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Refurbishment on a 1984 CB450SC

Flyin900

Flyin900

Veteran Member
Joined
Nov 28, 2020
Total Posts
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Location
Canada
I am still scanning our local Kijiji forum for Honda bikes and parts, as I am curious what is for sale, plus some of the interesting (being kind) bike projects that pop up on there from time to time.
So a 1984 CB450 Nighthawk was offered up about two weeks ago with only a partial picture showing for the ad with a price of $1000. I didn't bother opening the ad, as I have stopped restoring bikes. :ROFLMAO::unsure:
So yesterday the same ad was showing a price drop to $500. which peaked my interest. I contacted the seller and I am headed over there tomorrow to possibly purchase the bike. It has sat for 20 years and it looks fairly decent. Picture lie though, so I spoke with the seller and it sounds promising including a title and a key for the ignition.

If I do purchase it I will do a follow up post and likely a build post next year, when I am ready to spend some time with it.

I was able to convert these files from the Kijiji ad to JPEG and that's a miracle that I figured that out. (y)

So here's the potential new purchase as originally advertised.


CB450 1.jpgCB450 2.jpgCB450 3.jpg
 
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Looks like a very nice start of a project. I look thru the upcoming auction listings fairly regularly. I usually am not interested till they only bring $500 or less. Then I’m interested. lol. I’ve been buying vintage cast iron skillets and restoring them before selling to make my “bike” money. 😁
 
2wheel said:
Looks like a very nice start of a project. I look thru the upcoming auction listings fairly regularly. I usually am not interested till they only bring $500 or less. Then I’m interested. lol. I’ve been buying vintage cast iron skillets and restoring them before selling to make my “bike” money. 😁
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Rarely is there anything $500 bike wise on Kijiji around here anymore, even $1000 is a rare sighting on there these days. Some of the scary $5000 projects are pretty hilarious, when you see the amateur work that was done.
 
Flyin900 said:
Rarely is there anything $500 bike wise on Kijiji around here anymore, even $1000 is a rare sighting on there these days. Some of the scary $5000 projects are pretty hilarious, when you see the amateur work that was done.
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I’m not trying to enable you or anything but I use auctionzip to peruse local public auctions and find quite a few vintage bikes. Edit. I just noticed your in Canada. Might not be an option.
 
It can become a very legitimate passion problem. I find myself skimming through Marketplace all the time and I’m positively out of space unless I start stacking bikes or moving them inside the house.

N+1 formula
 
Nice looking CB450SC Flyin900 and I Love those stripes on that model/year.
Some 450SC's have weathered a bit with those stripes and they have a shine like complete shiny silver,all the way across.
 
zhuffy said:
Also I just realized that your Canadian gauges aren't limited to 85mph, lucky!

View attachment 37945
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Honda reverted to those 80 mph gauges in the US for a time I believe. We have been on the metric system since around 1978, so it never came to Canada with the reduction on our gauges.
 
bilbikek411 said:
Nice looking CB450SC Flyin900 and I Love those stripes on that model/year.
Some 450SC's have weathered a bit with those stripes and they have a shine like complete shiny silver,all the way across.
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Thanks Bill seeing will be believing as the bike looks decent in the pictures. If I buy it I will likely fix it and sell it next season along with my CB550K and possibly the CX650E
 
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So I bought the bike as it was in unmolested condition complete with 90’s date coded Bridgestones on it. It will need a good clean up and the usual reconditioning of common wear parts replaced.
I thought it was black in colour, yet it is a dark blue metal flake factory finish. The 20 year old gas was really stinky, so that has been removed and the tank is quite clean metal.

New pictures to come once I clean it up from 20 years of sitting in a shed, yet it was covered in there which seems to have kept the rust gremlins at bay.
 
Thanks Jim I will check for that as I just got the bike home later today and did look it over quickly. Hopefully there isn’t that issue, but you never know.
 
LOL
EzPete said:
Nice! Looking forward to that restore thread. Or are you going wild with a chopper mod?
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I am going to put it back to original condition, since that is what I do. I enjoy seeing some bikes modified when appropriate and in poor original condition.
This one is very original bIke based on my first overall assessment with all the original parts intact. It looks like it was a two owner bike from new confirmed by the paperwork that I received. The odo reads 8600 kilometres, so about 5K miles and it shows in the original condition as it currently presents.
 
