Daz- Everything you have outlined I experienced. On my recent cross country round trip, my squeaking worsened. At first WD40 helped, then not at all. The belt tightened so much after riding an hour or more, that it was scary. (Before leaving, I had a new tire put on the rear wheel, and that's when the problem started.) I tried adjusting tension after a few days, and after a few days more... Whenever I slowed down to going through towns etc., the noise was almost embarrassing. On the last day, heading back back from Indy to Mass, I finally hit the adjustment right, where the tension of the belt did not get seriously tighter over time, and the squeaking all but disappeared while crossing PA. So, in my case, I think it's not so much the lubrication, but rather the balance of belt tension and wheel alignment. You mentioned a new way you have of establishing/checking alignment. Care to share?
Sounds like the exact experience as me. So far today after having aligned it and adjusted the tension lower it's doing fine. Tho like you i had to I had to find that balance. But thats easy enough....just adjust it when hot ! Then i should never get tighter, tho then again who knows.....maybe they tighten to different degrees depending on certain things like air temp or who knows what. In any case, i did that but when cold it's very loose. However i will just take it easier when cold for the first 3 or 4 miles and by then it should tighten up enough to ride any way i want. but i gotta tell you, i'm still stumped as to how triumph can spec the tension so frigging tight when cold knowing that it gets probably 50-60% tighter when hot ! Like i said earlier, maybe being out of alignment it would make it tighten even more due to excess heat from the teeth and grooves not being parallel. But after work i checked it and then when i got home, and the difference may have been not quite as wide after the alignment, but it wasn't a lot better. Then again it was 100 today ! So maybe the heat had some influence. I will have to keep checking it.
As to the alignment, there is a hole in the swingarm right next to the belt guard mount closest to the enging. Look just about a 1/2" form where the guard is mounted and you'll see a hole about 1/4" in diameter. On the other side of the swingarm there is also a hole. actuaklly 2, but you want to use the one that looks like the one on the guard side, NOT the one that has a little metallic collar in it. You could do this with a screw or peg of some kind in the hole and wrap a string around the peg them measure to the center of the axl and mark the string, then pull the peg and string and put it in the other side and see if the mark matches. I did it in a way that i think makes it simpler and quicker. I took a length of solder, bent the last 1/2" at a sharp 90 degree angle and put that 1/2" part in the hole and held it there tight with one finger. With the other hand i pulled the solder taunt (not so tight as to stretch it tho !) and brought it down across the axl. Then i held it in place there and let go of the part in the hole so i could use that hand to mark the solder. I put a dent in it there with a screwdriver to mark it sharply. The to make sure i put the L part back in the hole and rechecked it to see exactly where the mark was. If it's not quite in the center of the axl, no problem. Just remember if it was a littl forward of backwards from the center. Now check the other side and if it doesn't match up, adjust. Once they seem the same, adjust belt tension. Once tension is right, recheck alignment. Then when tension and alignment are both spot on, tighten the axl. By the way, 2 hints... 1-if the nut on the left side needs to come back out, after you turn it, sit in back of the bike and kick the tire otherwise there will be a gap between the nut and the swingarm because on the left side axl will not be pulled forward by belt tension like the right side. and 2-when you tighten the axl nut, do NOT pull up ! Only push down. So you will need a socket extension. Other wise the torque wrench will hit the shock on the way down. So about a 3" extension or there abouts. the put the wrench on the nut with the handle at 12 noon strait up and push it down towards the front of the bike. Only tighten it that way. If you put it on with the handle pointing to the back of the bike, when you pull up it puts pressure on the axl that forces it back away from the front of the bike and throws the alignment out. Thats why if you don't do it that way, next time you go to adjust that side you will find the nut is loose instead of tight against the swingarm.