Ticking Evo Tappets



An annoying tick in your Evo Big Twin motor that doesn't seem to affect reliability or performance might be a hydraulic tappet (lifter) noise. Hydraulic tappets in the Evos are very strong, quite unlike the weaker ones used in their Shovelhead predecessor. However, there are a couple of things to look at, especially with the front exhaust lifter which is the one closest to the front exhaust pipe. You will notice that the intake lifters, (the two middle ones closest to the carb), are almost straight up and down. These two are always okay if the hydraulics are in good condition The rear exhaust lifter (The only one left) is at an angle greater than the intakes but not as great as the front exhaust. The hydraulic lifter is weaker when on an angle. The tick you hear is probably from the front exhaust because it is not pumping up fully with oil to take up the excess clearance between it and the hard working pushrod. In 1984 and '85, the lifters were not always up to snuff in the pump-up strength department. Harley fixed this problem in 1986 with a beefier version, (part #18523-86), that has worked very well. Harley also has a beef-up kit for the '84-'85 problem lifters. You can also get solid lifter replacements kits to eliminate the problem forever.

So what to do if you have a tick?

If it's caused by early lifters, put in the later ones, which work great.S&S or Sifton lifter limitor kits will quite often solve the problem easily and inexpensively. Install a limiting ring into each lifter. These are metal circular rings that give solid lifter "no bleed down" qualities but allows for hydraulic lifter quiet operation. High RPM riding especially with higher lift cams can cause the hydraulic lifter to "bleed down" leaving a little too much play with an ensuing clatter noise will quite often be solved with the "limitor" approach. Still plagued with the annoying tick and it is determined that the lifter is not weak, then a solid application with an adjustable pushrod will do the trick. This can be done to the front exhaust while leaving the other three hydraulic if you so choose.


Source: http://www.heavydutycycles.com/ticktapevo.htm