Ring and piston replacement fail: PLEASE HELP

[Bigtex]

Alright before I start I’d like to say that I am an amateur at working with engines. I probably made a really stupid mistake when going through this process that caused the issue I’m having. I just need help with identifying that mistake so that I can fix it.

WHAT I DID: because my 1984 200es started smoking pretty bad I decided that I would test my blossoming mechanical skills by replacing the rings and piston. I bought what I have verified to be the correct kit that contained the parts as well as the necessary seals for the engine. I followed the instruction of several YouTube videos and forums to complete the process. To the best of my knowledge, I did everything properly. Including, but not limited to, staggering rings, proper piston positioning, proper torque specs, re-timing, etc. There isn’t anything that I can think back to that I did wrong. I got the engine back on the bike and re-timed it. I also went ahead and changed the oil and spark plug. Once I got it started, I noticed the problem.

THE PROBLEM: upon starting the engine, I noticed that there was a good bit of smoke coming from the crank case vent. Something that I hadn’t seen before. I opened the oil fill cap and the exhaust was coming out through there! The oil cap was acting like the tailpipe. There was also a sizable oil leak from the seal between the cylinder and the crank case but only while the engine was running. The engine was running fine by the way.

THE QUESTION: I obviously have messed something up really bad along the way. I’m not sure what I did. So any thoughts or ideas on what I did wrong would be greatly appreciated. Thanks!

[yaegerb]

Did you get the cylinder bored? When putting the gaskets back on did you clean the surfaces to the point you could eat off them? After prepping the surfaces did you use 3 bond or 1211 bond on the cylinder gasket?

[Bigtex]

I did not get the cylinder bored. It seemed pretty clean so I didn’t do that. I cleaned off the surfaces pretty well but not eat off them well I suppose. And I did not use any bond. Didn’t know that was a thing. You think that did it?

[yaegerb]

I can guarantee your bore is out of round. Cylinders should be bored or at the very least, honed if you can measure that the round is still within specification. You will need to take the cylinder off and get it bored to the next size piston. I recommend going out to the la sleeve website, print off and fill out a 4 stroke order form. Check the box for a next size bore and have them provide a piston kit (there are options to choose from on the form). Send the cylinder and order form to them and you should have a freshly bored cylinder and new piston back in 3-4 weeks. When you get the cylinder back wash it with warm water and dawn dish soap, especially inside the bore. Blow it dry with compressed air and wipe down the bore with wd-40. Unfortunately your current piston is useless.

As far as sealing surfaces I would use 1211 which can be obtained through amazon. It will fill in the unrecognizable voids on the metal surfaces.

[knappyfeet]

Wish I could like this twice.

LA Sleeve are my best friends ever!

[jb2wheels]

The bore is likely the issue.

Are the rings in upside-down?