How to Restore an Old Junkyard Motorcycle

Introduction: How to Restore an Old Junkyard Motorcycle

About: I always loved making things since I was a kid! I currently make a lot of DIY drones and love 3D printing! I'm also into skateboarding, motorcycles, electronics or anything that can be home made :)

Sometimes, modern motorcycles can be seen as lacking personality, or too modern... what if you want to ride sometime more.. unique? older? that you rebuilt yourself?

Vintage motorcycle are great way to ride something with style, and be proud of riding something you brought back to life yourself!

Plus, they are often an inexpensive way to get a nice reliable bike, and great investments.

In this Instructable, I will teach you how to restore / rebuild an old Motorcycle that is not running, something you can find in Junkyards, old barns, etc.

The example will be base on 1978 Honda CB 750 Four F2 motorcycle I restored.

But first of all, please enjoy the Timelapse rebuild video of the whole process :)

You can watch the details of each step mentioned below in the video ;)

Supplies:

For this project, you actually don't need much:

- A basic toolbox, with wrenches, screwdrivers, sockets, etc.

- Some rebuild parts for the specific Motorcycle model you got, they are easy to find online, most likely, this will be gaskets, seals, etc. Depending of the make and model of your bike, differents websites will have the parts you need. In my case, a classic Honda, I found all the parts I needed on 4into1.com

- Basic motorcycle maintenance fluids: Engine oil, brake fluid, bike cleaner, etc.

- Some motivation :-)

Step 1: Find the Motorcycle to Save

This might make sense, but the very first step is to get the motorcycle for your rebuild project.

There are many places to find such bikes: classic online ads (Craiglist, etc.), which is often the most effective way, junkyards, auction sales, etc.

Old, not restored motorcycle, that has been sitting for years usually retails for very cheap, and you do not take much risk getting one. I do have however few tips when picking an old bike, that might save you some trouble:

- Try looking for a bike that is mostly complete, bike with missing parts, especially engine parts can cost you some money and trouble down the road when looking for those specific parts that might not be easy to find.

- Prefer bikes that weren't put out of use because a big crash, this is easy to tell, just look if the major chassis components (wheels, fork, frame, etc.) are straight and not damaged.

- A bike with a title is often better, but depending on your country, you can sometimes get title for old classic motorcycle fairly easily if you have a certificate of purchase.

- Choose a bike with an engine that is not seized!! this is really important if you want to save yourself a lot of trouble from repairing a seized engine. Telling if the engine is seized is very simple: most older, classic bikes have kick starters, you need to be able to kick start/move the kick start lever freely. If the bike does not have a kick start. Just put it in gear, and try pushing it, it should be difficult but you should be able to crank the engine and feel the pistons moving while pushing. If nothing moves at all and the rear wheel slides on the ground, then it's bad sign.

- Other than that, just choose a bike that you like and fit the style you are looking for, whether you want to keep it original or make it a cafe racer (see my other Instructable for that). Older bikes from the 70's like classic Hondas or Yamaha often have breaker points ignitions which are easier to rebuild.

The bike I found for this project was a 1978 Honda CB 750 Four F2, I found it in a junkyard. This bike only had 1 owner before!! and sat for more than 20 years, probably even more than 30 years!

Overall, it was in great shape. It was not running obviously, and had flat tires you couldn't even roll, but it looked great and was complete.

The first thing I did after getting this bike, and I highly recommend that you do the same with any bike, is to wash it thoroughly, that way I can remove 30 years of dust and get a good look of the overall state of the bike.

Then, you can literally find service manuals for any motorcycle, even 70s motorcycles, you can sometimes find them for free online, or you can buy one for around $30.

I highly recommend that the first thing you buy for your project is a service manual, this will be your best friend during the rebuild.

Step 2: Restart the Engine

Now that we have an old motorcycle for our project, the first step, and probably the biggest, is to get its engine running again!

When trying to restart an engine that has been sitting for year, it is important to take the time to do the basic maintenance and not rush into trying to start it. It is best to rebuild/fix what needs to be fixed, before trying to start it and probably cause damaged.

