Restoring a 1997 Honda CB400 | Full Motorcycle Restoration

On March 11th, 2023, after I resigned from my job in Kizilsu, I picked up another project. It was a 1997 Honda CP400. At first glance, the bike looked fairly complete, but it could not handle close inspection. The exhaust was badly rusted, the engine had serious oil leaks, and the rear wiring was exposed. Messy and disorganized, I removed the rear seat, and the cover fell apart instantly. The fuel tank was not in good shape either. With at least five layers of paint on it, the rear body panels were tied on with wire, and once pulled off, they were glued inside. But for us, this was not a big deal. The real problem was that water came out from inside the engine, which made me think the engine was most likely finished. Put on your gloves and let's start fixing it from the beginning. I finally managed to pull off this rusted seized chain. Back when I was 17 or 18, I could easily lift and remove a 100 plus kilo engine by myself. But now, I need extra tools to help, and the condition of this engine is really not good at all. I just hope when we repair it together, it does not give us too many unexpected problems. Once this front brace was removed, the bike was completely stripped, so we decided to start from the front wheel and work our way back after removing the tire. The front wheel hub was still in very good condition, and the front brake disc was excellent and still shiny, but the rear wheel was badly repaired to the point that I seriously doubted they came from the same bike. I removed both brake discs and placed them aside, then thoroughly cleaned the surface of both wheel hubs after sandblasting the front and rear wheels returned to their original aluminum color with a very solid texture. Without waiting, I immediately sprayed an anti-oxidation primer to prevent corrosion, then applied a dark gold factory matched color, and finally sent them into the paint baking room for high temperature curing. I used a simple old school method to make sure the valve seal did not leak, then used an iron rod to knock out the bearings on both sides of the wheel, cleaned away all the old rust and debris, and pressed in brand new bearings to put everything back in place. Now both the front and rear wheels are basically cleaned up and sorted, but according to the factory service manual, they still need proper wheel balancing. Unfortunately, I do not have the professional equipment for that, but it is not a problem because I can still find a way to handle it. Even though I used European standard touring parts, they were not a perfect match, but to make the base more stable, it did not really matter. I know a few practical tricks, so I reopened the mounting, adjusted it, and tightened everything back on, and that solved the problem. After installing the bearing and mounting the laser tool, the wheel balancing setup was complete. It is essentially a stable level stand that allows the wheel to spin extremely smoothly with almost no resistance, so the wheel can rotate freely and naturally until gravity helps reveal the true lowest point, making it easier to understand the balance condition of the wheel before adding any correction weights. Then small, 5 gram weights are added gradually, until the wheel can stop freely at any position that is the whole principle, and the result is very stable and accurate. After finishing the wheel, Balancing Our Garage now has another dedicated tool which will be useful for many future projects. Then we moved on to working on the frame. This frame is also from 1997, and after so many years, it only had some paint peeling with no rust at all, which really shows the quality of the materials Honda used back then. I followed my usual method and put the frame into the sandblaster to remove all surface dirt and old residue after cleaning the frame. The serial number starting with NC31 became clearly visible, proving it was still original. Then I applied an epoxy primer, followed by pearl black paint, and finally cured everything with high temperature baking to fully lock in the finish. This is his rear panel. It is hard to tell how this hole even got there. I first removed all the damaged surface material, then set up the welding machine on AC mode. I put on my welding hood, you put on your dark glasses, and together we carefully filled in the hole, welding it back to restore the panel as best as possible. With the hole welded, the rear panel is fixed, and the surrounding parts can be realigned and reassembled properly. This is his engine, and it can truly be described as completely filthy. Put on your protective hood, because we are about to get to work, and this job is tricky and challenging. As soon as I drained the engine oil, my brand new gloves were covered in grime and sludge. It is already a nightmare, but the problems did not stop there. When I removed the oil cap, I found metal shavings and fragments inside, which is a very bad sign. And as I continued unscrewing the third bolt, even more metal debris fell out, showing just how badly damaged and worn this engine is. Wow, we've really hit the jackpot. They've even managed to build this structure on top like this. Please forgive me if my words are not very precise. I cannot accurately describe how I feel right now. This engine is already severely corroded. The area next to the middle cylinder, where the coolant sits, is completely filled with debris and impurities. All of this damage was caused by the tap water that was added into the engine over time. Now, I have fully disassembled this engine, and its biggest problem is the severe wear on the small parts of the connecting rods. Three out of four bearings are badly worn, which is the result of insufficient engine oil lubrication. Fortunately, the engine cylinder walls and crankshaft are still fine, but the cylinder head has a total of 16 valves, and 13 of them do not close properly, which means the