After further review it may be an issue with the carbs somehow. Went back to the aux tank and it wasn't filling the fuel lines all the way. What could I have done to the carbs to create some sort of back pressure that isn't allowing fuel in?

Well I've solved all my fueling and hose issues and actually got to ride and enjoy it a bit. She sure likes to back fire a lot when the revs come down: is that a sign of being too rich? One thing that worries me is it doesn't like to shift from 2nd to 3rd under power.

Hopefully I can start considering paint in a few months.

Its going to look great when its painted.
I had a similar problem with the gear change on my B4, i found a tiny adjustment to the angle of my gear lever made a huge difference to the change.

Hmmm, I'll give it a try.

backfiring is usually a symptom of running lean, however if you have a misfire it can happen also as i found out when i was riding back home with a misfire i was backfiring and shouting flames at the same time lol

Here is an ugly update-
I was riding the bike but was getting a lot of backfiring when I let off the throttle and let the revs come down. I rode it down to a mechanic friend and he listened to it and said it almost sounded like it wasn't running on all cylinders.

I pulled the plugs and 1&4 looked very rich and 2&4 looked perfect. We thought we might have a bad coil because one supplies 1&4 the other 2&4. I got the coils, installed and ready to ride and guess what; bike won't even hint at starting.

Spark looks good on all 4 cylinders (same issue when I stuck old coil back in too). Fuel is getting to the floats. Plugs are pretty dry though. Went through the carbs and found no obvious blockages. Mixture screws 1.5 turns out. Won't hint at starting with choke on, off or with throttle.

I'm knee deep in GK76 carb trouble!

Just remembered this, when the mechanic was messing around with the mixture screws he was turning them every which way and not getting any change in the way the bike was idling and which was strange.

I haven't made much progress and am still chasing a non starting issue. Started thinking it may be electrical, then carb related and now may be compression related as the carbs are full of fuel but it isn't getting sucked into the cylinders. Did a quick compression test and 1,2,3 cylinders came back at over 150PSI and number 4 came back at 100. Before I put a little oil into the cylinders though they all came back at 100PSI. I'll find the damn issue yet! Anyways, riding weather has passed so I have some time to figure it out.

I missed out (got outbid) on a neat Autorimessa chin radiator out of Japan. I have no need for it but I like collecting the old race parts.

how about the pick up coil?

Have you tryed to bump start it? After i rebuilt my engine it wouldn't start with electric, but it bump started no problem then electric start was fine after that :/ May just have been a weird thing after what i did but worth a try.

Did the coils not fix it?