Motorcycle Repair: no power in my 1970 Honda CL 350, honda cl 350, rust check

Question
Hello,

I gave my scrambler a valve adjustment and it ran great for a day
and a half. Then it suddenly stopped running well. It has no
power and wants to stall. I have to wind it out in first and second
gear to get up to 30. It's like the carbs aren't getting any air or
something. And in fact, the choke was trying to close on it's
own; I had to hold it open with my finger while riding. It had
never done that before. This may be an unrelated problem,
though.

It had sat unused for about 6 months before the adjustment, but
I did put fresh gas in it. And as I say, it ran well for awhile. What
can happen when gas sits in carbs for a long while, and what
should you do about it? Could this be the problem? And if so,
why would it run well for awhile, then crap out?

Thanks for your help.
NB

Answer
Nate, you have to go back to the basics..
Check the valve clearances again and be sure that you have even compression on both cylinders. The adjustment locknut may have loosened up. Be sure to set the shafts so the marks are -\ and /- when viewed from the side.

Next, check the ignition timing to see that the points are clean, opening at the F and LF firing marks. Observe the points when the engine is running to see that they are not arcing excessively. If so, then the condenser for that side is either failed or the lead is loose up at the coils.

Look at the carb choke link. There is a bunch of stuff running down there and it can interfere with the choke linkage, causing them both to run closed.

Read the plugs and see what they look like. If you ran it with a lot of choke on, they may be fuel fouled. Replace them.

Drain the carbs at the float bowl drain screws, catch the fuel coming out and look for water or dirt/rust. Check the floats to see that they are not sinking for some reason if you have to pull the bowls off. Any carb overflowing is caused by dirt in the float valves, generally.

Take the carb tops off and check for a failed rubber diaphragm. Any tears or pinholes will cause problems.

Gas sitting for 6 months evaporates leaving varnish and deposits inside jets and passages. Always use fuel conditioner when going into storage or drain the carbs.

Bill Silver