What does an engine needs to run? well it needs some fuel, an air/fuel mixture to be exact, it needs some sparks, and it needs to be in good shape and well lubricated.

So, most of the time, you'll have to do 3 steps before starting the engine :

- Rebuild the carburetor (and change the air filter), because old fuel sitting for years often creates varnish and gum that plug all kind of tiny holes and jets in the carburetor. Plus, the seals will most likely be too old and cracked.

- Check or rebuild the ignition system, and more importantly check that static timing is set correctly.

- Flush the old engine oil, change the oil filter, and pour some new fresh oil inside, never try to start with an old motorcycle oil that has been in there fore years. You can also lightly check the pistons and cylinder walls from the spark plug hole with a torch light or endoscope. Then do a compression test.

In addition, you'll also need to check the condition of the fuel tank and fuel lines, most likely, the fuel might be rusted inside and will need to be treated with a rust remover, then an epoxy resin based sealant before it can be used again. So it is a good idea to do the first start of the bike from an auxiliary fuel supply line.

In my case, this is what I did on my bike:

Carburetor rebuild

Even if the carbs were in great shape and the slides were moving freely, I wanted to do a full rebuild anyway, and when disassembling the carburetors, the bowls and jets were full of a very thick gum and varnish from the old fuel. So I took the carburetors completely apart, cleaned everything in my ultrasonic cleaner. The ultrasonic cleaner is VERY effective for cleaning carburetor and removing varnish and gum, especially in some hole and ports.

Then, I laid everything on a table, and started re-assembling them again, using new carburetor rebuild kits with new seals, o-rings, gaskets, jets, etc.

A carburetor rebuild is not as difficult as it sounds, and every bike, even old bikes from the 70s will have a step by step on how to do this on its service manual.

New ignition system

Older bike will most likely have breaker points style ignition, and breaker points can corrode and become faulty over time, especially if the bike has been sitting for a long time. Moreover, new breaker points and condensers are very cheap! So I did not hesitate, and did not even tried the old breaker points and installed new condensers and breaker points.

Plus, I took this opportunity to adjust the static timing of the bike, the static timing means when you tell each cylinder to fire, it is basically the timing of the spark. This is very easy to adjust, all you need is a 12V inspection bulb, I've made a very simple homemade one with a 12v LED, with two crocodile clips at both end. You just need to plug the positive side of the LED on the breaker point, and the negative side on the frame. Then, when turning the engine over, you will notice that the LED will light up at the certain point. Adjusting the timing is basically making sure that the the LED lights up when a mark, on a crankshaft is aligned with another mark on the engine. If the LED lights up before or after the mark, you just need to turn the breaker point a little bit. It is that simple :)

The rest of my ignition system was fine, but it is good idea to check the coils, spark plug, and spark plug wires as well.

Oh, and of course, to do everything mentioned above, you need to have a good, charged battery on your bike. So for an old bike, you'll most likely have to change the battery first.

New fluids and filters

When restarting an engine after a long time, always drain the old oil and change the oil filter, this doesn't cost a lot and is a lot better than have it running on old oil that might have loose its lubrication property.

What I like to do is this: I change the oil with some cheap, generic engine oil, then when restarting the bike, I run it for 15 minutes on that oil. Then I drain the oil again, and finally fill it up again with, this time, some good quality and more expensive oil from famous brands.

Doing 2 oils changes in a row is a great way to flush the engine and crankcase.

On my project, I also removed the oil pan from the bottom of the engine to clean it better, and to inspect and clean the oil filter screen located on the bottom of the crankcase.

Step 3: Restore the Suspension & Wheels

Getting the engine of an old junkyard bike running is one thing (yet probably the most difficult one), but getting it to ride well is another!

If you plan on riding a very old motorcycle, you absolutely need to check (and most likely change) some key components like the wheels, suspension and braking system.

Let's focus on the Wheels & suspension here first.

