Hello Freza,
There's a lot there, and I'll leave some of the more technical queries to more experienced people.
1) I'll have to leave this to others.
2) But on point two, I'd start by just checking for things rattling. The fact that it's at a particular RPM, and near the resonant frequency of the bike, suggest it may be this simple. For example I had a similar sound at one stage and tracked it down to on of the chain tensioner things not being, err, tensioned. I.E. it had a little play and would give a metallic rattle at times. Tightened that up and simply fixed. Once you've checked for simple things like this you can then move on to looking at more complex causes if need be.
3) When my front wheel bearings went I had a similar loss of confidence in the front-end, long before I realised they were the problem. It just shows how sensitive we are to the handling that a loss of confidence which you can't quite put your finger on is the first recognised symptom. I'm sure steering head bearings would be the same. I would start investigating this point by checking front wheel and steering head bearings. Put the bike up on it's centre stand and check for play both forward/back and left/right. Ask a friend to put the weight on the rear raising the front wheel, and using just a single finger on the handlebars check fro free movement, and feel for any notchyness. Place the bars centrally and let them fall, doesn't matter if they fall left or right but they should fall all the way by themselves.
4 and 5) When was the last time you had the carbs balanced? Is there any lumpiness at idle? Are the carb rubbers in good order (no cracks etc)? Is the chain and sprocket set in good order? I.E. no tight spots, sticking links, excessive wear?
6) Begin by ensuring lever mechanism is clean and greased. Maybe as simple as some grit in there. Air or water in the fluid would feel spongy.
Hopefully I ask some useful questions to get things started.
Andy
There's a lot there, and I'll leave some of the more technical queries to more experienced people.
1) I'll have to leave this to others.
2) But on point two, I'd start by just checking for things rattling. The fact that it's at a particular RPM, and near the resonant frequency of the bike, suggest it may be this simple. For example I had a similar sound at one stage and tracked it down to on of the chain tensioner things not being, err, tensioned. I.E. it had a little play and would give a metallic rattle at times. Tightened that up and simply fixed. Once you've checked for simple things like this you can then move on to looking at more complex causes if need be.
3) When my front wheel bearings went I had a similar loss of confidence in the front-end, long before I realised they were the problem. It just shows how sensitive we are to the handling that a loss of confidence which you can't quite put your finger on is the first recognised symptom. I'm sure steering head bearings would be the same. I would start investigating this point by checking front wheel and steering head bearings. Put the bike up on it's centre stand and check for play both forward/back and left/right. Ask a friend to put the weight on the rear raising the front wheel, and using just a single finger on the handlebars check fro free movement, and feel for any notchyness. Place the bars centrally and let them fall, doesn't matter if they fall left or right but they should fall all the way by themselves.
4 and 5) When was the last time you had the carbs balanced? Is there any lumpiness at idle? Are the carb rubbers in good order (no cracks etc)? Is the chain and sprocket set in good order? I.E. no tight spots, sticking links, excessive wear?
6) Begin by ensuring lever mechanism is clean and greased. Maybe as simple as some grit in there. Air or water in the fluid would feel spongy.
Hopefully I ask some useful questions to get things started.
Andy