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boddy said:
Looking forward to your build, glad you did not hang up your tools just yet.
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Well I will always have tools it seems and I am willing to help fellow riders and CVMG and VHT members with their projects. This one just looked too good to say no and the price was right, so far it hasn't disappointed.

I sprayed it with a degreaser and then brushed and wiped off most of the 20 years of crud, yet it was kept in a shed under a cover. It shows that the past owner and the original owner must have kept it from the elements. It cleaned up really well without doing any serious detailing to get it to shine.

My plan is to not do too much other than the mechanical stuff that it will need and some light touch ups. It is rust free mostly, so the carbs will be the first stop since the gas was pretty stale in the tank. Once I have the carbs done I will attempt to get it running and then do the mechanical checks on the valves and cam chain etc. I have the cylinders soaking in Deep Creep and will roll the motor over by hand to verfiy it is free. The gas tank is very clean and no evidence of any rust out where LD indicated these are prone to rust.

I will check the cylinders and rear of the gas tank interior with my borescope later, as I move a little further along in the process.

So here it is after a bath. (y)

P1100028.JPGP1100030.JPGP1100032.JPGP1100033.JPG
 
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Well I got lucky with this one and the 1978 CB550K with both bikes in amazing shape and low cost projects. The backstory on this one is the gentleman who owned it passed away and his son was here from Australia where he lives now to do the estate clean up. So he was on a time constraint, as he was going back to OZ this weekend and needed this and some other items gone now.

I think the $1000.00 price was reasonable initially. I didn't look at the ad when first posted at that price as I previously noted. I think his description in the ad possibly turned some potential buyers away. He included it hadn't run in 20+ years and clearly it needs tires and the front caliper was seized and not able to move the bike from the shed. I assume he had a few calls but no one stepped up.

So when I saw the ad again recently he had reduced it to $500.00 and I looked at the ad for the first time. It looked decent and it was relatively close within 1 hr to me. He didn't say he had the title or a key in the ad, so I sent a few questions and a request for a contact number. After talking to him I was pretty sold that it was a contender, yet I have bought lots of bikes over the years and they never look as good as the pictures show!

He had the paperwork from when his dad bought it used in 1994 for $1200.00. That is sometimes the reference point for sellers, or in this case it needed to be sold right now!
Once I got there and looked it over the sale was a done deal, so I removed the brake caliper to get it to roll and off we went back home.
 
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LongDistanceRider said:
It's so nice to see a complete unmolested clean CB450SC (y)
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Thank's Jim it is really in good shape with no signs of rot in the gas tank area you referenced and the crossover muffler chamber looks really solid as do both mufflers. The proof will be if it starts and runs well once I get to that point. I am optimistic since it is a low kilometer bike and hopefully with some new tires and a chain and fork seals and battery it will be close to road worthy.
 
Flyin900 said:
So here it is after a bath. (y)

View attachment 37999View attachment 38001
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WOW.
Just... WOW. What a perfect bike, even has the reflectors untouched (nicknamed cat eyes around here)...

I've never been a fan of custom bikes, be it japanese or smaller ones, just didn't resonate with me, I even looked at the CB450SC online when I bought my DX and didn't feel anything about it, but this... This is 10 out of 10, amazingly beautiful bike. I think I'm changing my opinions about the Nighthawk 450...

The one, single thing that I don't find so amazingly beautiful about the bike is the engine's head cap. I think the CB450DX head cap fits much better with this engine (where I live, the 450SC cap was only used in the 400's) - I'll post a pic below.
But the rest? Damn... I might also just go looking for a chrome chain guard that I can modify to put into my 450DX... The shorter muffler (compared to the 450DX at least) also looks very nice. Also, that engine paint looks so freaking new it makes me want to spend money I don't have to get mine painted, congrats on the new bike/project, may it treat you well.

450DX head cap:
1728522321517.png
 
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I worked on the bike today and discovered a number of frayed wires in the taillight area that are wired to the rear brake light and the running light in the rear fender nacel. There was a bunch of leaf and pine needle debris, so I suspect mice or a chipmunk nested there and chewed on the wiring. The brown wire was severed close to the taillight and the green and yellow stripe wire and the grounds in the main harness were chewed around the insulation. Soldered the repairs and heat shrink and it looks good again.

