I'm stuck with this '75 R90/6.
This is what's wrong:
It starts fine, and when I have the rear wheel jacked up the bike goes through its gears smooth and easy. When I get on it for a ride it will stall unless I give it near full throttle but when I get into 2nd and 3rd the 'stalling' becomes slightly less at each gear.
This is what I've done so far:
Checked the timing and it seems to be fine. The only problem is that the bike is dual plugged and has a DYNA 3 ignition on it, so trying to find the correct information on where to set it is frustrating. I've been through 'Snowbums' explanation and many others and I'm pretty sure that I have it set correctly.
Checked the valve clearances and they were within .001 inch of what they should be.
Checked the compression and both sides are near 120 PSI (within 2-3 PSI of 120)
This is where I think the problem is:
I went to check the balance on the carbs (32mm Bing CV's) with the "$4.00 carb balancer" and the right carb damn near pulled the oil into it (glad that I'm quick with the kill switch).
Ultimately I put a vacuum gauge on the carbs (It's a dial gauge and it bounces all over the place) and on the right side I got about 15 PSI of vacuum on the high end and 10 PSI on the low end, but on the left side I was getting 15 PSI of vacuum on the high end but on the low end the gauge was showing a positive pressure of 5 PSI.
The carbs were rebuilt 2 years ago and I figured that everything was still ok in it, but I tore into them anyways. The diaphragm is in good shape and all of the O rings are good (I didn't go into the throttle body because I figured that if the other O rings are good they are good too).
I replaced the carbs and tried spraying starter fluid on left one while the bike was running but I didn't get any increase in RPM.
Sorry for the book above but right now I'm at a complete loss, so any insight will be greatly appreciated.