Our main focus here at Common Motor is putting vintage Hondas motorcycles produced from the mid 1960's to the late 1970's back on the road. Over the years we have looked at "metric" tons of vintage motorcycle projects; whether it be a Honda, Kawasaki, Suzuki, Yamaha, Ducati, Moto Guzzi, Ural or BMW (just to name a few). We have seen more than our fair share of old motorcycles beyond a quick glance, all of these machines need an ample amount of parts and labor to become road worthy again.
The following list is a rough guideline of the parts and systems that should be addressed on every vintage motorcycle that has been dormant (non riding condition) for years. That being said, just because a motorcycle "looks to be in good condition" does not mean that the parts and systems mentioned below are in proper working order. Thus do not assume because a bike is in cosmetically good shape, it it also in safe mechanical condition to ride, which they typically are not.
It should be noted that every specific motorcycle has a different history of use, maintenance (or neglect), and typically there will be more things to repair and parts to replace that the list does not encompass. Issues beyond the laundry list are on a case by case basis depending on the condition of your motorcycle and preferences you have as an owner. Our philosophy here at Common Motor is that every motorcycle can be fixed, given enough time, energy and parts. Regardless of manufacture and specific model, there is a commonality between all vintage project motorcycles in regards to the parts and systems of the bike that will need to be addressed in order to make a reliable and safe machine that performs as good as it did when it was new.
We have divided the list into subsystems and included links to supplemental information for further reference as well as links to the parts mentioned in each section.
It is the various rubber and plastics of the fuel system on a vintage Honda that are prone to decay beyond use. Rubber will shrink, dry out, and crack with age, allowing for fluids to drip and air to leak though places it's not supposed to. The following rubber pieces are what you should expect to replace on the fuel system of every vintage Honda motorcycle project.
- Fuel Line - Old fuel line will harden and or crack, thus allowing fuel to spill and seep out around carburetor inlets, petcocks (fuel valve) and fuel cross over tubes. Fuel line / hoses typically only last a few years at best and are changed out regularly. Luckily it is an easy repair and fuel line is inexpensive. We opt to use polyurethane fuel line over vinyl or rubber hose as it fits better, is resistant to heat and stays flexible with exposure to gasoline over time.
- Gas Cap Seal -This one is not so obvious as it is a little out of sight, it is only when an old seal allows gas to spill all over your tank and lap that you may realize that it needs to be swapped. Gas cap seals must be soft and compressible to work properly. Depending on the cap gas cap style and condition, it may be best to replace the whole cap. There are two common gas caps used on vintage Honda's, the latched flip up style and the round twist on style
- Petcock O-rings & Gaskets - Petcock aka fuel valve separates the gas tank to the carburetors. Only a few o-rings and seals make the simple part work, however they are commonly dried out and let fuel drain out of the tank like a hole in a bucket. If the petcock is in good shape it may just need fresh rubber parts and cleaning to be in good working order again, however other times the base metal of the petcock has corroded to dust and is not salvageable. If the latter is the case on your bike the whole part should be replaced. There are a few different petcock designs used on the vintage Hondas depending on the model and tank style used.
Petcock Rebuild Kits
CB175 / CB200 Rebuild Kit - Coming Soon
CB350 / CB360 / CB450 Rebuild Kit
CB550 / CB750 Early Style Petcock Rebuild Kit
CB550 Late Style Petcock Rebuild Kit
CB175 / CB200 Petcock - Coming Soon
CB350 / CB360 / CB450 Petcock
CB550 / CB750 Early Style Petcock
CB500T / CB550 / CB750 Late Style Petcock
- Carburetor O-rings, Gaskets, Floats & Brass components - Carburetors tend to be the first thing people attack when fixing a vintage Honda motorcycle. Whether it has been few decades or a few months (gasoline starts to degrade quickly, just 6 - 12 weeks), the carburetors need to be cleaned and sealed back up with fresh O-rings and gaskets at a minimum. This assumes all the brass parts in the carburetors are in good condition and thus able to be used again, if not then a full rebuild kit for each carburetor will need to be utilized. Floats are subject to inspection and testing as well.
Carburetor O-ring Kits
Full Carburetor Rebuild Kits
CB175 / CB200
CB350 / CL350 / SL350 K0
SL350 K1 / K2
CB360 / CL360 / CJ360
CB450 / CL450 / CB500T
CB550 / CB500K Early Style
CB550 K3 & K4 Style
CB175 / CB200
CB350 / CL350 / SL350
CB450 / CL450 / CB500T
CB550 Early Style - Coming Soon
CB550 / CB750 Late Style
- Carburetor Diaphragms - If you motorcycle has CV (constant velocity) carburetors, like the Honda CB350 and CB360 family of bikes, the main carburetor slide is controlled by a large rubber diaphragm. If you are lucky, these are in good condition and may be able to be used again. There is about a 50/50 chance they will reusable or replaced. Original diaphragms need to be pliable and slightly stretchy with no pinholes, tears or splits. If in doubt, swap them out.