If the motorcycle you got has not been ride in years, there is 90 % chance that the tires will need to be changed. Tire rubber loose its property over time, it becomes harder, and is most likely to crack and slip. It is not recommend to ride a tire that is more than 6 or 7 years old, even if it still in good shape and not worn down. Riding with old tire can be very dangerous, I know someone who did this mistake with an old junkyard bike, his wheels started sliding in a turn and he ended up in a bad crash.

Thankfully, there is an easy way to read the age of the tires! Every tire has its manufacturing date engraved on its sides. Look for a 4 digit number in a oval circle. The first 2 digit will be the week the tire was made (from 01 to 52) and the last two digits is the year it was made. For example, "4215" means that the tire was made on week 42 of the year 2015.

If there is only 3 digits, then the tire was made before the 2000s and absolutely need to be changed.

So, point is, you'll probably have to get yourself a new set of tires.

Depending of your motorcycle, you might have tubeless or tube type tires, if you have tube tires, then get some new tubes as well, they are fairly cheap and it is always best to start with new, fresh tubes when changing tires.

You'll also want to check your wheels, look for bents or cracks around the wheel, and check if they are straight.

An easy way to check if a wheel is straight is just by lifting the bike, and turning the wheels, then you can just look by eye if it is rolling straight, or you can also place an object very close to the wheel, and check if the gap between the wheel is always the same all around.

If your wheel is not straight and have spoke, you might be able to adjust this be adjusting the spokes. If your wheel is not a spoke type, then you most likely will need to look for new wheels.

On my CB 750 Four, I had to change both the wheels and tires.

Regarding the suspensions, you'll need to check both the fork and rear shock.

For the fork, best thing is to change the fork oil, information about the quantity and recommended viscosity can be found on the service manual of your bike. This is pretty easy to do, each fork and bike will be different, but most of the time, you have a drain plug on the bottom of the fork and a filling cap on the top, to drain the oil, just open both of them and pump the fork, then close the drain hole, and fill back with fresh oil.

You'll also want to inspect the Fork seals, you need to make sure that they are in good shape and not leaking, this is easy to do, just check the fork tube right above the fork seal with your finger, there shouldn't be any oil on the tube. If there is oil, then the fork seal is leaking and need to be changed.

For the rear shock, the easiest way to inspect them is by eye (looking for oil leaks, cracks) and by testing it (pushing on the rear of the bike and checking if it is working properly, with good damping and rebound).

On my CB 750 Four, one of the 2 rear shock was missing, and they were not looking good, so I decided to install 2 new shocks. Replacement shocks are not very expensive, especially for old classic Honda Bikes.

Step 4: Restore the Braking System

It's one thing to get a motorcycle to move, it's another to get it to stop!

If there is one single component you absolutely need to check and restore on an old bike, its the braking system. There is nothing more dangerous than a faulty braking system.

Thankfully, braking systems on older bike without ABS are pretty easy to restore.

You'll most likely have either Drum brakes, or hydraulic disk brakes.

Let's start with the easy one: drum brakes.

It is very easy to check if drum brake are working properly: just try them while pushing the bike, most of the time, you'll only nee to adjust the rod to increase or decrease braking power while stepping on the brake pedal or pulling the brake lever.

However, even if the bike seems to brake well, always remove the wheel and the drum brake from it, to check the brake shoes, check if there is still enough braking materiel, and if the brake shoes and drum is clean. It is always a good idea to wipe everything clean with some brake cleaner.

Now, if you have disc brake, there is a little more thing to check:

First of all, check the brake pads, brake pads are very cheap and I like to replace mine even if the old brake pads are still good.

You'll also need to change the brake fluid, brake fluid needs to be changed every 3 years, or it'll loose its properties. So bleeding the brake with new brake fluid has to be on your to do list anyway.

But before doing so, check all the brake lines, master cylinder and caliper for leaks and cracks. Most of the old bike have rubber brake lines that will most likely be cracked. I like to replace my brake line with brand new stainless steel braided brake lines before bleeding the braking system.

You also need to check if the piston is moving freely on the calipers, this can be done by removing the pads, thein trying to push back the piston inside the caliper.

