Hard startin

[Goman]

I noticed a couple of guys on you tube starting Johnson K45’s like mine and they were not pulling nearly as hard as I’ve been. So i took a cylinder off that I remembered having trouble putting on. It’s hard to tell by the picture but the bottom of the piston skirt is shiny from rubbing. The piston measured around 3 thousands out of round but it was kinda hard to measure while it was still connected. I believe the rod is bent. I know there are ways they fix them in the manuals. I was thinking about trying to take the studs out of the crankcase and see how the cylinder lines up but I wanted to run it by you guys first.
Thanks for the help
Glen

[Tubs]

Click on the link and scrool down to Tom Manley’s
system for checking and correcting rod alignment.
https://aomci.org/forum/viewtopic.php?f=22&t=10070

A "Boat House Repair" is one that done without having tools or the skills to do it properly.

[Goman]

I had to back the cylinder back off the studs a bit to get any kind of leverage. I believe I got the top and bottom gaps even. It seems to turn a bit easier but I’m still not convinced. I’m going to put the rings back on and mark the skirt to see if it’s still rubbing any. I guess I could take some of this scrap would laying around and make me a cradle for piston work next time 🙂

[Tom]

Two possibilities… Are the ring end gaps correct? You would have to take the rings off to check this. Also, is there a lot of carbon in the ring grooves keeping the rings from going all the way in like the are supposed to?

I just finished up a K-45 rebuild, and those rings were not easy to get off. I used strips of an aluminum can, slid under the rings, to get them off without breaking them.

Tom

[Goman]

The rings seem fine. I believe I bent the rod while taking the pistons off to clean them. Unless the rod was already bent. Is there much of a way a rod can bend while running the motor?

[Tom]

The most common way to bend rods is to unbolt the jugs, and accidentally bump the jugs downward before taking them off of the pistons. The bronze rods are quite easy to bend. While running?.. very unlikely.

There are a couple of different ways the rods can be bent. Side to side won’t show up, since that’s the same orientation as the flex in the wrist pin. Up and down will show up just as you see in the photo you attached. If the shiny spot is evenly front and back, the bend was likely just up and down. If the rod is twisted, all bets are off, and you’ll need a jig to bring the rod back into alignment. The jig I’ve seen has two parallel rods, one goes through the big end, the other through the wrist pin end.

Tom

[Goman]

If these rods are easy to bend they’re sure not easy to bend back. I’ve had the cylinder all the way off the studs the piston all the way extended and put a lot of weight on the cylinder and smacked it with a rubber mallet… increasingly several times. The last time I managed to get the line drawn on the piston to move a little more towards the top as shown in the picture. There is bound to be something else going on with it I can’t figure it out. I have another crankcase and rods for this motor that’ll I’ll probably end up trying to use. But I believe I’ll take off tomorrow and just see if I can’t get it to rub on the other side 😀

[Author]

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