- Intake Manifolds - This is one of our top recommended parts to swap out on any vintage Honda motorcycle. This is another one of those parts where people take a glance at them and assume they are good to use again, which is never the case. These big hunks of rubber, dry out and become really stiff. Thus they will not properly seal between the carburetors and the cylinder heads, causing vacuum leaks and engine tuning headaches galore. We can not emphasize swapping these out enough, just do it and avoid taking hard road.
CB350 / CL350 / SL350 K0 Intake Manifolds
CB360 / CL360 / CJ360 Intake Manifolds
CB450 / CL450 / CB500T Intake Manifolds
CB500K / CB550 K0-K2 / CB550F Intake Boots
CB550 K3 / K4 Intake Boots
Tires, Inner Tubes, and Rim Strips - This one should be a given, yet we see a surprising amount of people ride off on 40-year-old tires solely because they "still have tread on them and they hold air." Like the other rubber pieces on the motorcycle, tires have limited life span, as time dries out rubber making rock hard donuts rather than the pliable soft pavement traction device they were at one time.
Old tires can also develop flat spots from sitting even a short amount of time when not inflated properly, sidewalls weaken from age, and noticeably crack. Inner tubes and rim strips will also fall victim to the same problem of rubber decay. Do not take a chance! Replace your tires, inner tubes and rim strips all at the same time. Just remember when you only have two tires, maximum traction and safety are critical.
Inner Tubes & Rim Strips
The front and rear braking systems are easy to skip when all you can think about is getting the motorcycle to go. More importantly, is being able to stop the motorcycle once you get going. Brake system components need to be changed. Period. Brake systems are another part that will suffer and decay from age.
Hydraulic Disk Brakes - Because these are under such high pressure from the hydraulic brake fluid, old rubber components in these systems can are at a dangerous risk of failure.
- Hydraulic Rubber Brake Lines - Any signs of cracking, abrasions or stiffness, means these hoses need to be replaced. A good rule of thumb is, If the rubber hoses are more than 10 years old, change them out.
- Brake Caliper & Disc Brake Pads- It is common on vintage Honda's that have sat for a period of time to accrue moisture in the brake caliper. This will cause rust pitting on the brake caliper piston and allow fluid to escape past the rubber seal, which also may be leaking. Calipers are most frequently frozen solid, will expand but not contract or just leak out brake fluid on the disc brake pad. It is safe to assume that all calipers that have sat are in need of a full rebuild which includes replacing: Caliper piston, piston seal, bleeder screw, and fresh brake pads. Speaking of which, brake pads should always be changed out; old brake pads tend to have friction material soaked with old fluid or crumbling from age. When the front brake provides 80% of the stopping power on the motorcycle, brake pads need to be in top condition.
Disc Brake Caliper Rebuild Kit
Early Style Disc Brake Pads (CB450K3 - K4 + CB750K0 -K1)
Late Style Disc Brake Pads (most common style)
- Master Cylinder - This is the other half of the disc brake system, these pieces are kept hydrated by the constant use of the master cylinder with fresh brake fluid. If the motorcycle is left sitting, with or without brake fluid in it, the seals will degrade and need replacing. More often is the case where brake fluid was left in the system, it absorbed moisture over many years and caused excessive corrosion in the aluminum castings of the master cylinder. Bases on the condition of the master cylinder it may be rebuild-able or may need replacement depending on the internal surface finish of the cylinder and / or the fluid reservoir.
Honda CB360 / CB450 / CB550 / CB750 Master Cylinder Rebuild Kit
Complete Replacement Honda Master Cylinder
- Brake Fluid - Over time the brake fluid itself degrades and slowly absorbs water from the air. This happens whether the motorcycle is being used or not. It will impact the braking performance and lower the boiling point of your braking fluid. Depending on how often you ride, this should be changed every 2 years.
Drum Brakes - Just because these do not have many rubber pieces does not mean they are bulletproof. There are a few components we have found to need replacement in the rear drum and front drum brakes as well.
- Drum Brake Shoes - The adhesive that bonds the friction material to the metal shoe linings does not fare well with age. Even if you have plenty of friction material left on the shoe, it is common for the friction material to separate from the shoes causing you to lose all braking power. Front and rear brake shoes are parts that should be changed out for safety.