next steps are going to be very challenging. Put on your rubber gloves, because we are going to thoroughly clean every single internal part of the engine to remove all debris sludge and old oil buildup. But this engine has so many internal parts, I am not sure if we can put them all back together correctly. This is the cylinder head, and you can clearly see the sleeves and the heavy carbon buildup inside. There is far too much for simple brushing to work, so it looks like we are going to need to use some serious force to deal with it properly. I used a dry ice cleaning machine to thoroughly clean all the valve areas, and now everything is super clean. The cylinder head was then polished with 3000 grit sandpaper, leaving only minor pits that are negligible and do not affect use. All the engine parts are now laid out neatly by size. Fortunately, there are not many parts that need replacement, but the original parts are extremely expensive. I replaced the piston kit, and the connecting rod bearings. Now put on your gloves and protective gear, because we are about to start reassembling the engine. Don't forget to like, share and subscribe, and hit the bell icon to stay updated with our latest videos. I don't think it's a big problem that the screw is 0.9 mm too big. After installing the connecting rod, the engine is now almost complete. A little over one third of the work is done next. We need to clean the cylinder head valves that are not sealing properly. I first used the machine tool to remove rust from each valve, and then carefully worked on each one individually to ensure proper seating and function. This engine is now fully assembled, and as you said, it was not too difficult. But looking at the exterior, there is oxidation and peeling paint, and in some areas the paint has even been scraped off. It seems we still need to do some sanding and repainting to restore the surface, so keep your eyes protected, because I am going to handle this part of the work. You can open your eyes. Now this is the original color of the engine. It's white, with a really nice texture. Next, we follow the usual process, first applying a high-temperature resistant epoxy primer, then spraying a matte top coat, and finally curing it at high temperature to fully set and protect the finish. At this point, the 1997 Honda CB400 engine has been fully restored, and looks like new, giving a huge sense of accomplishment. It can now be reunited with its old sister bikes, and even the adjustable maintenance platform underneath, which allows it to be lifted and positioned freely, was something I built myself during the winter of 2024, specifically to work on this bike. OK, done. The panels and frame of this maintenance platform were all made from 6 to 8 mm carbon steel plates, costing me several hundred for all of them. For the leg connections, I cut 30 thick iron plates drilled holes, and fitted them like durable bushings, then put on your protective glasses, because I am going to weld everything back together to finish the platform. The leg connections were made from 10 mm thick carbon steel plates as a single piece. The central connecting plate was cut from a 160 mm square steel stock, and the other connecting shaft was made from a solid 35 mm carbon steel rod, honestly, because I could not calculate all the forces and stresses, I just used heavy materials everywhere, to build it strong and sturdy. After installing this panel, the main frame of the lift is complete next. We follow the usual process, first spraying a layer of epoxy primer to prevent rust, and finally finishing it with your favorite green color to complete the lift, and make it both strong and visually appealing. Next, we can install the hydraulic system and the quick repair mechanism, then add the labels, and it ends up looking and functioning just like a product made in a professional factory, with all the details and finishing touches in place. The best part is that it can now lift and lower freely, using just its battery, without being limited by a power cord. And now we can finally reunite it with its old sister bikes, making everything fully functional and ready for use. The chassis is now almost fully assembled, only the troublesome fuel tank is left. I heat it up with a heat gun, while prying off the old paint with a scraper peeling away layers. Three or more thick, the tank has no major rust on the surface, just a lot of small dents, but it's not a problem, I can carefully work on each dent and gradually smooth them out. This is the fuel tank, after all the dents were carefully removed, and now for the finishing, since the surface color is pearl red, I applied four to five even coats to achieve a smooth and vibrant finish. Finally, attach the high-quality one to one replica Honda emblem, and you can install it on the bike. I removed the old crumbling seat cover and wrapped it with a new one. At this point I had, working bit by bit, fully restored the entire bike from top to bottom, according to the original factory standards, and now we can finally try to start it, don't forget to like, share and subscribe, and hit the bell icon to stay updated with our latest videos. It can now start perfectly with a smooth idle and the classic CB engine sound is still alive and well. Now we are ready to take it out for a test ride and see how it performs on the road. Back when I was 18 or 19, anyone who could ride a four-cylinder bike could easily make me jealous, and this bike in particular was beyond imagination. It was first introduced when only small bikes were common. It was hailed as a legendary machine, the indestructible CB, alongside other bikes of the era that were notorious for breaking down. Now the CP400 has reached its 6th generation, yet unfortunately it still hasn't been officially introduced here in the country, and so this 1997 Honda CP400 has finally been fully restored. Thanks for all your help, wishing you health and prosperity.