does anyone know the o ring size of the low speed idle theres one small o ring that holds the setting

why not just take the needle valve to the hobby store
maybe some other brand o ring will fit .also call sig or
e mail justengines in the UK Paul Landels there is the
guru on this one.other thought maybe glo powered rc
car engines any shops near you well stocked on parts
you are not likely to find in hardware store o ring box
but worth a try

thanks will give it a try

As mentioned I have gotten several of these from Paul at Just Engines. Lots of them made for other purposes will not stand up to the fuel/oil

I used an oring that was for the saito idle needle. The stock one was much to loose , didn't hold a setting and leaked air. The Saito ring fits very snugly in there and holds very well.

That's good to know, what size engine needle valve o-ring did you use.

My Irvine's seem to fit OK. Some of them seem to get soft and mushy though and like you say won't hold a setting.

ironcross,
I tried finding a part number. The o ring came from the Saito .72's idle needle.
They list many carb rebuild sets but i didn't see one for the 72's carb. They look just like the ones used in the 60 sized YS's. Unfortunately i don't have one for comparison.