When I did Maintenance of Carburetor last Spring, I thought that it would be durable for OEM compatibility because Air Screw was airtight so it was a mistake to use it.
While driving around last autumn, opening Throttle to accelerate begins to sound like Knocking and the symptoms worsen further this spring. I was in trouble because I did not understand the cause, but after decomposing my carburetor daringly - - - The O-ring was deformed and crushed.
Apparently because the O-ring collapsed, it seems that the secondary air was sucked in from Air Screw, the air-fuel mixture became thin, causing Knocking.
When I replaced it with a new O-ring of OEM Product, I got no more Pitari and Knocking. (The number of revolutions of Air Screw is the same)
Although the OEM Product before exchange was somewhat deformed, it was not deformed severely so far, so it seems to be hard to resist oil resistance like the company's Float packing as well.
Periodically it will not be a problem to replace it, but since the price is about twice as much, purchasing an OEM product would not be a hassle..
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