1980s Murc - bottom cylinders not firing

[mattoc]

I have a 1980s 50hp blueband murc and for some unknown reason its not firing on the bottom two cylinders, there is plenty of spark, and the carburetor has been rebuilt and is working as it should be, but when I remove the bottom two leads there is no change in the motor which is running really ruff, any ideas would be a great help

 

[Laddies]

Re: 1980s Murc - bottom cylinders not firing

If the engine will pick up the cyls once you are above idle it's probable a bad reed or in some cases a bad lower main seals

 

[mattoc]

Re: 1980s Murc - bottom cylinders not firing

what are reeds?

 

[Laddies]

Re: 1980s Murc - bottom cylinders not firing

Reeds are petal type valves that control the flow of fuel air mixture at idle and help the engine to develop vacume to start and idle. they are inside the crankcase and the engine would have to be split

 

[mattoc]

Re: 1980s Murc - bottom cylinders not firing

what is the simplest way to test compreshion