The front caliper was quite seized and the two pistons needed heat and some chemicals to get them to remove with compressed air. (USE CAUTION WITH COMPRESSED AIR WHEN REMOVING THE PISTONS). One piston is pitted so I think I have a used one in stock in better shape. I have the carbs off and they were not too bad inside with still fluid stale gas and not too much varnish in the bowl area. I have them in the ultrasonic presently and I don't need to break them down completely. The air cut valves are accessible on both carbs, so I could remove all the rubber internals other than the fuel rail O rings. I will roll the dice there, as they are low mileage and the rubber bits still look decent that I removed from the fuel screw O rings to the air cut diaphragms.

Before pic after removing the pistons and old seals. Pretty crusty with old brake fluid and white crystalized baked on crud inside the seal areas. These need to be pristine clean in those grooves. Even a small amount of leftover crud in there will stop the new seal from seating properly and bind up the piston when reassembled.

P1100049.JPG



After with the seal slots cleaned and ready for some bead blasting then paint and new seals.


P1100055.JPG


Here's the bike with the rear bodywork removed which made getting the carbs off easy.


P1100053.JPG



Chewed taillight brown wire before the repair



Taillight damage.JPG
 
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Here are the carb bodies just out of the ultrasonic and rinsed and I tested the accelerator pump nozzles for proper flow which they passed. I will use my steam cleaner to shoot steam through the small internal passages as a final check. These CV style carbs have some pretty small passages related to the pilot and air cut circuit. These are a little less complicated than the 4 cylinder versions that have a mid range jet circuit too.
The steam machine is a great little helper if you do a number of carbs in a restoration and it's not too expensive. I think I paid around $50.00 off Amazon a number of years ago. It can be used to clean areas on the motor around the fins and crevices, plus some household chores too. :ROFLMAO:

P1100058.JPG
 
I keep waiting for some PO madness to come out of this thing, but it looks more and more like a bike that was legitimately not ridden that much, somewhat properly stored and just left there.

Where’s all the corroded bolts and screws and mismatching hardware? Spliced electrical with red wires for grounds and plastic connectors?
 
EzPete said:
I keep waiting for some PO madness to come out of this thing, but it looks more and more like a bike that was legitimately not ridden that much, somewhat properly stored and just left there.

Where’s all the corroded bolts and screws and mismatching hardware? Spliced electrical with red wires for grounds and plastic connectors?
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Well so far it meets that “ cream puff” moniker from the old days. It was not molested that I can see at least on the frame area. I haven’t been into the headlight bucket yet.
I didn’t think there was a tool kit present, yet when I removed the rear plastic door into the tail section compartment there it was and the tools are brand new looking in the blue pouch.

Getting it running will be the ultimate test of its fitness. I don’t want to get into any motor work, beyond setting the valves and timing chain and the balancer chain set up. All the other mechanical/carb/tire stuff is mandatory when a bike has sat for 20 years.

I fortunately have many of the parts and seals in stock, so hopefully a new battery and tires will be the other financial costs.
 
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I fiddled around more today and cut the old chain off the sprockets as it was a peened master link and was in sad shape from sitting and likely zero maintenance over the years it was used. I pulled the rear wheel and had to get the big hammer to drive out the axle shaft. It was semi seized I think from petrified grease and it took some work in spinning the axle with an air tool to help break it free.
I will check all wheel bearings and may need to replace those in the rear wheel if they are gummed up too.

I am cleanings the carb jets tonight after soaking them in lacquer solvent for about 6 hrs which is my usual method these days. I am now boiling them in a 50/50 mix of distilled water and 5% white vinegar for about 30 minutes. This will help remove any remaining softened stubborn gas varnish and as a bonus the vinegar cleans the brass back to a nice shiny surface.

I also have the front brake caliper finished and painted today. Then onto the master cylinder and getting it apart gave me some grief. The small spooge hole for the pressure return was plugged solid and not accessible without removing the top plastic fluid reservoir. In trying to clear it with brake clean it has damaged the factory finish, so I stripped it and its ready for primer and paint again. That C clip is a challenge to gain access to the plunger valve especially when rusted into the housing, so that took some work to come away with a win.

