Welcome to Part 1
Part 2 is Here
Part 3 is Here

Disclaimer: I am not a technician - just a regular guy who likes to wrench and learn along the way. I rely on the Harley-Davidson Service Manual and other assorted documentation. My articles are to illustrate my experiences and should not be treated as expert advice on how to do a project. Enjoy...

So you want to do a big bore project? Whether you like DIY projects, or want to learn more about how these projects are done, then you have found the right article!

About a year ago, I did a cam replacement write up. I had no idea there was any kind of interest in this area, but a number of notes encouraged me to do a write up and pictorial. Honestly, when I started the cam project, I knew very little about what I was doing, but I was committed to learn. When I say learn, I mean truly understand to the best of my ability the mechanics and science behind what I was doing. The cam project was spread over a few days and honestly I was a nervous wreck during the process.

At the end of the cam project I realized that not only did I have a far better ride, I realized I had learned more than I had ever expected and found enjoyment in the process. I say this because if you are considering doing a big bore project on your own, then I believe your best chance of success is to commit yourself to both learn and enjoy the project.

Again, I am not a mechanic, I will never claim to be a mechanic, and no I did not stay in a Holiday Inn Express last night. If you are a mechanic, or more mechanically inclined than me, then by all means please contribute your experience and suggestions. What I don’t want to accomplish here is to convince anyone that I have any kind of magical wisdom or ability. I leave that to the mechanics that have been wrenching for many years.

During this write-up, I will be very honest with what went right, what went wrong, and some tips to make the job easier. There are many ways to do a project like this and everyone will have a different approach. Kind of like have ten chefs in a kitchen working on the same recipe. Each dish will be slightly different.

Some last thoughts before we jump in. When you are working with anything mechanical, whether it is a motorcycle or a dishwasher, there are risks that things can go badly. Weigh the risks carefully. Be prepared to deal with things like broken or stripped bolts, dropping parts into places that no human hand can reach, breaking parts that are expensive and time consuming to replace – and then breaking them again. No, that is not how this project went, but any project has this potential. If you can deal with these risks, then let’s go.

First, let’s walk through what tools you need and what you don’t need.

· Motorcycle jack or lift table
· Service Manual
· Socket wrench set with ¼ inch, 3/8 inch, and ½ inch drives SAE and Metric – Make sure you have some extensions. I like my 12 inch 3/8 extension a lot
· Screwdrivers
· Combination wrenches
· Ring Expander – cheap and can be bought online and auto parts stores
· Ring Compressor – I prefer the type that is a pliers and band set, but you can use those cylindrical band compressors at the auto parts store
· Torx socket set
· Hex socket set
· Hex wrenches (the ball end variety are very convenient, but not required)
· Dog bone wrench – recommended, but other low profile wrenches or sockets will do the same
· Mechanic Picks - not required but convenient – and cheap
· Rubber Mallet to “persuade” certain parts like the exhaust
· ½ inch swivel socket for the bolts on the exhaust port studs
· Georges Garage or other brand pushrod cover clip installer – Save yourself some time and bloody knuckles and buy one
· One length of ½ inch pipe insulation to protect cylinder studs – got mine at Lowe’s for $1.19!
· Two - half inch PVC union joints – you will see a picture of these later
· Red and Blue Loctite
· Assembly Lube
· Motor Oil, drain plug gasket ring, and Oil Filter
· PB Blaster
· Zip Lock bags
· Black Zip Ties
· Utility Knife
· Wire Brush
· Brake Cleaner Spray
· Sharpie Black Pen
· Lots of shop rags
· Shipping boxes, tape, and lots of bubble wrap – for shipping the engine cylinder and/or heads (Wally World is cheapest)

Some tools are convenient, but you don’t need them. You do not need tools like:
· Crankshaft wrench
· Upper rocker box wrench
· Lower rocker box wrench
· Kent Moore Piston Circlip Installer/Remover
· Piston pin remover
· Piston support plate
· Connecting rod clamping tool
· Torque Plates




Prepping the Scoot for Surgery:

Okay, let’s get all that crap off the bike. The seat, saddlebags, those small color matched side covers, and the right lower fairing, if so equipped, come off. I have a detachable tour pack I removed, just to get it out of the way. Pull the exhaust off and toss the old clamps into the trash.


A note on the exhaust: Removing and installing exhausts can be a complete PITA. Use PB Blaster on the joints and exhaust port stud bolts – it works fast and makes the job much easier. It might not be a bad idea to give everything a spray down with PB Blaster the night before the project.

Tip: Protect the exhaust studs! Yes, they can be replaced, but the risk is damaging them during exhaust removal and installation. I highly recommend purchasing new exhaust stud nuts – they are cheap.

For this project, pull the Maxi-Fuse out. No need to disconnect the battery.


Scalpel Please…

The first thing I did was remove the air cleaner and back plate. For those who already have a stage one air cleaner be sure to save all the O-rings. There is a gasket that might be stuck to the throttle body. If it is in good shape, I’d leave it alone. If not, put it on your list of stuff to buy later.



So many posts go on and on about what a hassle it is to remove the gas tank. On later models it is easy. Follow the service manual procedure to remove your console and then remove all the bolts on the rear of the gas tank, as well as the two bolts on the front/sides. Don’t worry; the gas tank will not fall off. For later models, take a rag and disconnect the fuel line. Only a few drops of gas will seep out. You do not need to go through the process of disconnecting the fuel pump fuse and running the bike until the fuel line is empty.

This is a good point to remove the spark plug wires, spark plugs, and coil (black box the spark plug wires plug into) The coil will come right off. The gas tank bolts secure the coil mounting bracket.

