HD25

[shane-r13]

Whats the easiest way to remove a piston from a Johnson HD25? I cant get this puppy to run and have gone through the ignition system and carb. It sat a long time and I suspect it has stuck rings. I have 65-70psi of compression and my other Johnson’s in this era seem happy and run with that psi but this guy just wont seem to fart at all. Anyways I’m tempted to remove the pistons and make sure the rings are free but would like to do it the least invasive way. I’m assuming tear the bottom end of the crank off and cylinder head and pop the pistons out the top?

Thanks for any input guys.

[frankr]

You can check for stuck rings by removing the carb/manifold from the side and give them a poke. But that probably isn’t the problem

[shane-r13]

quote FrankR:

You can check for stuck rings by removing the carb/manifold from the side and give them a poke. But that probably isn’t the problem

I’ll do that. Easier than tearing it apart for now. What do you think the issue may be then? I have spark and fuel. Mind you i don’t have a proper spark tester at the moment but when plugs are grounded to block i have spark. New plugs, points set and cleaned.
Thanks

[shane-r13]

quote FrankR:

You can check for stuck rings by removing the carb/manifold from the side and give them a poke. But that probably isn’t the problem

Just took carb housing manifold off. You were correct. Rings were good and loose…..now i’m really lost.

[bill-loveland]

Can you get it to pop with starting fluid? If you can, you’re not getting gas through the carb. If you can’t, you’re not getting spark.

Be sure to use a starting fluid with lubricants added.

[The Boat House]

quote Shane.R13:

I have spark and fuel

Bring one piston up to TDC and check that
the plug wire for that cylinder is going to
the coil that is going to the points that
have opened for that cylinder.

[garry-in-michigan]

Excessive main bearing ware can leak crankcase compression and cause hard starting and poor idling . . . 😎

[shane-r13]

Ok, So I swapped all the coils and condensers for a known good TD20 I have. Starts now but only starts and runs when the throttle is maxed out then dies after 20-30 seconds. I went and invested in an adjustable spark tester. With the old coils, it jumped a 1/4 gap but it was intermittent, thats why I swapped it all out. Now as Garry In Tampa stated I’m starting to think of a compression leak somewhere. Are the main bearings replaceable in this motor? I haven’t done a compression test in a few days and not since it ran a bit but before hand it had 65-70lbs.

[shane-r13]

SO Update, Got this motor running. Not great by any means. Now it overheats and my impeller is not pumping water. I’ve cleared all passages and just by looking it seems like the reciprocating pump is swelled visually. Any leads on one thats cheaper than the $40 usd one on ebay? Seems excessive for a motor that is not likely worth more than that. Also have noticed that my primer seals on the carb are gone and leaks fuel when the primer is plunged.

[frankr]

Club member Brian Wilcox makes the pump rotors

Call 810-794-7685 before 8 pm est please.Or email Baron0418@att.net. please note the b must be a capital.

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