I saw this interesting exchange on an online forum.
I have this 1976 CB 750 that was stored over 25 years. It only has 2600 miles on the odometer so it should be in excellent mechanical condition.
The carbs were all gummed up. I have removed them an followed the cleaning procedures recommended by Mark Shively. However one of the Inlet Fuel Valve springs is stuck. The tiny metal rod that protrudes from the butt or float end of the needle valve is pressed in and no amount of soaking in acetone has freed it up. Is there any way to clean the hardened gum out or do I need to look for a new needle valve.
What other service prochedures should I follow before trying to start this bike that has been stored so long.
Do you have any suggestions?
It looks like the needle valve is rusted in place. Get a new one. Soak them in brake cleaner, not acetone, btw.
You will also need to do the following (if you have not already done so);
1) Replace the fuel line.
2) Reseal the fuel tank.
3) Change the oil, oil filter and air filter.
4) Replace the seals and o-rings in the carbs.
5) Replace the tires and innertubes. They may look to be in good condition, but you won’t think so when they blow out on you while riding.
6) Check and replace, as needed, the manifolds. if they are cracked, then they will leak air and cause problems with the mixture and engine operation.
7) Replace the chain and sprockets if they look even a little worn. Chain and sprockets must always be replaced together or one will cause excessive wear on the other.
8) Clean out all brake systems and replace the fluid.
9) Replace the spark plugs and all fuses.
10) Lastly, go over the entire bike and check all that you can see. If it looks bad, replace it or repair it. And make sure that you have the repair manual when you check these things.
Good luck and ride safe.