I have another Instructable detailing how to replace brake lines and easily bleed brake, so make sure to check it out ;)

On my CB 750 Four I changed all the brake pads and brake lines with some brand new stainless steel braided lines. The old master cylinder were also damaged (seals damaged, corrosion, etc.) so I decided to install brand new, modern, NISSIN master cylinder.

If you need to change your master cylinder, ALWAYS go for some famous brand (Nissin, Brembo, etc.) and always avoid cheap Chinese master cylinders. Master cylinder are a vital component of the braking system and you don't want them to fail when riding at 100 kph!

Cheap master cylinder tends to leak and fail under pressure.

I then bled the brake with new DOT4 brake fluid and I was good to go!

Step 5: Check and Restore the Clutch & Transmission

This step may not be required on every bike, but if something is wrong, you'll notice it right away.

The goal here is to check if the clutch & drive train are working properly. Regarding the final drive, most motorcycle have chains & sprockets, and it is pretty easy to determine if they need to be changed. Just check the chain: it should be rust free, without any kinks or "hard spots", and check the sprockets: the teeth should be round, not pointy. If the teeth are sharp and pointy, then they are worn down and you'll need to replace the chain & sprockets.

On my CB 750 Four, the chain & sprockets were fine!

Then, you need to test the clutch, this is very simple: just test ride the bike, you'll quickly notice if the clutch is slipping or has a problem.

Mine had a problem: the clutch friction disks were stuck! this happens sometimes when a bike doesn't run in a very long period, like more than 10 or 20 years. You can tell that the clutch is stuck when nothing happens when pulling the clutch lever: the discs don't disengage and if you put it in gear, it will stall.

So I took my clutch apart, and I also notice that a bit of the clutch pressure plate was broken, a very common issue on CB 750 Four bikes.

So I went ahead and installed a new clutch pressure plate, new clutch discs, friction discs, and springs! so my clutch was brand new, and the first test ride after this came out perfect!

Step 6: Restore the Electrical System

Depending on the condition of the motorcycle, this might not be necessary.

By Electrical System, I mean all the lights, turn signals, horn, indicators of the bike, not the ignition system which we described and already restored earlier.

Restoring the electrical system is not really a difficult task, but it can take some time if you have some issue like a faulty wiring harness. Overall, you want to make sure that everything is working well: headlight, turn signals, horn, dashboard bulbs, etc. and that you are not frying any fuse which could mean that there is a short circuit somewhere in the harness.

Most of the time, the only thing you'll have to do is change a light bulb, or change a broken turn signal, etc. Sometime, on some other bike I noticed that the left turn signal wasn't working for instance, and upon inspection, I noticed that the wire from the left turn signal switch was broken, so the only thing I had to do was solder it back into place.

On my CB 750 Four, here are the things I did:

All the turn signals were missing because the previous owner removed all of them, most likely to save weight while riding on a race track. So I got 4 new, small yet vintage style turn signals that I installed back on the bike. Aside from this, everything was working well.

Oh and of course, I changed the battery with a new one! Any motorcycle that has not been run in more than year will need a new battery anyway. Except if the battery was unplugged and store in a good condition. But any battery left plugged in that long would have discharged to a point were it will never recover as before.

Step 7: Make It Look Great Again (cosmetics)

Now, the final step!

You got yourself a nice old junkyard bike, you got it running and riding well again! All you have to do now is make it look good again.

There are a tons of ways to do so, and it is up to personal tastes. You can either keep it original, by trying to find new replacement parts or you can make it a cafe racer (you can check my other Instructables for more info on that topic).

I use to make cafe racers out of older bike I get like this one.

However, upon cleaning, I noticed that this one was in a really good condition overall, and that it would be sad to modify it into a cafe racer or scrambler, so I decided to keep it original and restore it with to the original design (with few tweaks).

I managed to found brand new replacement side covers, and a red paint that matched exactly the rest of the bike.

Regarding the chromes, I cleaned and polished all of them with some steel wool and they came out amazing! they seemed like new!