CB175 / CB200 / SL350 K1 & K2
CB350 / CL350 / SL350 K0
CB360 / CL360 / CJ360
CB450 / CL450 / CB500T
CB500K / CB550
- Drum Brake Cables - These may be salvageable by working fresh oil into the cable, but if there is any fraying or visible rust on the cable strands then it needs to be replaced. The cable can lose its flexibility if it is rusty and cause excessive friction resistance inside the cable housing. The cable could snap when pulling the brake lever very hard while fighting internal friction caused by rust and corrosion.
Electrical & Ignition Components
Battery - Batteries need constant cycling use to stay in good condition. With inactivity, batteries discharged beyond recovery and cannot be simply "recharged" to reactivate them. A typical lead acid batteries have a life span of 12 - 24 months with regular use. However original lead-acid style batteries are old technology and while they still work, a modern AGM (Absorbed Glass Matt) is a better option for the vintage Honda's. They are more stable, last longer without discharge and are compatible with the charging system. An old Honda with a weak battery will display all kinds of strange problems in how the bike runs. A healthy battery is key to a bike that runs well. Lithium ion batteries are not recommended for use with vintage Honda's due to the primitive architecture of the charging system.
Voltage Regulator and Rectifier - The voltage regulator and rectifer are the two key components of your vintage Honda's charging system keeping the battery charged. As mentioned in the battery information, old Honda's like a well charged battery and will display all kinds of running issues with a battery that is not properly charged. Both the factory voltage regulator and rectifer are extremely prone to failure or working intermittently, thus not properly charging the battery. 75% of the time the voltage regulator is the issue, while the other 25% of the time it is the rectifier (FYI bikes built prior to 1970 only have a rectifier). We like to swap the these two individual components for modern single combo regulator + rectifer unit. This is the #1 electrical upgrade / repair that all vintage Honda's need.
Regulator / Rectifier Honda | CB175 / CB200 / CB350 / CB360 / CB450
Regulator / Rectifier Honda | CB500K / CB550 / CB750
Ignition System: Contact Points, Condensers, Coils & Spark Plugs - All Honda motorcycles built prior to 1978, use a points type ignition system (electro - mechanical) to trigger the spark plugs. Points type systems require frequent adjustment, must be clean and all components working properly for the engine to run well. A "Tune up" back in the day was going into this system to replace worn / faulty components and readjust the system so that the engine runs properly. Owing a vintage Honda motorcycle means learning to master the diagnostic and adjustment of the ignition system. Below are the components that will need to be addressed for a well running machine.
- Contact Points: Also known as points, are mechanically triggered electric switch that open and close thousands of times a minute when an engine is running. There job is to fire the ignition coil to generate an electric pulse for the spark plug. Points are a wear item (like tires) and require regular adjustment and replacement after thousands of miles of use. The primary electrical contact surfaces of the points are prone to corrode due to moisture in the air from sitting for years, which means no spark at the plugs. Additionally the rubbing pads of the points are prone to wear beyond use. Even if the parts are in good physical shape, points have to be properly adjusted for an engine to run right. Just because there is spark at the plug, does not mean the spark is occurring at the correct time in the engine cycle.
CB175 / CB200 Ignition Contact Points
CB350 / CB360 Ignition Contact Points
CB450 / CB500T Ignition Contact Points
CB500K / CB550 Ignition Contact Points
- Condensers: Condensers are a type of electrical capacitor used in the ignition system to help absorb and discharge excessive electrical current running through the contact points. Their purpose is to extend the working life of the contact points. Condensers are a wear item as well and should be changed with the contact points during an ignition tune up. A weak or bad condenser will keep an engine from revving properly and cause points to become burnt and wear out pre-maturely.
CB175 / CB200 Ignition Condenser
CB350 / CB360 / CB450 Ignition Condenser
Gemini Ignition Condenser Upgrade
CB550 Ignition Condenser - Coming Soon
- Ignition Coils: Ignition coils generate the spark to the spark plugs. Depending on the engine design there will be one or two coils on the motorcycle. These are another part that we see decay with time. The appearance of yellow wax around the metal ends of the coils are a sign of a failing coil. Often coils fail with use and heat, thus a bike that has gotten back on the road recently that is running old coils may see the coils become intermittent. Bike runs OK for 10 - 15 min, then is dead... and is OK after cooling off. Spark plug boots should be changed out as well.
- Spark Plugs: Spark Plugs or plugs for short, are another wear item. They are inexpensive and easy to replace so just do it. Make sure to set the gap properly and do not over tighten them in the cylinder head.
