Kitty Cat Snowmobiles

I have a 1978 Kitty Kat. Sat for 15 years before I bought it. I have been able to get is started and running, however, when it idles, there is a continual Ping/knock in the engine. This only occurs during Idle, when it is throttled and running, it runs smoothly. Any advice on the potential problem?

You must have the old style recoil....The post on the recoil is going bad moving up and down inside the starter cup....yes it will break apart...what bad is also the end cap on the recoil chucks out and the starter pawls may come flying out....could hit someone.....I've seen that happen

So how do I fix it. Do I remove the recoil and adjust something or replace something? I am new to these older models and Cats in General. I own a few polaris models.

you need to replace the recoil.....the old style is still avaliable