I’m new to karting and have about 2.5 hours on my top end. My engine builder kept saying to push for a 1300 egt, even though what I read here was that 1200 was HIGH. I was running ~1100-1200, usually a 165 main jet with a 269 emulsion tube. Just took the top end apart to check how it was running. Looks like it was not good… 
Is this just the result of being too lean? Or potentially a timing issue? I was running VP98L with 5% ELF 909 oil.
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Looks like something went through the engine and bounced around. How is the clylinder?
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Ring pin? (characters)
It looks like part of the piston broke off and bounced around inside the engine. Other than the top of the cylinder the walls seem ok. I can just barely feel a groove on wall near the intake. But my last lap it was pulling record speed so none of this seems to be hurting performance. I can probably just do a new piston and combustion chamber to be safe. Curious what caused this to avoid it in the future though…
Looks fine to me. The ring was in place when I took the cylinder off.
Well, I just figured I’d change the transmission fluid while waiting on parts. The motor mount was installed by the engine builder. It didn’t budge with an impact! I went to my breaker bar and the bolt heads stripped out. Pretty pissed that I spent $8,200 on this and was advised to lean it out to the point the top end is destroyed and the motor mount was installed in a way that’s unremovable. I’m just going to ship it back to the engine builder at this point and let them handle it. 
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Not a jetting issue. There’s definitely debris that has implanted in the head…I see the material that is missing from the piston, but would also inspect everything upstream (intake/reeds/airbox) to make sure there aren’t any other issues.
That type of snag on the intake side isn’t something I see on TM’s, and all of my engines run similar fuel and oil. Something else is going on for a piston to let go with that little time.
1,300 EGT is on the high end for an R2, but it’s also going to depend on your engine, pipe, and sensor. I’d start closer to 1,200 and work your way up from there.
Also I use a large 1/2” drive ratchet when tightening the engine mount bolts, so an impact doesn’t always knock them loose in my experience.
What!? Are these some big ass M12 bolts? I only ever nip up the QTY4 bolts on my TAG engines with my standard 3/8 drive.
Do shifters tend to rattle the fasteners loose?
I checked the reeds and one had a small chip in the corner. Probably about 1/2 a mm by 1/2 a mm missing. I did recently switch air boxes and after switching, I tried to kill the engine on the stand by covering the intake holes and it just kept running. When I took the air box off their was some dirt (nothing large at all) around the carb on the inside. Seemed like there was a leak somewhere but everything was tight. Maybe something got in that way…
I guess that also makes sense because the session this happened in, my max egt was 1120.
Just to be clear, is the pin still in place - it wasn’t clear on the photo above? And part of the piston edge is missing immediately above the pin hole/gap. I ask because a similar thing happened to me on a CR125; cost me a head and cylinder.
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I suppose more consequential than the drive size is fact that the ratchet is longer than standard. It just allows me to have more control vs tightening with a smaller 3/8” drive ratchet. Vibration on most shifters isn’t what I’d call crazy high, but getting to those bolts isn’t as easy as your standard nut/bolt on chassis parts, so I don’t want to worry about them coming loose. No different than any engine mount really…it’s rare that you see someone’s engine mount come loose, but it certainly happens from time to time. Rotax vibrations are about the same intensity as my electric toothbrush 
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