Lift the tank off the bike and take special care to protect the disconnect valve under the tank. It can break. Put a few shop towels under the disconnect valve and prop up the back of the tank a couple inches so the tank does not rest on the valve.

Here is a picture I took later in the project showing how the gas tank is resting. The tank is light if there is very little fuel in it. I sat the tank on a folding table with a rag underneath.



Taking stuff apart is easy. Putting everything back together is miserable if parts get mixed up. I’ve got a pile of plastic bags filled already. Each bag has its contents written with a black sharpie pen. When we reassemble, there will be no searching or second guessing on where the parts go. Let’s keep going.

On the front right side of engine you will see a single bolt on the engine stabilizer linkage. This is the bolt that faces down, not sideways. Remove the bolt and pivot the stabilizer link upward. The stabilizer link is connected to a bracket connected to the front of the engine. You can take the bracket off later.

Right now is a great time to remove the pushrod covers. You need to remove these now so you can see the valve lifters below. Being able to see the valve lifters is important because their position will help determine whether you are at TDC. Observing the lifter position in the down position will confirm there is no spring tension on the pushrods during rocker box removal.



For those just getting oriented to how everything works, it breaks down like this. When the valve lifters are up, the pushrods sitting on the respective lifters are pushing upward on the rockers inside the rocker box. In this position the other end of the rocker is pushing down on a very stiff spring to open a valve. What you have here is a lot of pressure being placed on the pushrod. Removing the rocker box now means you might have a quick spring release causing the pushrod to shoot out the top and being permanently lodged in your nose. Not good. Fortunately there is an easy way to make sure you won’t need an ambulance for you or your bike.

Do you see those pushrod covers? Take a screwdriver and place it in the notch that looks like a screwdriver belongs there, and rotate so the bottom of the pushrod clip angles away from the cover. The clip will come right off. Remove the clip and save it for later.

Tip: If you are replacing your pushrods with adjustable pushrods, your kit might come with new pushrod covers. Do not throw your old pushrod covers away. Some parts will be reused.

With your hands move the pushrod cover up. The covers are telescoping so they will collapse fairly easily. Take a rubber band and prop up the pushrod covers as shown. You can use a clothes line clip too. The goal here is to get an unobstructed view of the lifters.



In my case, I decided to remove my adjustable pushrods for easier viewing of the lifters. Many will have the standard pushrods that will be removed through the rocker plate.



From here it is assumed you are tearing down one cylinder at a time.

Make sure the spark plugs are out. Put the tranny in sixth gear and rotate the rear tire. Let’s start with the rear cylinder. Rotate the rear wheel and watch the two lifters on the rear cylinder move up and down. As soon as BOTH lifters are down, you are at (or near) TDC. You don’t have to be at a perfect TDC, just make sure both lifters are down. A good work light helps here.

You might recall in my cam thread that I emphasized being on the compression stroke. For this application it does not matter if you are on the compression or exhaust stroke. All we want to do is eliminate spring tension.

Let’s remove the rocker box covers. Mine are dirty right now like the rest of my bike, but that is another story. It will take some time to remove some of the bolts on the covers – there is not much space. You will have to use a variety of tools like a hex wrench, combination wrench, and perhaps a dog bone socket wrench to get the bolts out. Don’t worry, it’s easy. Just take your time and follow the sequence in the service manual. If you have the cash you can buy the Screaming Eagle wrenches which make the job go a little faster, but they are not necessary.

To remove the rocker box covers from their gaskets, I placed a microfiber cloth on the surface and give the covers a couple taps with the rubber mallet. Don’t tap hard. You won’t have to.

Here is what you will see.



Here is a close up on one of the rocker boxes. As you can see removal is straight forward. Remove two breather bolts in the middle and then as indicated in the service manual remove the rocker bolts. The assembly will lift right out.



Follow the same procedure with the rocker box support plate. Use the tools you need and take your time. It is not difficult. Lift out the rocker boxes and set them aside. Use those shop towels to clean any excess oil off.

Here is what you will see:



For those with stock pushrods, you can remove them now. Remember to rotate the next cylinder to TDC before removing the rocker box. Rotate the rear wheel until both lifters are down.

Follow the service manual and remove the rocker housing bolts. You are six bolts away from getting to the head! Here is a picture of both rocker assemblies removed.



Because space is so tight, keep a hex wrench hand to remove some of the rocker support plate bolts. The Screaming Eagle rocker box wrenches are designed for these tight fitting spaces. They will be useful but not required.



If the rocker support plate is stuck to its gasket you can lift it off with a small pry bar using the fins as leverage. Use some masking tape so don’t scuff up the chrome or powder coat. You won’t have to pry very hard to break the gasket. Here is what I used before I taped it up.



Let’s do some quick housekeeping. I bag the left and right rocker box hardware separately. Do you need to do this? No, but I want everything to go back together the same way it was removed. This is a good point to mark your rockers front and rear.



Remove the four head bolts as specified in the service manual. You can now remove the head. Lift up so the heads clear the cylinder studs. The heads should separate from the gasket easily. The heads have some weight to them; maybe twelve pounds each. Interestingly when I shipped my heads and pistons for work, both cylinders weighed less than both heads.



Here is a picture of the combustion chamber and valves on the bottom side of the head. There is some carbon; still not looking too bad for a stock head.







That's it for section one. I will post section two later on and make sure you can link from one thread to the other.

 

Subscribed for future reference. Thanks for the detail that you have covered. Very comprehensive!

 

man that is some great work really descriptive. Really nice job posting pics. Still not sure if I would tackle that job though. So how did it run after.... inquiring minds want to know????

 

Great job with pictures and descriptions. I will be using your pics and instructions to do my BB kit this week.

 

Subscibed