Cub no-start

[TSWolf]

I have a Cub I picked up at auction recently, not running. It gets good blue spark, and spark timing is good. It has good compression. At one point, I did have it running. Now, it will not start, still have good compression and spark. That leads me to believe it is a fuel issue. Even when I spray carb cleaner into the carb, it won't run. I am out of ideas. Any help is greatly appreciated.

 

[gene bender]

Idle circut mite be at fault cause that circut does need to work good for starting

 

[golfcartman]

Try starting fluid( eather) and it should at least hit and try to start. I never could get much out of carb. Cleaner. If it doesn't start with that then
you have a timing or compression problem. Is it magneto or distributor? How much compression does each cylinder have?

 

[jeffcat]

Both types of carbs are a snap to rebuild with a little time. You want to stay away from start fluid and use a pump can with a little gasoline in it. Start fluid can raise all kinds of havoc on these engines. Was just covered a week or two ago. Neighbor blew a hole through an aluminum piston. I use a little fresh Hi-test in the pump can. Both are up draft carbs and I would also replace the manifold to carb gasket. I hand cut the one on mine cause I have the newer Bendix/holley carb. Has a smaller hole to gasket pattern. You need to make the larger one to match things up. Twin floats in mine. The older IH carb has one float. When you adjust the float to be perfectly level with the top half of the carb, NEVER push it down with your finger. You just busted the needle float valve. Use a tiny pair of plyers. Good luck! Photos are of my carb. get back to us.

 

[old]

I had one this year that had good spark as in a blue/white but after checking things a bit more found that when #1 was hitting the piston was not at TDC but at the bottom of the cylinder instead of TDC I would check that to be 100% sure

 

[khouse6]

i had an engine that would not hit, even on ether. i tried lots of things; finally emptied gas tank and it ran. i believe that something within the
gas was a problem, maybe water. ? ? ? ? ?

 

[Dieselrider]

How cold is it where you are? If it is cold, those updraft carbs can form a bit of a bubble right above the carb not allowing the mixture up into the intake. Hold a hair dryer on it for a few minutes (3-5) to warm it up and then try to start. Just a thought, YMMV.