Rebuilding / Repacking a Vittorazi Atom80 PPG Exhaust 

LOL. I know what you mean. This video is boring enough as it is. No need to add music that’s painful to the ears too. Hopefully you found it useful and it saved you time on the ground so that you could spend more time in the air. 🪂🪂

Thanks for the kind words Thad. Keep in mind that I made this video a long time before Vittorazi came out with a service manual. This technique though has served me well. When I made this video, I asked Vittorazi how to wrap the packing and which way the inner mesh was oriented. They sent me the picture with the description of the orientation being “towards the final chrome”. So I put it in as per the video. But their maintenance manual, starting on page 36, shows it the opposite. 🤷🏼‍♂️ vittorazi.com/manuali/Maintenance_manual_Atom80_Eng_022.pdf?fbclid=IwAR3Q-giff3-l5xb9oVDGjdLas3HvJzciFITj2-omuz2YC-93aW-U9LPxfHM Personally, I like having the extra packing towards the baffle because there tends to be a lot of heat concentrating in that area and burning the silicone causing a heat signature on the outside of the exhaust. Also, one technique that I have used since this video is to use an old exhaust bracket (or make one out of flat stock) to secure the exhaust in a vice. Don’t put the vice to any parts of the exhaust that will be used during flight. But holding it in a vice will make it much easier to disassemble.

The high temp rtv worked great. However, it took a lot of heat (with a heat gun) to break down the rtv when I repacked the exhaust the second time. Still worth using it though. Just know that it’ll take a bit of effort to separate the exhaust the next time. I used an old exhaust bracket to secure the silencer in a vice while I heated it up with the heat gun and pulled on the pipe. I thought that it was going to catch fire because the silicone was literally melting and cooking inside before it would let go. 😂

210 hours on the engine and exhaust. Motul 710 @ 50:1 for all 210 hours. But I’m switching to Amsoil dominator. After doing a top end on a friends top80, I couldn’t believe how much cleaner, and better lubed his head, piston, cylinder & bearings were.

@@wednesdaykartingflyingclub8164 Interesting information. I have been reading up on Amsoil oils and read that they burn cleaner with lesser deposits, and wondered how the Atom 80 piston would hold up seeing as it only has one piston ring. Also interesting that you stayed at 50:1 instead of going to 66:1 after break in. I wondered if the engine could handle the richer oil mixture for extended periods of time and not load up with deposits. What octane rating fuel did you use? Was it ethanol free fuel? I've read up on Amsoil Saber Professional also. Is that you on RCU (Propworn)? I see a thread there from 2014 on Dominator vs. Saber.

@@mikehawkins3263 it was recommended to run the Motul 800 @ 66:1 & Motul710 @ 50:1. I’m not an oil expert, but after seeing my friends results, it was a no brainer for me. Plus, I had just done a top end on mine, so it was the right time to switch. We both run pump gas 91 octane. I sent you a Facebook friend request. I can send you pics on fb messenger. Let me know if your interested.

@@wednesdaykartingflyingclub8164 Yes, definitely interested. Thank you.

@@wednesdaykartingflyingclub8164 Thats the oil I wanted to try but Ill use this gallon of motul 800 first. My buddy uses the Dominator at 45:1 and loves it!!Let me know how the Dominator works in this engine.

I rebuilt this one at 213 hours. No real problems, I was getting oil leaking out of the rivets, so I wanted to inspect it.

I used a titanium bit that came in a set from Harbor Freight. Those rivets are stainless steel so they’re pretty thought to drill out and require a heavy duty rivet gun to replace.

Do you by chance remember what size drill bit you used to drill out the rivets?

@@white7684 the shank of the rivets are 3/16”. So that would be a good drill bit size to start with. Also, using a punch to drive out the pin in the center of the rivet (the mandrel) after drilling the head a bit, will sometimes be enough to break the rivet loose.

Thank you so much for the information. Just ordered all the parts that are needed to re pack the exhaust from sky sports.

@@white7684 perfect. SkySportsUSA are the best. Best of luck with the repacking. You can always call them for help too.

Yeah, not terrible though. I was surprised that the packing was still holding together quite well. Other 2 stroke exhausts that I’ve taken apart have had the packing shredding and blowing out the tip at times. There was a bit of oil in it, but not completely soaked.