Before adjusting valves and setting point gap, my bike got up to 50-60 ok. Now when I shift from 3rd to 4th and get up to about 50MPH the bike acts like it has a rev limiter installed. I went over the valves again and set intake at .006 and exhaust at .008. The bike kicks 1st or 2nd try and feels good in other gears. I am not sure what is wrong.
I wish I knew more specifics about the singles, so don't know if there's something unusual on them as opposed to the twins.
Is all that you did was set the valves and point gap? It worked fine prior to your work? If that's the case, then it's usually something associated with the work you did.
If that was happening on my /2, I'd probably be sure that the timing was working correctly. You said it starts good but I wonder if you're not getting the proper advance at RPM. The advance weights must move out to their proper limits as the RPM goes up. Be sure the advance weights can move freely.
The valves were set at TDC on the compression stroke? With the single cylinder, you don't have to worry about which side is at compression. When you set the valves, were they pretty close from the last time you set them or did you have to make a biggish change? If you had to make a big change, I'd wonder if something wasn't in the right position for setting the valves.
After that, I'm thinking about a plugged air filter or maybe the throttle is not opening as wide as before, but that seems unlikely if you only worked in a limited area.
Well, that's some thoughts...
Kurt in S.A.
Glad you found the bad condensor. The condensor does tend to be overlooked.
I would think that you'll need a timing light to see where the full advance mark is, but you'll also need to know what the RPM is at that point. I suspect you don't have a tach.
To change the timing, you would likely rotate the whole mechanism CW or CCW depending on what you want to do. If if the bikes gets too advanced, then you're going to get pinging. Then you could back off the advance until the pinging goes away. You may need to make an adjustment, ride it, come back and change the adjustment, etc.
One thing you might do to check timing at full advance is similar to what you may have done for static timing. I suspect what you've done is adjust the point gap and/or timing plate so that the points open just when the "S" mark (if that's what it is on a single) appears in the timing windown.
Conceptually, the same thing could be done for full advance. But what you would do is find something to hold open the swinging advance weights. I've used broken pieces of toothpicks to wedge into the sides of the weight and against the body of the advance unit. With the weights completely at their full travel, you can then repeat the check for when the points open. But this time, you should expect to see the full advance mark in the timing window when the points open. If not, then you need to adjust the timing plate so that happens. Then you can remove the toothpicks and recheck the static timing.
Static timing is not so critical, except that it must be in the ballpark to get the bike started. Since you spend so much time at full advance when riding around, you really want the full advance timing point to be accurate.
That's my ideas...Kurt in S.A.