1970 flh When the throttle is backed off the valves make a tapping noise, is this normal?
Your engine is equipped with hydraulic tappets and they shouldn't make a noise however, a 1970 model had probably got a lot of miles on the entire engine unless it's been overhauled. Even then, a lot of mechanic overlook a few things that would cause that problem.
First let's start by adjusting the valves. Take the plugs out of the engine and raise the rear tire off the ground. Put the transmission in fourth gear and bump the engine over until the front cylinder is at top dead center. Remove the pushrod tubes. Loosen the lock nut on the pushrods and back the off until they are completely loose. Then, turn the adjuster downwards until all the slack is our of the pushrod. Then continue turning the adjust exactly four more complete turns and lock the lock nut. Do the same with the other pushrod for that cylinder. Allow time for the hydraulic units to bleed down until you can spin the pushrods with your fingers. Now, you can turn the engine over.
Turn the engine over until the rear cylinder is at top dead center and adjust the pushrods the same way. Once finished, reinstall the pushrod tubes, spark plugs, put the transmission in neutral, and lower the bike. This should stop you ticking if pushrod adjustment was the problem.
Now, the hydraulic tappet units just sit in the top of the tappets. While you've got the pushrods loose, you can take the hydraulic units out of the tappet. To test the hydraulic units, pull it apart and use mineral spirits to clean all the oil out of the unit. Blow the unit dry with compressed air. Put the unit back together and squeeze it all the way together and hold it for ten seconds. If the center pops back up when you release it, the unit is good. If the unit bleeds down and does not pop back up, the unit is worn out.
Another source of "ticking" in the valve train is the rocker arm bushing and shafts. These wear rather quickly. If they are not replaced, they will make a ticking noise. Other than that, there is nothing that will cause he valve train to tick. Now, you can lose a roller bearing on the cam end of the tappet but it'll make a knocking type noise much more noticeable than a ticking noise. Hope this helps.
Nov 11, 2010 |
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