The parts could possibly be reused from the master cylinder, yet I am going to replace the plunger kit and the O ring seal for the plastic fluid reservoir. Nothing like using old parts on repainted pieces and the brake fluid leaks and ruins them again. That said I have converted some of my other master cylinders to DOT 5 synthetic which doesn't attract moisture I believe and won't damage the finish.

Carb jets ready for a lacquer solvent bath.

P1100059.JPG

After a solvent soak and ready for a further clean with distilled water and white vinegar boil.


P1100065.JPG


Now boiling for 30 minutes in a small pot on the stove. No muss and no fuss it is pretty straight forward.


P1100068.JPG


Front Master cylinder now ready for some primer and the VHT semi gloss caliper paint. I bought some body shop supply Aircraft paint stripper and it works way better than the Home Depot stuff, although it is twice as expensive too.


P1100064.JPG
 
I just pulled the carb brass out of the water and vinegar boil and they cleaned up well. I will run the small jet cleaning wires through all the jets and emulsion tube holes as a final check. Especially the slow jet which has a very tiny hole and prone to not always being fully cleaned if your not familiar with the tiny passages both in this jet and the circuit within the carburetors.

This is a cross section of a slow jet cutaway as an example of how small that passage is in the bottom of that jet.

Slow jet.jpg


Here are cleaned the brass pieces ready for a final check over before reinstallation into the carb bodies.



P1100070.JPG
 
Thanks for sharing your tricks with carb cleaning, I like the little steam cleaner. We need all the help and tricks we can on these carbs, I don't think the ultrasonic cleaner is a magic bullet, I'm sure they are great, but nice to have a number of methods to use. That is a nice looking bike for such a great price, and I do like the 450's with the extra 50cc over CM400 and I assume it has the 6th gear which I am also keen on. Great find!
 
kbongos said:
Thanks for sharing your tricks with carb cleaning, I like the little steam cleaner. We need all the help and tricks we can on these carbs, I don't think the ultrasonic cleaner is a magic bullet, I'm sure they are great, but nice to have a number of methods to use. That is a nice looking bike for such a great price, and I do like the 450's with the extra 50cc over CM400 and I assume it has the 6th gear which I am also keen on. Great find!
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An ultrasonic unit just makes it easier and faster. It still takes time and patience to get them right the first time.
The 6th gear is nice but it's a cruise only gear used above 50-55 mph. Used at lower speeds puts the engine below the power band and will strain the gear until it breaks. Honda had an issue with 6th gear breakage which resulted in the warn light being added.
 
Flyin900 said:
Well I will always have tools it seems and I am willing to help fellow riders and CVMG and VHT members with their projects. This one just looked too good to say no and the price was right, so far it hasn't disappointed.

I sprayed it with a degreaser and then brushed and wiped off most of the 20 years of crud, yet it was kept in a shed under a cover. It shows that the past owner and the original owner must have kept it from the elements. It cleaned up really well without doing any serious detailing to get it to shine.

My plan is to not do too much other than the mechanical stuff that it will need and some light touch ups. It is rust free mostly, so the carbs will be the first stop since the gas was pretty stale in the tank. Once I have the carbs done I will attempt to get it running and then do the mechanical checks on the valves and cam chain etc. I have the cylinders soaking in Deep Creep and will roll the motor over by hand to verfiy it is free. The gas tank is very clean and no evidence of any rust out where LD indicated these are prone to rust.

I will check the cylinders and rear of the gas tank interior with my borescope later, as I move a little further along in the process.

So here it is after a bath. (y)

View attachment 37999View attachment 38000View attachment 38001View attachment 38002
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WoW !! that's a very nice gem. :cool:
 
So I cleaned the caliper up and the master cylinder as noted previously and repainted them with the VHT semi gloss caliper paint. It closely resembles the original Honda paint colour. I will give it a day to cure further then follow the instructions of heating to 200F for 1 hr to assist the paint in chemical resistance. I use my BBQ for that procedure to keep the smell down and it has worked well in the past. This paint won't withstand any conventional brake fluid though even after the heat treatment.

One of the caliper pistons is pitted around the area where the outer dust seal sits and it may be an issue with crud getting past there to the fluid seal. I thought that all these twin pot calipers were the same... not so on these twins vs the inline fours or Goldwings from that era. The more common set of calipers takes a 30mmX35mm piston, where these take a 30X31mm piston, so a little shorter. The brake pads are different in alignment too vs the more common pads I have in stock.

