Putting my Central Pneumatic(Harbor Freight 90234) back together and I am perplexed about how tight the check valve is supposed to be. Upon starting to thread it in it goes smoothly, but when it is slightly snug I can use an open ended or adjustable wrench. I can turn it a bit more but it gets to the tightest point that it wont line up in the proper position for the copper tubes. Just how much am I suppose to lean on this thing. I am afraid to destroy the treading on either the valve stem or the tank hole.

Hello all! I've been looking through the forum for answers and have seen alot of info but not what i haven't tried yet so far. Details: Engine is a LIFAN 188-bq 13.0 with electronic ignition. It's a horizontal shaft motor on a rather large commercial hydaulic driven tiller. First one of these I've worked on, what a beast! It likes to RIP the cord out right out of your hand like an angry gorilla and the owner is afraid to use it himself or allow others as well. I can vouch for that with the welt it left me on my gut! First thing i checked the key way to see if it had sheared, i mistakenly thought that HAD to be the problem but it was clean and tight with not a nail on it at all. Don't think the motor is very old but not really sure. Now the only other thing that I'm personally used to to predict this action is not having a blade on a mower or some kind of rotating mass to carry the stroke through its motion to start the engine. This however has a hydaulic pump on the output shaft and how much resistance it has on startup with tine control and forward control off is a mystery to me! What am i missing? Someone suggested maybe carbon build up but wouldn't it need to be at running temp for that to be true? This snaps back when it's cold and while it's hot, but otherwise runs fine! Any help would be greatly appreciated!