Top End
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From: Cincinnasti
Top End
I was wondering if someone could tell me what all is involved in performing a "top end" job. My '73 XLCH is showing signs of an oil leak coming from above the #1 Cylinder exhaust port. I figured that in the last 3 yrs. that i've owned her, I have only rebuilt the carb., adjusted pushrods, set timing... you know, the typical yearly routine stuff. But was thinking since I don't know her history, maybe a top end work over may be in order. Any help would be appreciated.
Stellar HDF Member
Joined: Feb 2006
Posts: 3,035
Likes: 17
From: Houston Texas
Just briefly......... it is not too big a job, but you need to get a factory service manual before you do it.
The steps are clearly laid out in the manual and the order of operation are as follows:
You have to remove the fuel tank.
Remove the exhaust pipes.
Remove the carb and intake manifold.
Remove the push rods and push rod covers.
Remove the front head and rocker box. Together, or as one unit.
Remove the rear head and the rocker box as one unit.
The rear head and rocker box gets re-installed as one unit also. This is because of lack of clearance with the frame spine tube.
Unbolt the 4 nuts at the base of the cylinders. Be sure to mark the cylinders front and back so you do not get them switched.
With the piston at the top of it's stroke, raise each cylinder off the crankcase enough to stuff clean rags all around the rods. This will keep broken rings from falling into the bottom end.
Should that happen, you will have to remove the engine and take it 100% apart. So be careful and get rags in there.
Then raise and remove the cylinder(s).
The heads will most likely need a valve job. If they need new valves then buy new springs as well. The heads are going to possibly need new guides also. This is where oil may be coming from in the exhaust pipe.
You need to take the cylinders to a shop and have them measured with a bore gauge to determine wear. If worn enough, they will require reboring and new pistons/rings. All of this is a worst case senario. Maybe yours will be in good shape inside......... pg
The steps are clearly laid out in the manual and the order of operation are as follows:
You have to remove the fuel tank.
Remove the exhaust pipes.
Remove the carb and intake manifold.
Remove the push rods and push rod covers.
Remove the front head and rocker box. Together, or as one unit.
Remove the rear head and the rocker box as one unit.
The rear head and rocker box gets re-installed as one unit also. This is because of lack of clearance with the frame spine tube.
Unbolt the 4 nuts at the base of the cylinders. Be sure to mark the cylinders front and back so you do not get them switched.
With the piston at the top of it's stroke, raise each cylinder off the crankcase enough to stuff clean rags all around the rods. This will keep broken rings from falling into the bottom end.
Should that happen, you will have to remove the engine and take it 100% apart. So be careful and get rags in there.
Then raise and remove the cylinder(s).
The heads will most likely need a valve job. If they need new valves then buy new springs as well. The heads are going to possibly need new guides also. This is where oil may be coming from in the exhaust pipe.
You need to take the cylinders to a shop and have them measured with a bore gauge to determine wear. If worn enough, they will require reboring and new pistons/rings. All of this is a worst case senario. Maybe yours will be in good shape inside......... pg
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Intermediate
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From: Cincinnasti
Cool. I appreciate that pg... Doesn't sound all that difficult. Just need to find a time when the local shop is slow. Busy time right now with everybody slowly digging out from a cold winter. Do you just use a honing kit if bores aren't too bad or out of round?
Stellar HDF Member
Joined: Feb 2006
Posts: 3,035
Likes: 17
From: Houston Texas
If the cylinders are out of round then most likely the clearance is going to be on the loose side (too much wear) and a bore and new pistons are needed.
Honing a cylinder is used for busting the glaze that can develop which can keep the rings from seating. And honing only makes the cylinder larger in size (to a small extent) which is not what you want if you already have appreciable wear present. I prefer to remove the glaze by hand sanding a X pattern with a piece of 400 wet/dry paper in each bore.
When you remove the cylinders the piston skirts will most likely be the first thing that will tell you if there is a problem.
If the skirts are scored up badly then just prepare yourself for a rebore and new pistons.
Sportsters get scored pistons very easily it seems. Sometimes because not enough oil getting to the piston/cylinder walls or perhaps from running the bike hard before it warms up to operating temperature.
And all it takes is doing this one time. There is no going back when you have scored a jug or piston skirt........... pg
Honing a cylinder is used for busting the glaze that can develop which can keep the rings from seating. And honing only makes the cylinder larger in size (to a small extent) which is not what you want if you already have appreciable wear present. I prefer to remove the glaze by hand sanding a X pattern with a piece of 400 wet/dry paper in each bore.
When you remove the cylinders the piston skirts will most likely be the first thing that will tell you if there is a problem.
If the skirts are scored up badly then just prepare yourself for a rebore and new pistons.
Sportsters get scored pistons very easily it seems. Sometimes because not enough oil getting to the piston/cylinder walls or perhaps from running the bike hard before it warms up to operating temperature.
And all it takes is doing this one time. There is no going back when you have scored a jug or piston skirt........... pg
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Intermediate
Joined: Mar 2009
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From: Cincinnasti
Great. Again, thanks for all your help Pinion. You truly are a blessing to us younger guys. Well I'm 35. But I'm still full of **** and vinegar. And I'm too hard headed to let anybody else touch my bike or either one of my cars. If a bolt falls off (Loctite on everything) then I want it to be my fault.
Stellar HDF Member
Joined: Feb 2006
Posts: 3,035
Likes: 17
From: Houston Texas
I totally agree. If something goes wrong I like to keep the circle of blame in a very tight diameter........ just around myself.
However, I am getting old enough to approach letting someone else install a new rear tire on my Dyna.
It's $100 labor, but that sounds like it will be well worth every cent for such a job. That is the type of work I can easily avoid, if possible.
pg
However, I am getting old enough to approach letting someone else install a new rear tire on my Dyna.
It's $100 labor, but that sounds like it will be well worth every cent for such a job. That is the type of work I can easily avoid, if possible.
pg
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