So the last 24 hours of scootering have gone like this:
, you're thinking, that's a lot of up n' down for 24 hours
, and you're correct, so lemme fill in the details.
Yesterday, I took the VBB out to get some miles on it, thrash it around a little, and just enjoy riding. I had covered probably 20 miles, most of it on two-lane roads where I couldn't see another vehicle in the area northwest of me, which is pretty mountainous, so not much out there. Great riding. I should do it more.
I was heading back toward the house, doing about 55, when I hear a sudden grinding and the motor loses compression. Not like a seize, other than the part where the motor dies and won't start, but something mechanical. A sound I feel I've become all-too-accustomed to.
At the time it happened, my CHT had just broken 300f for the first time all day. I'd been pushing it 55-65. I was at WOT, but not full speed, so it wasn't the typical "roll off WOT and seize," either.
So I push the scooter down where there's a store with a parking lot I can leave it in, probably half a mile or more, then get an Uber home, get the car, get the scooter, bring it back, pull the head and...don't see anything that looks like evidence of a seize.
By this point, I'm too worn out to contemplate pulling the cylinder to find out what happened, so I decided I would let it go until today, and that in the meantime I would deal with the idle issues on the GL.
So I pull the reed block and discover two things. First was that the existing reeds looked fine. Second was that the replacement reeds were the wrong size, so I put it all back together and decided to see if it was still misbehaving.
Kick it over a few times and it fires, stumbles, will rev just fine, but still nothing on the low end. Then, it seems to clear up a little, but idling too slowing to keep running, so I rev it a little and turn in the idle screw a little bit, at which point it runs away and starts dieseling, RPM's right past 10k and then the motor died and seemed to have lost compression.
At that point, I just said, Fuck it, and went back into the house.
This morning, rejuvenated and expecting the worst, I pulled the cylinder off the VBB and found that it was fine. The piston was also mostly fine, but a tiny bit of metal. Swarf? a piece of aluminum can sucked into the intake? Something summoned by one of you with a voodoo doll for some perceived slight?
Whatever it was, it was smeared across the rings and had killed compression. Refusing to be denied my rightful Father's Day scootering, I got the rings off the piston, cleaned up the ring channels and the piston a little bit, put it all back together and am back up n' running.
The spark plug was looking paler than it should have, and the piston wash wasn't all the way to the ports, so I upped the main from 122 to 128 (so current stack: 120AC-BE4-128MJ) and it's running great again. It has a little bit of a rattle from something at idle, but it had that when I first built it, then it went away, so I'll see if it goes away again.
There's also something loose that rattles inside the exhaust that I can't get out, so it might be that. Oh, well.
I still haven't dug into the GL, but I'll get to it. For now, I'm going to chill out a bit and then maybe take the VBB out for another hopefully-not-ill-fated ride.
How it started. A nice ride out in the country.
How it went.
(A VBB fits in the back of a Tesla for future reference btw)
Swarf? Beer can? Voodoo curse? Who knows.