Vittorazi Atom80 top end rebuild 

Thanks Will. Yeah, I was looking for Atom80 maintenance videos and pretty much found nothing. So that’s why I made them. They’re nothing special, but hopefully informative.

How many hours did you have on the Atom before you did the top end. Did you do compression test ?

@@shannonwhitaker9630 actually didn't do the 100hr. until 200hrs. I had the maintenance done so I'm not sure about the compression test. That being said, I don't think my motor is as powerful as it was when I first got it.

I was just curious how long these little high rev'in engines could be pushed before they needed rings or maybe just a whole new complete piston assembly. I think it's safe to say that most 2-cycles of this type are going to need this servicing somewhere between 2-300hrs. To keep peak power it really has to be done. My experience with smaller Rotax engines indicate that by 500hrs flying time both the top and bottom end will need a complete rebuild. Good job on your work and I hope you can post further updates on your experience with the Atom.

@@shannonwhitaker9630 I clean the piston & head every 50 hours. Install a new piston ring and bearing every 100 hours. Change the piston at 200 hours, and plan on doing a complete bottom end at 400 hours.

I’m still a novice at setting up shots. 😂 I missed a few here. Hopefully you still find it useful. Are you headed to Salton Sea for the fly in this year?

@@wednesdaykartingflyingclub8164 I’d love to but sadly I don’t think we will have the funds this year with everything else we want to do. On the schedule for next year for sure!

Glad to hear that your squish gap checked out. I haven’t seen anything posted about ring end gap measurements for the Atom80 anywhere. I’ve replaced several pistons, rings and a few Atom80 cylinders with parts straight from www.SkySportsUSA.net and haven’t had any issues. So I guess the tolerance on the ring gap must not be that critical. 🤷🏼‍♂️

@@wednesdaykartingflyingclub8164 Thats cool.I had a top 80 before this and they also had no ring end gap setting.They told me it was set from factory. Thanks for all the help man.I have a few heat cycles through her and she runs strong!!

The piston is not reversible. The skirt on the intake side is different than the exhaust side. There is an indexing pin in the slot that holds the ring. That pin is what keeps the ring from rotating around.

@@wednesdaykartingflyingclub8164 good info much appreciated!

I’ll do the best that I can to explain it. The Squish Gap is the measured distance between the top of the piston and the cylinder head at the outermost edge of the cylinder inside the combustion chamber. Setting this gap within the proper range is important for several reasons. Most importantly it prevents the piston from hitting the head (keep in mind that the connecting rod will stretch when it’s heated up and running at high rpms), and it also sets the correct compression (which prevents pre detonation). To measure this gap I removed the spark plug, took a piece of solder and bent it in a “J”, inserted the solder inside the spark plug hole (making sure to keep the solder touching the cylinder wall at all times) and slowly pulled the starter cord. You should feel slight resistance as the solder is “squished” by the piston. The key here is to use solder that just slightly oversized than the gap you’re looking for. Then you simply measure the solder where it’s squished (keeping in mind that there might be a larger measurement at the very tip of the solder due to the gap between the piston and cylinder) measure right next to that. I like to measure over the intake, exhaust, front & rear and take the average measurement. Edit. I forgot to mention that the way you adjust this by changing out the base gasket. Base gaskets are usually sold in sets. Each gasket in the set is a different thickness. Adjust the gap by removing the head and cylinder, measure the base gasket. If you need to decrease the squish gap, you do this by using a thinner base gasket. So you would just subtract the amount of thickness that you need to drop from the one that was in there and use the gasket in the set that puts you in that range. The opposite is also true. If you need to increase the gap, just add up whichever combination of gaskets would put you in that range. Hopefully that makes sense.

@@wednesdaykartingflyingclub8164 thanks for the response! What diameter solder did you use?

@@wileycoyotentaz for this application I believe that I used 1mm solder. Slightly larger might’ve been better though.

@@wednesdaykartingflyingclub8164 thank you! What is the target dimension were you aiming for?

@@wileycoyotentaz “Between 0.75mm and 0.95mm

LOL. I believe they do, but It’s only for obese Americans. 😂 In the US it requires a doctors prescription.