This is a question for all you "old time" YS users..... First a little background.

I have a 120NC that has not seen much run time. Bought used but according to the son of the PO about two tanks of fuel through it. I would say that is correct as there was no staining of the exhaust valve. At this point there is less than a half gallon of fuel through it.

My problem is I can get a good idle or a good midrange/transition but not both at the same time. I'm aware that this engine series has a history of a rich idle and there are some fixes that are more or less permanent as if you screw up you are buying new parts.

So to my question. Does the 120NC share size wise a throttle butterfly with another YS engine that has an idle mixture screw in the butterfly?

Thank you!

Ken

I would try calling Central Hobbies. They may be able to help you out.

Should be a hole in butterfly. Drill it out slightly

All YS parts for all engines are still available from YS Japan Directly

Sent the engine to Richard at YS parts and service. He replaced all the gaskets. Said there was no gasket under the carb and suspected an air leak. All gaskets replaced and he drilled the throttle butterfly to .072". He said it ran great now. Our season is all but done though we may have a few good days. If I have time I mount it back up and give it a go. Work is crazy busy now......

Ken