Oil is cheap. Oil change is fun. I change my oil after 300 miles of Red line, valve bouncing, full throttle, back wheeling, lap time cutting, thrashing ! 🤣

 

right, cylinder walls

 

I figured out where the sand in the airbox originated.
I believe the voltage regulator rectifier in the motorcycle was aftermarket. I noticed it was opening up and sure enough was spilling sand all into the airbox. I didn't mention before that the regulator rectifier was in the airbox as well. Regardless, I've ordered a new one and will be replacing it.
I used compressed air + a vacuum to clear out as much of the sand as I could from the engine. Given how easily it was crushable with the spoon, I'm not gonna worry too much about what I wasn't able to get.
I am going to do a cleaning of the throttle body, replace regulator rectifier, do an oil change, and I think I should be in good shape. What a pain in the ass lol but at least I think I'm close to being done with this concern.

 

 

"I didn't mention before that the regulator rectifier was in the airbox as well."
Huh? You'd been fiddling with the R/R and happened to place it in the airbox? That comes across as a strange way to heatsink or otherwise isolate the internals of the R/R. But I plead ignorance. In any event, congrats for finding the source of the "sand".

 

The R/R was in the airbox when I first opened it up to inspect it. Idk, I assumed that was normal.
I don’t think I’m gonna keep it in there when I replace it - just gonna have to find a good location for it elsewhere

 

This was a common fix on the 600/750. Overheating R/R burning out. People moved them to the left side faring and into the airbox. The OEM R/R was replaced with a revised version around 08. Which fixed this problem.
When I read of this, I didn't think anyone would mount it on the inside ( clean side ) of the airbox.
WARNING To others !

 

Only February and I think we have the "most fucked up mod" award winner for 2022.

 

"The R/R was in the airbox when I first opened it up to inspect it."
So there's a hole in the side of the airbox for the wiring bundle to the R/R? If so, you may need a new airbox.

+1000 on most fucked up mod. Sounds like something by Shervin. Second only to putting NOS energy drink in the tank.

"common fix on the 600/750...moved them to the left side faring and into the airbox"
No problem with left side fairing but inside the airbox? Will I find this "fix" mentioned elsewhere here if I search? I'm afraid to try as it might put me into seizure.

 

Glad you found the problem. I never would have guessed that, and I've never heard of anyone mounting the R/R in the airbox.

 

So, the "Sand" inside the R/R is there for cooling, as a heat sink. Or flame proof, for fire retardant ?
Or both.

 

Another theory I’ve heard of is they put sand in there to weigh it down - make it seem like it’s higher quality cuz it’s heavier lol

 

The SCRs get hot and need to be cooled, which is what the finned heat sink is about. I'd expect there to be conduction paths on the underside of his circuit board. Sand is a poor heat conductor. It might be there to keep heat away from the black tar that seals things. Seems like a dumb/el-cheapo idea.

 

Sand is probably a just a heat conductor that dried out.