TOPIC: Yamaha rt3 idle question

OK, that tells me that the oring is old, dried, and/or shrunken. I'd get a new oring on there and try it, you shouldn't have or need a gasket there. Also, check the phenolic spacer for damage, that could cause the oring not to seal.

Congrats on making progress!

Early bikes had just a gasket... even though there was an o-ring groove.

If it seals good with both, nothing wrong with that IMHO... even though it might be "wrong".

Here's a post from one of the experts on the topic:

yamaha-enduros.com/index.php/forums/part...1-dt1?start=10#47483

RT3Fan : you are probably right as the actual (old) O ring has seen better days !! I had ordered an Oring for the carb but the one I received doesn’t fit so I decided to leave the old one... and it leaked air..
I’ll get the right one and fix this at some point