No, it turns out I owe Trevor an apology, there's only one vacuum spigot, and that's on the left carb. (closest to the petcock) When I got the bike it didn't have a fuel tank, and the petcock I bought for a T350 isn't a vacuum style petcock, but looking at some pics on the interwebs tonight I saw that the 1969 T350 has a vacuum operated petcock.
No biggie, I prefer non-vacuum petcocks anyway, so I put a piece of vacuum hose on the spigot and blocked it with a screw. I suppose I could drill and tap the other carb's body for a screw in spigot, or replace the right hand carb with my spare left hand side carb with it's spigot and then I could use the vacuum gauges, but I'm not that fussed. I am learning more and more about Suzuki T350's every day though.........
The weather is still miserable, it's cold and wet, but I bravely braved the arctic conditions to bench sync the carbs this afternoon. Now I thought about this a lot whilst "working from home" today, and decided that I'd just sync the slides with them sitting completely closed, because all I really needed to do was to make sure that they had the same amount of slack in the cable, at the adjuster. I attached the throttle assembly to the cable to remove any additional slack, then just wound the cable adjusters on top of the slides out until there was 1mm of slack on both sides. When I've got everything else set up and it's ready to fire up for the first time I'll use the idle adjusters to lift the slides, and then sync them again.
A little bit of dicking around I suppose, but no biggie, I remember "bench syncing" some CB750K0 carbs once, using a piece of wire, but once I fired it up I realised that I'd effectively set the idle too high, so I had to do pretty much what I did tonight, drop them all the way down again, and just make sure all the cables had the same amount of slack, lock them in, fire it up, adjust the idle with the 4 idle screws, then sync them again, this time using vacuum gauges.
Anyhoo, I did finally mount the carbs and I hope I've correctly routed the throttle cables through the frame, I think I have and the slides snap back when I release the throttle, regardless of where I turn the handlebars. I had to also connect the choke linkage rod, which is a pretty basic piece of wire bent at right angles at each end with a hole for a tiny split pin. As you'd expect, I had every split pin imaginable, but nothing small enough to fit thru the hole, so I did some red necking. The split pin in the pic is 1.6mm thick, but too thick for the holes, so I modified them.
T350 Tuesday 8 Jun 2021 by
Terry Prendergast, on Flickr
And they did the job.
T350 Tuesday 8 Jun 2021 2 by
Terry Prendergast, on Flickr
By this time it was dark, cold, and I'd decided that 3 hours was enough time spent. I did attempt to find some pods (as I'm waiting on the rubber air box adapter) but I had no luck. The pods on my Mikuni 33mm smoothbore carbs for my Z1-B were too big, and the old K&N's for CB750 carbs were too small. Oh well, I won't be operating it in dusty conditions any time soon, so hopefully the rubber thingie will arrive before I take it for it's first shakeout ride. I'll be hooking up the oil pump cable and adjusting it, then installing the wiring harness, battery box and battery tomorrow, and with luck I'll be able to kick it over and see if I have spark, it'd be nice to fire it up this weekend, but I do have to do some more problem solving to do before I can do that, as I'm missing a key part, and don't have a replacement coming as yet. More tomorrow.
T350 Tuesday 8 Jun 2021 1 by
Terry Prendergast, on Flickr