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1982 CB450 Nighthawk Project

7964 Views 50 Replies 11 Participants Last post by  Parry
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Hi guys, I'm new to this community and i thought id share my build/ project with you all. This is my first project and I'm not very experienced but i think i can learn.

On June 5th i bought a 1982 CB450 Nighthawk that was in Non running condition sitting outside for months. the previous owner said it suddenly stopped working and that it leaks oil from the oil drain plug. His ad listing was $600 but upon inspection it looked like it was in really really bad shape with surface rust and somewhat high KM of 66000 Kilometers. upon discussion he just really wanted to get rid of it for space so he said $100 and i couldn't pass it up. So this is the story of my $100 CB450 project. Strapped on the back of my suv and i took her home.

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I bought the bike at night so i didnt have a good look, In the morning i discovered it was leaking pretty bad and had lots of rust and that tank was in bad shape.

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So my first objective was to get it in running order, it took me about 1 hour to diagnose a faulty solenoid, i used a wire to bypass it and she started easy first time.


my next objective was to fully strip the bike to the frame, this is my first time doing this so i took my time in labeling everything and putting the parts i didn't need into a box. took me about 8 hours till it was done.

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I ordered a seat i liked online along with a new solenoid, while i wait for those I started working on the tank, I have fully stripped the paint but when i looked inside the tank it was full of rust.

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I have bought Metal rescue rust remover (water based) and its currently getting rid of that rust, while i wait for that, i thought id look at the engine leaking oil problem. upon inspection the previous owner has a poor job JB weld on it. after removing it this is what i found.

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so this is where i kind of didn't know what to do... i was looking at option to get it welded but it was so expensive. The next best thing is to use a piggyback oil drain plug, so i bought a plug for $10 and i am going to jb weld it on to the engine. this way the plug will never move and i have a new oil drain. hopefully it works.

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I scuff up the surface and completely clean it of all oils and grease, than i apply the JB weld. i think it turned out pretty good, its a nice even thick layer.

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This brings me to my current status of my project. I am waiting for the rust to clear from the tank before i bondo the dents and paint, i am waiting for my seat to come in before i decide to cut my frame.
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Nice project, looks similar to my own Nighthawk 450 project (see my signature for the link), but at least you have all the parts! How is the rest of the bike? Forks not leaking? Brakes ok?

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Welcome to the group.

Here's some light reading you may find useful:

http://www.hondatwins.net/forums/67...n/16105-basic-checklist-new-you-old-bike.html
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UPDATE:

So the metal rescue was a bit of a let down, over 2 days and there is still mild rust. i think its because the tanks has oil / gas residue which prevents the water base rust cleaner from working well. So plan B, is to use Muriatic acid. this stuff is not fun to handle, make sure you have all the proper safety equipment.

Water Product Liquid Fluid Plastic bottle


Now i got all of the rust out but i was having an issue with flash rusting. i'm just going to leave it as is for now and deal with the rust a little later.

Now i want to focus on getting the dents your of my tank so i use bondo and sand it down to smooth, after sanding was complete in cleaned the tank up and hanged it for a filer primer.

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Primer looks ok, but i did notice some pinholes in the paint where the bondo was, i was hoping the filler primer would cover it but it didn't work. my next step will be to use a glazing putty to fill those holes. i will leave the tank in primer stage until the project is moved ahead more since i am probably gonna be touching it alot and i dont want to ruin the finished product.
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Welcome to the forum. Great to see another 400 series here.
Welcome aboard.
Before you go any further on the tank take it to a radiator shop to have it pressure tested. These particular tanks are known for rotting out in the lower rear corners, that's why they're so hard to find. I had a tank that seemed good and when tested all 15 pinholes showed up. $175 later the tank was repaired, cleaned and professionally lined.
I'd suggest replacing the lower case as a permanent repair, fairly easy now that the engine is out. Just remove the clutch, stator and shift rod, flip the engine upside down and remove bolts
Welcome aboard.
Before you go any further on the tank take it to a radiator shop to have it pressure tested. These particular tanks are known for rotting out in the lower rear corners, that's why they're so hard to find. I had a tank that seemed good and when tested all 15 pinholes showed up. $175 later the tank was repaired, cleaned and professionally lined.
The tank looks like its had some work done to it already underneath, it has alot of welding and weird bumps. it does hold liquid in it without leaking so i don't think im going to test it. I really trying to stay on a budget for this build.

I'd suggest replacing the lower case as a permanent repair, fairly easy now that the engine is out. Just remove the clutch, stator and shift rod, flip the engine upside down and remove bolts
If my JB weld does not hold, i am going to change the case for sure. Ive already been looking on ebay for one. I don't mind having to take the engine back out if i have too.
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Update:

So my seat arrived today, I put some parts back on to test fit it and to see how the bike looks. My next goal is to cut the rear frame to fit the seat better. Initially i wanted to add a U bar behind the seat but i don't know how to weld or have the tools for it so I'm just going to improvise something in the future.

After i have the perfect fitment of the seat ill start to sand my frame, cut off all the useless metal i don't need and ill apply primer.


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I know it kind of looks ugly in its current stage but that's because everything is not painted yet, a lot of parts are getting blacked out, the forks, the engine, the wheels. My tank will be white though.

I'm taking inspiration from this bike below, i like the white tank brown seat look. hopeful it turns out nice.

