Friday, May 7, 2010

Replacing Harley Lifters

It was time to do the lifters on my 94 Evo and decided to make a tech article for all those who, like me, love tech articles.

This was my first lifter job, so if you see something fishy, please comment!

  1. Disconnect the battery (if so equipt :) )
  2. Put the bike on a lift such that the rear wheel can turn (this is important later)
  3. remove the spark plugs to you dont have to fight compression.
  4. Remove any interference (air cleaner) and throughly clean the area around the lifter guide block, the push rod tubes, and the head/cylinder.
When facing the motor, the front and rear pushrods are the exhaust and the inner two rods are the intakes.

The top parts of the pushrod (PR) tube are the first to go.  The little loop on them is so you can insert a screw driver and twist so the bottom comes out.  Remove all 4 of them and set aside.

I will do these front to back, so I have to get the front cylinder on the compression stroke (both valves closed) so I know the lifters are riding on the cam base and not up on a lobe.
To do this is pretty easy:
  1. Push the rod covers up and hold them with a clothes pins so you can see the rods.
  2. Now just put the bike in a high gear (4th or 5th) and slowly turn the rear tire to roll the motor.
  3. Watch the rear cylinder rods.  When the exhaust comes down and the intake starts to come up on the REAR cylinder, the front cylinder is on the compression stroke.

 I just want to add here that each PR is different and I have heard that the lifter guide block bolts are too.  So what I did is keep everything layed out as it came out.  You will see as I progress.

Now loosen the lock nut and start compressing the rod.  Mine were a real pain and took a long time to get it all screwed together but it beats taking the tank off, removing the rocker covers and the rest if I had solid rods.  (if you have solid rods, stop here and get some bolt cutters and remove them that way.  Buy some adjustable rods and skip ahead)

 Now that both front rods are removed, I layed them out in order.  I like putting parts back exactly where I found them.  They are happier that way and don't get all mad at me later.

Remove the 4 - 3/16 allen bolts holding the guide block on and set aside (again, anal me layed them out so I could put them back in the same holes.
Now I had to take a rubber mallet and GENTLY tap the lifter guide block to break it off the gasket.  

Here is a shot of the new lifters.  The "B" lifter (note the part number) is sufficient for all motors except maybe a stroker or wild cam...wouldn't know about those, I'm just a poor biker.

Note the differences between the old lifters I pulled out and the new ones.  The old one is on the left.

The oil hole is 90 degrees out on the new one, and the axle is significantly beefier.

 After getting the block off, note that they marked the underside with "front" and "rear"...I like idiot proof.  Clean the block up and make sure that the oil channel is clear.  Remove the old gasket material on both the block and the engine case. DONT let crap fall into the case!

I though that now was a good time to check the cam shaft end play.  Stick a feeler guage on the inner side of the cam, between the cam and the case.  My book says .001 to .050 which is a HUGE amount of slop for an evo, just as reference my shovel specs are .001 to .016.

This one measured .013 which is pretty good for an older bike I think.

 To get ready for replacing the rods, you will have to know how much to preload the lifter.  A stock HD lifter has .002 inches of travel as it pumps up so we want the rod to preload the lifter right in the middle of the travel.  That is .001 inches of preload.  Here I am measuring the Threads per inch on my push rod so I will know how much to turn it after I reinstall it to achieve that .001

I missed pics of the actual removal and re-installation of the lifters, but it ain't that hard.  The only warning here is DONT let the lifter fall into the case.  They come out from the bottom and you will have to keep them in the guide block when lifting it out.  I did this by taking a large paper clip and bending it into an upside down U and then bent a small 45 on each end to "hook" the lifter by the oil hole and pull the entire thing out carefully.

Now there is some discussion on pre-filling the new lifter, soaking it (which doesn't do anything, really), or just inserting it right out of the box.  I just cleaned off the shipping oil with a light machine oil and put them in.  I know that for a few seconds the top end will be oil starved, but if the system works like it was designed they will be bathing in it pretty quickly.  I ain't scared.

Put the lifters in, put on a fresh gasket (MAKE SURE the oil hole isn't covered by the gasket, if it is you put it on wrong), and then seat the guide block (using the paperclip method again).

Bolt it down and torque to "two grunts".  I think it is 90ft-lbs, but I dont have a torque wrench that will reach the inside two bolts, so I just winged it.

Now ensure that the pushrods are clean and the oil path down the center isn't fouled, I found one with a little sludge in it.  Nothing a little wd-40 couldn't blast out.

When inserting the rods, just get them in place and start unthreading them (making them longer).  You can figure this part out.  When about there, ensure that the top of the rod is seated well into the rocker and not beside it.  You can feel it, feels like a ball and socket joint. (which it is).

Now comes the tricky part.  Getting it set right.  Stock lifters spec out at .200 travel inside the lifter, so we want to set the rod right in the middle of that depth.  (that is .100 for the mathematically challenged).

From the thread count I found above, 36tpi, I calculate 3.6 complete turns for .100 inch.  (36 x .1)  if I want to get really accurate, I multiply that by 6 (the wrench flats on the rod) and get 21.6 flats.

We havn't moved the cam and it is still riding on the base and not up on a lobe, so we are good to start this part.  Extend the rod so that it is finger-spin tight, no load but no movement up and down.  That is the Zero Lash point.  Now extend the rod 21.6 flats, tighten the locking nut and call it done!  I had some trouble getting the locking nut tight and not changing the length of the rod, but If you work at it you can get it....I did and I am stupid.

NOTE: Do the intake rod first, it is really hard to get to after the exhaust rod is in.

Once the front cylinder is done, start at the beginning of the procedure for the rear set.  (rotate the wheel until the rear is on the compression stroke and remove the rods, etc).

Good luck and get greasy!  I was at a crab shack last summer and some of the local shop boys were there.  I overhead "naw, he does all his own work..." not sure how the rest of the conversation went, but I felt proud about that reputation of not being dependent on some shop tech to get my ride on the road.  hopefully you are too!


ridehard said...

The lifter block bolts are in in/lbs not ft/lbs. Do not over tighten these. If you strip one you are up the creek. I use TDC for the cam position is indication and you can see the mark in the flywheel inspection/timing hole on the left case.
Is the lifter travel .002 or .200? Big difference. I soak the lifters in oil because.......why not? Too much oil can be a good thing. Too little is not.
However, if you do soak them you MUST let the lifters bleed down before going to the next cylinder. Just leave them alone after you have adjusted the preload until they spin with little or no drag. Takes 10-20 minutes. Have a beer and wait.

Anonymous said...

Lifter block alignment is part of it also .. A special alignment tool that is tapered and threaded replaces two of the fasteners while the other two fate ERS are installed .. Remove and repeat ... Probably could fab one up... No alignment pins or dowels on evo blocks

tom conner said...

You can simply scribe around your blocks to re position them its not as critical as you would think mainly keep the rollers and cam tracking perpendicular or lined up parallell with the cam lobe surface, but if it sells a high priced specialty tool hey someone has to have it in their brag box