I still have some few minor adjustments to do to the bike like change the seat cover, but overall, I'm pretty happy with the looks of it!

Step 8: Enjoy Your New (old) Bike!

And here we go!

Our vintage motorcycle is restored and ready for a nice sunny ride! :-)

I love riding vintage bikes, everything is so simple about them, and they have character, you can feel their engine roaring and it is up to you to learn the power band and how to get the most of out them!

I hope that this Instructables will encourage you to start a restoration project, vintage motorcycles are awesome and it would be nice to see more of them on the roads rather than sitting in junkyards.

Remember to always be safe when riding: always wear full protective gear (helmet, gloves, long-sleeve jacket & jeans, etc.) even when it is hot out there, and most importantly, always ride within your abilities.

We are living though times with half of the world being on lockdown right now but hopefully better times will arrive and we'll be able to enjoy riding on sunny, twisted roads again!

Ride safe ;-)

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    29 Comments

    3
    tytower
    tytower

    11 months ago

    Seems like a very thorough treatment of how to approach it . May I suggest an important improvement that is applicable to restarting all engines that have sat unused for more than a few weeks.

    The cylinder bores get surface rust on them quickly because they are normally left highly polished by the movement. Some oil remains when it stops but not for long.

    Before you turn it over , take the spark plugs or injectors out and pour a cup full of diesel into each cylinder. Let it soak through for a couple of days then carefully free the motor up and turn it over with a spanner in the direction it runs . Once free do the diesel thing again and keep turning it over.

    If you neglect this the rings will contact the rust and clog or break them and when running the piston and bore wear will be noticeably greater. The better way to avoid this is to pull the sump off and use some emery paper on the lower rusted cylinder bores.

    0
    whatacharacter
    whatacharacter

    Reply 11 months ago

    I use marvel mystery oil instead since it is both an oil and fuel additive, this I use for engines that crank over and have been sitting for a long time before I even try to start it. Unless the engine is completely seized which in that case it's probably a gonner then use whatever you want but it probably won't bring it back to life. A rebuild would be a better option. For me personally I wouldn't fill my engine up with diesel fuel and seep loose rust particles into the crank case. Not saying you're wrong or right, just my opinion.

    0
    tytower
    tytower

    Reply 11 months ago

    Of course its always better to pull down and rebuild if you know how and can afford the cost and time. Ive done a few old tractors with the diesel method and a landrover. Clearly though when using diesel it can be a huge saving and the old oil with the diesel or rust or anything else will naturally be changed before the engine is run won't it .

    0
    jwdrewadsk
    jwdrewadsk

    Reply 11 months ago

    So glad you mentioned this! It's easy to get excited about firing up an engine for the first time in years and skipping critical steps like this.

    This is a good checklist to have on hand for an engine that is not seized:
    http://www.kaiserbill.com/Web-PDF/Start-Up.pdf

    0
    tahitianrider
    tahitianrider

    Reply 11 months ago

    This is a very important step indeed, that I forgot to mention. What I usually do, is as soon as I buy and pick up the bike, I remove all spark plugs and spray some Fogging oil inside each cylinder, waiting for the restart.

    0
    gbeutler
    gbeutler

    Reply 11 months ago

    So all told. 1. How many hrs of work
    2. Total investment ij new parts?
    3. Purchase price of old bike
    4. Bikes to look for. I like Honda too

    0
    mrcurlywhirly
    mrcurlywhirly

    11 months ago

    Nice instructable, well presented and excellent work! I guess the one thing I would add is - start by looking for a bike you would really love to own and ride, not a cheap junker, as this can quickly escalate into an expensive process. My last rebuild was an SRX250 for my partner, that was a complete basket case - fuel tank leaking, front brakes screwed, front forks leaking... and plenty of cosmetic damage. Even a simple single cylinder 250 can hemorrhage cash quite quickly, but the end result was well worth it, and there is an added feeling of accomplishment when you know a machine inside out.
    BTW - I am interested to know how much the CB has cost to rebuild in parts?