The shorter ones are NLA from the usual sources. I found BrakeCrafters has a correct manufactured aftermarket SS piston for around $75.00 shipped with taxes from the US on EBay. Plan B is to ask my friend Paul first who has a lathe to see if the 35mm ones can be cut down to 31mm which would be a much cheaper option.

P1100072.JPG
 
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I have the carbs cleaned and ready to go when the time comes. I was able to do all the procedures I have outlined and the last test is the fluid leak test with 70% isopropyl alcohol (cheaper) which I find to be a nicer fluid to work with off the bike.

So here is the progress in the reassembly. I took lots of pictures yet I will post the key ones and the float level gauge ones were a blur with not enough hands. ;)

Installing the interior air cut diaphragm with a small ratchet driver to do the final tightening. It is a difficult spot in there, yet way more room than a bank of four carbs.

P1100075.JPG

Bottom all buttoned up and the accelerator pump circuit tested in the float bowl before installation with some alcohol in the bowl.


P1100086.JPG

Black kidney shaped seals installed over the air cut valve upper inlets and the white slide cushions installed with the lip side facing up.


P1100084.JPG

Slides and springs installed and ready for the cap covers.

P1100087.JPG

I installed the caps and discovered that the slides were binding slightly in the cap and inner slide tube assembly.


P1100095.JPG

So I removed them and with 2000 grit sandpaper I carefully sanded both the inner cap brass tube and the male slide tower to dress them up. Likely some remaining cleaner from the ultrasonic or other material. I used the body of a sharpie pen with the 2000 grit and a popsicle stick for the interior of the slide with the same sandpaper.


P1100088.JPG
P1100089.JPG

The last job was to install the fuel screws in the correct order of the spring/flat washer and O ring with a little WD 40 to assist the ingress into the body. These are a tight fit as the spring will bind sometimes with the fine thread inside the tower, so WD40 helps the installation.

P1100092.JPG

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Resting along with the other parts that have been refinished.

P1100096.JPG
 
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Carbs look cleaned up nice. I like the idea of testing with isopropyl alcohol. Some of my ratty carbs I'm working on came with the cylinders stuck hard and required some persuasion to release. They had some oxidation on the surfaces. I used a fine steel wool, that seemed to work to clean them up. Note the black kidney shaped piece is over the primary and secondary air passages, not on the air-cutoff side with it's two air passages.
 
kbongos said:
Note the black kidney shaped piece is over the primary and secondary air passages, not on the air-cutoff side with it's two air passages.
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Absolutely correct. It’s been a long day:) The steel wool is a great choice too. I hand cleaned the slides and caps now that I think about it, not the ultrasonic cleaner, so it was likely gas varnish on those slide parts.
 
Windmill John said:
You lucky bugger… great thread, great looking bike and well done.
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Thank you. It has great bones as the saying goes :) Kind of the polar opposite of the one your currently working on, yet I admire your determination and you got it running recently I believe.
 
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I pulled the rear wheel a few days ago and the axle was hard to remove, so I checked other areas such as the swing arm and while it moved up and down it was not as smooth as it should be and was binding in some areas. So off it came and I cleaned the slung chain grease/dirt mix off it and then I have done a more detailed clean up of the rear engine output shaft area. This was was also caked with petrified dirt and old chain oil. Give me a shaft drive rear end anytime over a chain, since they are much dirtier and require lots of regular maintenance.
It now is decent enough and I won't do any further work or paint as it is good enough. I do want to drop the exhaust system down slightly without removing it from the head, or breaking it apart at the connection points. The exhaust chamber has some surface rust yet appears to be very solid. I can spray some VHT exhaust header paint onto the top and bottom to refresh it and clear up the surface rust. A job for another day.

Cleaned rear section less the main stand area, as I had plastic tubs there to catch the varsol and engine degreaser as much as possible. A clean up job for later, as I will support the engine area and retract the main stand to the point where I can remove it and the spring easily with the swing arm out of the way. :unsure:

P1100097.JPG

Output shaft area less all the gunk. ;)

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P1100099.JPGP1100100.JPG

Top of frame now cleaned and ready for the installation of the tail section again. There is even the sticker on the cross bar piece with the bodywork paint code. There are still the witness marks in yellow on some of the key bolts from the factory, so further support as a clean original bike.
 
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