Old Piston + New Rings = Too Tight
 

I have an interesting conundrum that I am hoping that other 2 cycle gurus might be able to help with. Note that my issue is actually with an 80's era Columbia but the Columbia forum doesn't get much traffic. Being that Columbia and EZ Go 2 strokes were very similar carts I am soliciting input here as well.

I recently installed some new rings on an original piston. At .015, ring gap was spot on out of the box. That said, the rings somewhat looked too big in that they seemed to be protruding father out from the piston grooves than I am accustomed to (see pic). As well, when I placed the piston / rings in the cylinder it felt tighter than normal. Still, I got everything seated in the cart only to find out that the starter won't turn the motor. Yes, I had the cylinder nice and lubed up. To confirm that it was, in fact, the cylinder that was the problem, I took it off completely then tried to turn the motor. The motor turned over like a champ without the cylinder on it so the bottom end is fine.

Has anyone ever encountered something like this before? I did some online research and the most promising information I have found to date is that there can be a "conflict" between new rings and old pistons. They should either both be old or both be new. I have ordered a new piston / rings to try this theory out but wanted to pose this to the group as well.

Thanks for any input in advance.

Re: Old Piston + New Rings = Too Tight
 

You did align the rings with the pegs in piston and not around them ? The former owner of Suzi did that with a similar result

Re: Old Piston + New Rings = Too Tight
 

I should have added that part. For sure, the rings "notches" were aligned with those "groove posts" whatever they are called. This included several "double checks" during the troubleshooting process.

Re: Old Piston + New Rings = Too Tight
 

Did you put the rings bevel side up?

Re: Old Piston + New Rings = Too Tight
 

That's an awesome thought but on this cart the rings are bidirectional. No bevels.

Re: Old Piston + New Rings = Too Tight
 

Just about every 2smoke engine I’ve built the rings stick out like that when the piston is removed. That looks normal to me.

What’s not normal, however, is the rings binding when installed in the cylinder. You were able to install the piston in the cylinder by hand? I would have thought if it was the rings causing the binding you would have had a hell of a time trying to put the cylinder on to begin with. Not just “tighter than normal” that won’t lock up an engine…

What I would suspect more likely is the head clearance. Have you checked the squish clearance between the piston and the head? I’ve got a hunch the piston is hitting the head and binding there… maybe install the cylinder and leave off the head and try and see if it will spin by hand

Re: Old Piston + New Rings = Too Tight
 

Did you clean out the ring grooves in the piston? I use a peice of an old ring to clean out all the carbon deposit before fitting new rings. If you gapped the rings correctly, it can only be the piston pushing the rings too far out in the bore. If not carbon deposits, then the ring grooves are not deep enough for the new rings.

Re: Old Piston + New Rings = Too Tight
 

Only other thing I could think of is maybe they’re the wrong rings?

Re: Old Piston + New Rings = Too Tight
 

Is the starter generator locked up?

Re: Old Piston + New Rings = Too Tight
 

Something needs to be locked up!!!!!