A 20-year orphan

[Grimly]

First time start for the '79 GS850 - honestly, no BS, I hadn't done a trial run before the camera was on. This was a genuine start for the first time in 20 years. Using the diy ignitor and the Stromberg carb, which has a knackered diaphragm, and likely a sticky piston, I think.
I just had to crank it to see if it caught with fresh fuel and sparks, being a bit impatient.

https://www.youtube.com/watch?v=wpt1nzdKr9A&feature=youtu.be

I'll be stripping that Stromberg off and replacing it with a temporary 44mm SU that I know worked ok on the other bike; if not perfect, at least I know where I am with that - then it will be replaced with another 38mm SU, same as the other one.
Apart from that, I must replace the manifold O-rings, as a matter of course, so it has to come apart.
Hearteningly, all exhaust pipes were reaching the same temp after a few starts, so that's a slight relief. I'll warm it up again and check compressions.

[Grimly]

Assbiscuits and robbery - looks like a knackered crank bearing on #1 cylinder. I'll pull plugs and determine exactly what pot it is, but the blowing exhaust was masking the sound of the clunk and when that was quietened down the rattle became more obvious.
I've read all the threads about the starter clutch and the clutch hub nut, and I'd be surprised if it's either of those. Blowerbike hit it on the head, I think, when he listened to another one and said it's more serious than that.
I was living in hope (and a bit of denial) because I already knew these engines sound terminal with a bad cyl head exhaust blow, but this is more

[chuck hahn]

Crap. That just sucks in so many ways....But youll sort it well .

[Grimly]

Well, I've got another crank which needs closely looked at - it might be serviceable; it's the pita stripping and the cost of another gasket and o-ring set. Oh hang on, I've got an o-ring set, just lack base and top end gaskets. Bit of a sod though; I'd planned to pull the jugs on the '80 for a top-end refresh during the winter and was keeping them for that.

[chuck hahn]

How do you sync that Stromberg???

[Grimly]

Internally, it's mixture is controlled by a tool which goes down the central diaphragm holder and that raises/lowers the needle in the jet. Similar in principle to the Keihien, but no need to remove dashtops and dampers, just unscrew the top cap and lower the tool down. Set it up for idle mixture and the right needle will do the whole range - a black art and much more info is available on SU variations than Strombergs, which is why this one will be getting another SU eventually; although it ran quite well, there is a really limited range of options compared to what there used to be (and even then, there wasn't much). There's no messing around with pilot, mid, main seperate settings.
I always found the mixture distribution with this manifold and carb to be quite good and didn't take much fiddling with at all.
I just used what was available easily at the time - SU would have been my first choice, but the Stromberg came with the manifold and I just decided to use it as it was there already.
The diaphragms (decent ones) last for several years and are dirt-cheap, so no biggie.