    0
    datoo786
    datoo786

    11 months ago

    Wonder what camera have you used? A go pro? What accessories with it? The recording is very good and so so so stable!!

    1
    barrelgazer
    barrelgazer

    11 months ago

    Wonderful wonderful. I have a restored 1976 Jawa 350 ( yes Jawa) after doing all the work, like you, it is “my bike”. Only real issues I had other than getting parts from a now non-existant country, Czechoslovakia, was insurance. Because of its age I could not get regular insurance and had to go to a vintage vehicle insurance company.
    The Jawa now runs on Chevrolet points. LED bulbs really added lumens while using less power. The electric systems in old USSR vehicles were really arcane compared to modern designs but that is all part of the fun in an old restore.
    I hope you do another.

    0
    CharlieR18
    CharlieR18

    11 months ago

    A CB750 Four? That's not so much a junkyard bike as an orphaned collectors' item. I haven't known of one of those to go to waste. They are in demand. As someone else commented, it would have been fitting for a how to, to include the before pictures.
    I have included before and after of my 1979 Yamaha 750XS Special. I knew absolutely nothing about working on motorcycles when I dragged that on to a trailer and stuffed it through a doorway into an in-house hobby room. It spent the previous 7 years left out in a garden like an old rake. Often I wondered what I thought I was doing it for, but the end result was very satisfying.

    XS750 before after.jpg
    0
    JerryL1206
    JerryL1206

    Reply 11 months ago

    The pics at the beginning of the post (step 1) are the before pics. Also watch the video. Starts out with the before.

    1
    KJL316
    KJL316

    Tip 11 months ago on Step 1

    I did this with my father's 1978 Suzuki GS550 after it sat in his garage for almost 20 years. All good advice except I would add get a Haynes or Clymer manual for your bike, it was invaluable for me. Also, odds are there is a forum on the net that discusses the make and model of your chosen restoration bike where you will find all sorts of information and help. Lastly, I'm sure there are many sources for parts but Ebay was my go to source for used exact replacement parts as well as new parts.

    0
    1234567guy
    1234567guy

    Question 11 months ago

    What happens if the parts don't sell anymore.
    Like for example like an old bolt that can't be manufactured anymore.

    0
    tahitianrider
    tahitianrider

    Reply 11 months ago

    I have worked on about 6 old bikes, and this never happened. You can always find replacement parts. A bolt for example, it is very easy to find replacement bolt made to the size needed. I never buy original bolts, only new bolts from a specialized bolt store. A most of the parts of old bike (clutches, carbs seals, pistons, etc.) can still be found as new replacement (not OEM but aftermarket). And if even this is not enough, I sometimes just search for used parts online in good condition

    0
    ljhtg
    ljhtg

    11 months ago

    No before shots! Would be nice for comparison.

    0
    JerryL1206
    JerryL1206

    Reply 11 months ago

    I think he’s saying that the pics at the beginning of the post (step 1) are the ‘before’ pics.
    ???

    0
    obillo
    obillo

    11 months ago on Introduction

    Truly fine ible--you've got me dreaming again. I'll be looking for something older, say a British 2-cyl, sit-up-straight model or an old BMW of mid-60s vintage. Modern bikes haven't appealed to me esthetically for decades.

    0
    tahitianrider
    tahitianrider

    Reply 11 months ago

    Thanks! glad this motivates you :)
    Yeah I'd love to have one of those older bike as well, but they are too difficult to find

    1
    rgerber1
    rgerber1

    11 months ago on Introduction

    great job, if memory serves me, the CB750 was the fastest production bike at the time it came out, in later years I had a CB900 which was the punched out 750 but with a jack transmission and a goldwing 1000 rear end, the tranny had a high low setting ( 5 x 2 gears ) cuz the driveshaft was on right side and engine output left side, was a fun bike... Enjoy yours..

    0
    Mantree91
    Mantree91

    Reply 11 months ago

    It was untell the early 70s. That said they are wicked fast for a bike of the era. I ride a 74 and it is a blast but it has its quarks especially in transmission gear spacing.