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I've had my original DG for over 30 years. Yes the collector leaks, a bit. It's not a concern. Given the fact that 6 headers run into a single formed piece and everything aligns perfectly, I'd say the bit of "soot" you'll see is a tiny exception for the un-gasketed, dry fit. Sealant has never occurred to me because I'm more concerned about getting it apart and back together easily when I occasionally remove the system for general maintenance and cleaning. Don't "over-think" this! Your time can be spent in more productive ways.
......and yes, the sound is "something" else!

scotch

In the UK exhaust leaks will fail the annual MoT test.

Mine must leak but never so much that I've noticed it.
If the Govm't over there in the UK is concerned by exhaust leaks on motorcycles I think that the inspectors need better training.

Perhaps a real job!
Bill

I've taken her out again and did some more tuning work on the carbs. I have the air screws set at 4-1/2 turns and did a vacuum sync on the carbs. It's running well but I can't get the idle down much below 1000 rpm. After the video I reset the adjusting linkage and was able to get the idle pretty smooth about 950 RPM. Since this is the first 1300 I've ever worked on, maybe a few of you can have a listen and tell me what you think?

Here is a video I took today...



You will notice there is a puddle under the bike. While I was adjusting the carburetor it started boiling over. I shut it down and let her cool off. My infrared thermometer indicated 260° on the head so she was hot. The problem is the fan was cycling on and off, shouldn't it have stayed on continuously? The temperature indicator never got to "H" mark either but I imagine that old gauge isn't too accurate anymore.

I had been running it for a while, warmed it up, checked the charging system, set the air screws, and was messing with the sync adjustments, goosing the throttle every now and then... so would it be normal for a 1300 to get hot in that situation? Or do I have an issue to sort out?

I would never leave an air cooled bike running like that for sure.

Sounds pretty good to me. Revs straight up and come back down quickly.

Is your water pump working?

Fan should only switch off when it has managed to bring the temperature back down. I had some trouble with my fan not coming on once. The wire from the temperature sender had become so hard and brittle from the engine heat. I replaced the last 6 inches with some new wire and it sorted the issue out

Just a thought regarding the overheating issue. I think that it's possible that you still have some air left in the coolant system and while you're messing around trying to adjust the carbs, the coolant is not circulating fast enough to keep the air moving and you've got hot spots developing in the cylinder head at which point the coolant will start to boil and the steam will seek the highest point in the circuit, the rad cap.

The rad fan cycling off and on suggests that the thermos switch and fan circuit are doing their jobs and the rad is providing enough cooling when at idle to dump the heat generated at idle.

Did you by chance replace the thermostat? I see a few thermostats on EBay identified as KZ1300 stats but they only have one valve like 99% of all the automotive thermostats. This machine to the best of my knowledge has a 2 valve thermostat which opens the coolant circuit to the rad and closes the discharge from the pump to the engine to positively route the hot coolant to the rad and the cool coolant from the rad to the engine. One valve thermostats achieve this circulation route by the sizing of the coolant port sizes such that the circuit to the rad flows easier than the flow to the engine. Ideally, when the thermostat calls for cooler coolant the thermostat opens and most of the coolant in the engine goes into the rad for cooling and the cool coolant from the rad goes in to the engine. This cycle should obvious on the temp gauge. If it's not obvious, then the thermostat could be stuck partially open allowing the coolant to continuously circulate at a lower flow and not fully achieving maximum cooling which will lead to overheating.

Regarding the idle set up- I've found that there's a VERY fine line between the adjustment of the 3 link rods, the idle set screw and the fast idle set screw. when I was setting up my carbs on the bench, I found that I couldn't get the butterflies to fully close and thought I'd messed up installing the butterflies when I changed out the throttle shaft seals. No, that wasn't the problem. Setting the length of the 3 link rods was causing my grief. So I've developed this process for setting the carbs.

1. Back off the idle set screw and the fast idle set screw and adjust the 3 link rods to just take up the slack and this is difficult to see since the link rods have springs in them that appear to take up the slack, so I've found you need to push down lightly on the rods to check the freeplay in each of the rods as you adjust out the slack.
2. Now adjust the idle screw. Take up the slack until the butterflies just start to open, then add another 1-1/2 turns to open the butterflies to basic bench setting as per the manual.
3.- now adjust the fast idle to the measurement as identified in the manual.
4. install the carbs and check your idle, synchronize the carbs, adjust your idle air bleeds etc.

hope this helps,
KB