Mini Mac Carb Question

[Scottnc]

'73 Mini Mac 35. Unless the idle is set too high (IMO) or at least high enough the clutch has the chain spinning the engine will idle at most for 10 seconds before slowing and dying. And regardless of idle speed, the idle mixture screw has very little effect on idle quality, it does but not much. Just had this thing apart for seals, rings, carb kit, bar oiler problems, etc. but mainly because it was dying and not restarting and when it did run the carb adjustment required constant tweeking. . . thought maybe it had a crankcase leak. Anyway, all back in one piece, no smoking and the bar oiler finally works I just need to get a handle on getting it to idle better so the idle speed can be slowed. Is it normal on these saws for the engine to be numb to the idle mixture screw? It is almost like the high speed side is fueling at idle. While the carburetor was apart I chased the carburetor idle and high speed circuit around with brake clean, it seemed everything was open.

 

[heimannm]

What you are describing sounds like the check valve has failed, very common issue on the MDC carburetors and the parts are available.



Remove the welch plug (Item 14), the retainer (Item 12), and the check valve (Item 11). Check the Mini Mac Small McCulloch thread in the stickies for more details.



Mark

 

[Scottnc]

Thanks Mark! The only "kit" I could find was gaskets and diaphragm only so that check valve is quite likely the original to the saw.

 

[Scottnc]

I have read and read the MDC posts in the MM/small saw sticky but do not see mention on how to service the check valve. The welch plugs are out, the tiny circlip and screen are out. Does the brass sleeve or whatever it is come out? There is a spring loaded (I think) flexible rubbery-ish disk in there I assume to be the check valve? Need guidance before I wreck something made of unobtainium.

 

[gumneck]

I have read and read the MDC posts in the MM/small saw sticky but do not see mention on how to service the check valve. The welch plugs are out, the tiny circlip and screen are out. Does the brass sleeve or whatever it is come out? There is a spring loaded (I think) flexible rubbery-ish disk in there I assume to be the check valve? Need guidance before I wreck something made of unobtainium.

https://www.arboristsite.com/thread...mall-cc-chainsaws.218770/page-62#post-7658700What Mark said above and the thread I linked I have some recent pics of what I did on a minimac check valve post #1231.

 

[Scottnc]

Just what the doctor ordered, thanks. Me thinks the smart money is on waiting until the parts are in hand before proceeding. Speaking of parts, has a kit/supplier surfaced that sells a comprehensive kit with the correct parts? Seems missing and or incorrect parts is a common theme when it comes to MM carb kits. My gaskets and diaphragm are new and the welch plugs could be reused in a pinch - I should post a picture of the tip of the punch I ground, worked slick - the check valve is primarily what I need.