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UPDATE:

Its been awhile since my last update. Making slow progress

First i started by cutting off the excess rear frame so that the seat would fit and look better. I plan on covering the holes up in the future

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Next i start to cut off and smooth out all the tabs i don't need. took me a while to learn how to use a grinder properly. I used a wire wheel to give it a smooth look.

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At this point i start to get all the old paint off the frame so i can get it preped for painting in the future, im still not fully done getting all the old paint and rust off.

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I turn my attention to the rear suspension , Originally i was thinking of just buying new black rear suspension but i decide to paint them and see how it goes. they game out really good.

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After finishing the rear i took a look at the ugly front forks and painted them black as well. Came out really nice and clean.

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So the suspension parts are finished. I turn my attention into making a Electronics Bay/ battery holder box under the seat. I use sheet metal for this and i have come up with a decent start. its not perfect but still working on it.

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My current goals are to finish the electronic box, get the frame painted black.

I'm also searching for a small and light battery that's not to expensive. If you guys know of any please let me know.
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Nice work going on there. Small lightweight battery? You're talking about the lithium based ones to fit those specs. Specific issues with those batteries are the overcharge rate and heat. The batteries need air circulation to keep cool. Then there's the charging rate. This model series charges at 15V +/- .5V so hitting 15.5V is not unheard of. The lithium batteries don't want to see more than @14.2V, they tend to burn out and in some cases catch fire. The cure is to upgrade the regulator to a Mosfet type regulator, FH020AA is a popular one and there's an upgrade to that SH847. Not cheap though Home
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UPDATE:

Been a while since i last worked on the bike since i needed help with Welding. anyways, i got a friend to weld sheet metal to cover those holes i made when cutting the frame

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The sheet metal was a bit thin and made some holes, so i used bondo to cover it, sanded it down and it came out pretty nice.

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Ok so now my frame is essentially ready to paint, i clean it up as much as i can and i use a self etching primer as the first couple of layers

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Next step was to use a sealer primer and i got everything into a nice even gray color

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Lastly i used about 2 cans of black paint and than to finish it off 2 layers of clear coat, in the end it came out really nice

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My next steps are probably going to be painting the engine side cases, painting the wheels black and than work on the electronics box (battery) design more

anyways ill keep this thread updated!
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UPDATE:

So i started off by working on my wheels, i don't like the stock chrome walls so i decide to paint them all black, I give them a light sanding so the primer and paint would stick nicely, I think they came out nicely considering it was painted with spray cans.

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I didn't want to take the wheel off because i didn't have tire irons and also i didn't want to scratch them while reinstalling, so i covered the tires using painters tape and newspaper

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I used 2 layers of primer, 2-3 layers of paint, and 1-2 layers of clear coat. came out nicely

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I gave the wheels time to dry and once done, I decided it was time to start assembling some of the bike back together.

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I was pretty proud at this moment, it felt like my work was finally starting to show a little, this is how the bike is currently sitting. I just bought my battery online after a little research, I decided to go with Battery Tender Lithium LiFePO4.

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Now i know that it is a good idea to change the regulator / rectifier for a more current one, but i have a multimeter and i will do some testing to see if my current one is ok.

The next thing i am going to be working on is my Tank, I bought apple cider vinegar to clean the flash rust out and than i will use 2 stroke oil and gas to keep it from rusting again.

I original wanted to paint my bike With a white tank, but now i am having mixed feelings, kind of thinking about maybe just doing a blacked out look now. what you guys think? what you guys think white or black tank? (my seat is a dark brown color)
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UPDATE:

Started by painting the lower half of the engine Black

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Spent a bit of time sanding the HONDA letters to silver an than i did a clear coat

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Let it all dry for hours, and than proceeded to mount the engine. this is how the bike currently sits.

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Now i need to deal with this tank rust again.... I filled the tank up with apple cider vinegar and hopefully after a fer days it will be gone...

Soil Rust


I plan on working on the battery box and wire harness next.
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White, it's an unusual color for these. Here's the '82 CB450SC I sold
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yea i think your right, especially with everything else being blacked out. I think I'm going to go for Black tank , maybe add a little bit of silver decal.
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UPDATE:

Spend the day making a decent electronics box, my first one was a complete failure but my second attempt turned out really good.

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Just need a but more tweaking to get a perfect fit than ill paint it black. I also started putting my Wire harness back on. I ordered my headlight yesterday, But I'm still looking for a nice style of turn signals. Also trying to figure out a good way to mount the seat.
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Consider drilling drain holes at the lowest points in the event some water finds it's way in.
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UPDATE:

So i finished and painted the Electronics box, i think it came out good, i also started wiring stuff and get stuff fitted into the box.

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I also made a temporary mount for my Odometer, Yes it has 66000KM :lol:

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I got my front breaks on but they need to be bleed still.

Only have a few more things to do now, I have to paint the tank, and i'm waiting on the front/ rear headlight and turn signals to arrive.
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UPDATE:

Spend the day making a decent electronics box, my first one was a complete failure but my second attempt turned out really good.

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Just need a but more tweaking to get a perfect fit than ill paint it black. I also started putting my Wire harness back on. I ordered my headlight yesterday, But I'm still looking for a nice style of turn signals. Also trying to figure out a good way to mount the seat.
Where at did you get that seat? i rather like it...i just picked up a '82 CB450T last weekend
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