Oil Change: Gaskets, Seals, Drain Plugs, Oil Filters - At the very least on your vintage Honda motorcycle project, you will want to change the oil, clean out / change the oil filter and perform the basic tune-up procedure. In performing the task it will be necessary to replace the used gaskets and oil seals that you will come across in the process. Paper gaskets can dry out just like rubber and cause leaks around your engine. They also tend to get destroyed when removing an engine cover to access things like the points, oil filter and stator. We have seen plenty of engines where a previous mechanic attempted to re-use an old gasket or substitute by applying big blobs of silicone gasket sealer (RTV silicone) in an attempt to button up the engine without a new gasket. It makes a mess and excessive silicone can break off inside the engine case and clog oil passages (seen it several times). Be sure to have a gasket kit and oil seal kit on hand to replace the paper gaskets, distorted rubber o-rings and oil seals that you will come across. Also we find that sometimes the drain plug on the engine has become stuck or been chewed up by a previous owner when performing an oil change. If the drain plug on your engine is shot, then replace it with a new one.
CB175 / CL175 / SL175 / CB200 / CL200
CB175 / CL175 / SL175 Oil Change Gasket Kit
CB200 / CL200 Oil Change Gasket Kit
CB175 / CL175 / SL175 Oil Seal Kit
CB200 / CL200 Oil Seal Kit
Standard Oil Drain Plug
Black Hole Oil Drain Plug
CB175 / CB200 Tappet Adjustment Wrench
18mm Spark Plug Socket
CB350 / CL350 / SL350
CB360 / CL360 / CJ360
CB450 / CL450 / CB500T
CB500K / CB550 / CB550F
Overhaul Gasket Kit
Oil Seal Kit
Replacement Oil Filter
Replacement Oil Filter Housing Bolt
18mm Spark Plug Socket
Drive Chain - More often than not we find the drive chain on old vintage motorcycles have become heavily rusted and stiff to move. Additionally, it is unknown how an old chain was or was not cared for (typically the latter). Drive chains must to be kept constantly lubricated and coated to protect them from rust and binding. Dive chains are also a wear item that does need periodic adjustment and replacement with use. We find that most drive chains are not kept up with when a motorcycle sits for long periods of time, resulting in a chain with a compromised movement or excessively rusted, thus affecting the chain's strength. Replacing the chain is a safety item, as a neglected chain could snap while while riding the bike. A fresh chain keeps your more expensive front and rear sprockets in good shape as well. We recommend running a high-quality non o-ring solid roller chain as they did back in the '60s and '70s with ample lubrication and regular adjustment.
Suspension & Steering
Front and rear suspension are not often top of the list details when bringing a vintage motorcycle back to life. An out of whack suspension may be worse than just a rough ride; leaky forks with old oil causes the front of the motorcycle to dive at stops, vibrate at speed or lose traction over small bumps. Worn rear shocks will bounce like a pogo stick and cause the rear wheel hop sideways when taking a turn. Loose or catchy steering bearings will dramatically affect the feel of the bike when turning at any speed.
Steering Bearings & Rear Swing Arm - This is another out of sight, out of mind type of part. Most steering bearings have never been service since the motorcycle was new. They are such a critical part of how the bike feels and steers into a corner; they need to be properly lubricated and adjusted. Original steering bearings are of a loose ball bearing design, which are OK to clean and re-use assuming there are no catches or notches in the bearing races and all parts work smoothly. If not, then they should be swapped out for a new set. Tapered roller steering bearings are a nice upgrade over the loose ball bearing style. Give the rear swing arm bushings a shot of grease via the zerk fittings and check for any play or slop along the swing arm pivot bolt.
Front Fork Oil and Oil Seals - Front fork oil is just like engine oil (which most of us are great at changing exactly when it needs it); forks compress often several times a second forcing the oil through tiny passages throughout over and over again. It is important to understand how much action the forks actually see; in fact that Honda specs fork oil to be changed as frequently as the engine oil filter be cleaned, every 6,000 or every year(whichever comes first). The majority of motorcycle projects we come across are also in need of new fork seals because the old rubber seals have dried out from inactivity and age causing any fork oil to leak on the front tire ore front brake (that's not safe).
CB175 / CB200 Standard Fork Seals
CB350 K0-K3 EZ Install Fork Seals
CB350 K4-K5 / CB360 Standard Fork Seals
CB450 / CB550 Standard Fork Seals
Rear Shock Absorbers - The OEM Honda rear shock absorbers are not rebuildable and more often than not, worn out. Even when they were new, the rear shocks were soft and squishy. Just like shocks on a car, they wear out with use. Amazingly, many "restored" motorcycles we have observed are still running the original rear shocks. It is our recommendation to replace the rear shocks with a new set, chosen based on the type of riding you are doing along with the total bike, cargo and rider weight factored together.