe the check valve mentioned