Why replace both the piston and rings ???

Fri Sep 10, 2004 4:36 pm

I am in the process of unsticking a stuck Cub engine and will soon have the pistons out so I am starting the hunt for parts, a lot of dealers only seem to carry piston/ring kits and I am wondering why? Is there a general rule with Cub engines on replacing pistons? I don't know piston or cylinder condition yet so I may end up buying a full kit anyway, the engine stuck with all pistons aligned at mid-stroke, I can see the top half of the cylinder and they don't look bad at all, 1 & 4 are clean with no ridge, 2 & 3 have carbon, a little rust, and no ridge. I have some pictures I'd like to post but I use SBC-Yahoo for my ISP and it may not work, what are the steps to post and I'll give it a try anyway.

Thanks, Glenn

Fri Sep 10, 2004 4:47 pm

I don't believe you can post directly from Yahoo / Geo Cities. You will have to use another photo host such as Picturetrail, fotki,hp Photo or similar site. If you would like, e-mail your pictures to me and I will upload them for you.

Fri Sep 10, 2004 6:40 pm

:) Thanks for the offer Bigdog, but I thought I better try to learn the process so I signed up for picturetrail, and here's my first attempt.


Fri Sep 10, 2004 6:49 pm

:roll: Well, that didn't go so good, lets try it again.

Fri Sep 10, 2004 6:52 pm

:oops: Same deal, attempt #3.


And just like that we have a picture of the really, really stuck 1948. G2

Fri Sep 10, 2004 7:05 pm

1956 model, also stuck




Fri Sep 10, 2004 7:14 pm

Based on the amount of crud, they don't look that bad. If they clean up without getting too oversized, you should be able to rering the existing pistons.

Of course, I am sure most observers of the first picture immediately zoomed in on the lower left corner of the picture.

Fri Sep 10, 2004 7:22 pm

Jim, are you referring to those high-crop wheels?

Fri Sep 10, 2004 7:47 pm

I was actually looking at the PTO adapter.

Fri Sep 10, 2004 7:48 pm

Some things come to mind. Some of the valves on the rusted cylinders are closed so that lessens the chance of rain in the exhaust.
1 what was the condition of the cylinder head gasket at the two rust cylinders? Perhaps it was a leaky gasket that caused the rust.
2 Does the crank shaft move at all in either direction? How bad is it stuck
3 Was there oil in the crankcase? Does the oil have metalic flakes in it? Does it look brand new? Is there water in the oil? Some one ran it out of oil or the oil was contaminated and seized the bearings.
Lots of luck. I hope it is #1. I would find that the easiest to fix. I think kerosene with 0000 steel wool will clean the rust and not oversize the cylinders. From the lack of ridge you mention I would wonder if some PO did an overhaul screwed up the gasket and gave up.

Sat Sep 11, 2004 8:37 am

I've done 2 Cub engines so far and only needed to swap the rings out. The pistons were fine. The valves don't look too bad at all from here.

Jim Becker, why would you say a lot of folks would be drooling over the PTO adapter? Are they a fairly rare item? I have one on my '49 with a pulley on it, but no mower. My '67 does not have it complete, someone took it out previous.

Glenn, good luck, looks like a good one to me. I like the "rumble seat".

Sat Sep 11, 2004 8:55 am


That is not a regular belt pulley gear box. That is or what appears to me to be a Howard Gear Reduction Unit. They a sometimes on eBay at around $500.00US and higher. I think one unit went for almost $900.00US.

They are RARE :!:

Jim, am I correct? I spotted that right off. Nice unit. Wonder if it works?

Sat Sep 11, 2004 9:00 am

It isn't a Howard speed reducer, which slows the ground speed. It looks like a PTO speed reducer. Here is a thread from a while back that talked about them.


The PTO speed reducers are of fairly limited practical value. (How many readers of this actually have a piece of equipment that would use it? Few.) They are rare enough to be hard to find but common enough that most everybody knows what it is and wants one.

Sat Sep 11, 2004 9:30 am

"I was actually looking at the PTO adapter."

I don't think I am looking at the same picture you guys are looking at.....I don't see anything but the normal PTO shaft and plate. :oops: :roll:

What am I looking for :?: I must be missing something. :oops:

Sat Sep 11, 2004 9:35 am

When I first looked at it I also thought it was an adaptor, but after going back and taking a closer look, it appears that the angle of the picture and the different color is making a standard pto appear to be an adaptor.