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Discussion Starter · #1 · (Edited)
Hey guys! I'm happy to join this forum. Just picked up an '82 Nighthawk CB450SC with 19k miles on it, clean title, in decent running condition for $450!
The main issues that I could find were lack of upkeep on some items and a few body blemishes, mostly on the tank. As well as certain after-market parts. (More on that later.)
It appears that the chain has some rust and hasn't been properly adjusted in a long time, as it's very loose. The sprocket could use replacing as well. The oil looks good, plugs look fine and the tires are decent, so it wasn't totally neglected.

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I had an issue with it losing power almost immediately after I bought it. It was fine during the test ride, but on my first trip after buying, it kept losing power and dying.
I don't know what caused it but I'm suspicious of old fuel. It was low, but not empty when I got it. (When this was happening, it turned over just fine but wouldn't start! Maybe some clogged lines or something else? I'm baffled.)
It died 3 times before I could get it to a station. But once I let it sit for a bit and filled it up, I had no issues keeping it running.

Other than that, it seems pretty sound mechanically. (But I'm no mechanic and am used to only basic maintenance, so there could be something I'm missing. Hope not! But for $450, I'm not complaining too much.)

I've previously owned a 1983 Yamaha XS400 and a 2012 Honda CBR250R. I recently just sold the CBR (a week ago) because I've already got a car and I just bought a truck.
I definitely wasn't looking for another motorcycle so soon but I just couldn't stay away when this deal popped up!

There are a few things I want to change or investigate though. I've got a copy of the owner's manual, so I'll be scouring that, looking for ways to address the following:
(I've sorted them in what I believe to be most to least important.)

  • New chain and sprocket
    As previously mentioned, I believe a new chain is in order. The sprocket looks okay, but might as well just replace it too.
    I'll have to research to figure out what I need and how to change it.
  • The clutch friction point seems off
    I have to release it nearly all the way before it finally catches. Is this as simple as adjusting the free play in the clutch?
  • The exhaust "pops" or backfires when I downshift and engine brake
    Is this normal? I've read in some places that it means the bike is running too lean. Any truth to this?
  • Front brake squeaks when braking at slow speeds
    Not sure where to start on this. I'll be checking the manual for brake maintenance. Maybe time for new pads?
  • The handlebars are not stock
    I do not like the way they're raised and turned so far inwards. It's almost a bit uncomfortable. It makes it weird to use the mirrors as well.
    Is there a guide out there anywhere for replacing handlebars? I've searched with little-to-no success.
  • The exhaust pipes/mufflers are not stock
    No idea why they were changed out, but I'd like to return them to the original design. Or maybe get a whole new exhaust system.
  • The chrome has a few rust spots
    I've already found a dozen different ways to deal with this. I'll be testing out a few methods soon.
  • The tank has a ton of scuffs, scratches and a few (mostly small) dents
    I don't know how realistic it is to get a new tank, I'll be looking. But I want to figure out a way to at least touch up the blemishes.
  • The seat has a few tears
    Not a real issue, just putting it on my list of things to address.
  • No center stand
    They were standard on these guys right? I had one on my old Yamaha and I missed it when I got my CBR. Oh well.
If anyone has suggestions for any of the above, I'd be very grateful to hear them.
Otherwise, thanks for checking out my post!

Ryan
 

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Welcome aboard. Looks to be a pretty complete unit, great price for it.
Clutch adjustment should fix the engagement question.
With non-stock exhaust you will get more of the decel popping, the air cut valves in the carbs minimize that if they are good.
Probably time for new brake pads and I'd also change the rear shoes due to age, they will delaminate and cause wheel lockup.
Bars look like they're from the CM series and your description says the same, called "buckhorn" bars. Terrible design. Dan's suggestion is good.
You'll need to find a good power chamber from a 450, CM or CB. Looks like the PO kept the front pipes, hopefully didn't cut the down. Mufflers are whatever you would like them to be.
Finding a good CB450SC tank is tough. I would try to fix what you have. First thing is to get it to a radiator shop to be cleaned and pressure tested. These particular tanks are prone to rotting away at the lower rear corners where water collects.
Center stands were stock on these models. You do need the CB450SC stand because it's longer than the rest. There's a spring and C-bracket piece that are needed as well.
 

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Welcome. I have the same bike in the same colour. Got it with 6500 km and now at 29000 km. A few issues that have cropped up for me. It has always been cold blooded unless I use it every day. It also has a hesitation about 4000 rpm that I have never been able to cure. Being a standard you sit very upright and I find that trucks really move you with their wind blast. But for my purposes it is a great bike... reliable and easy to maintain.
 

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Discussion Starter · #5 · (Edited)
Welcome aboard. Looks to be a pretty complete unit, great price for it.
Clutch adjustment should fix the engagement question.
With non-stock exhaust you will get more of the decel popping, the air cut valves in the carbs minimize that if they are good.
Probably time for new brake pads and I'd also change the rear shoes due to age, they will delaminate and cause wheel lockup.
Bars look like they're from the CM series and your description says the same, called "buckhorn" bars. Terrible design. Dan's suggestion is good.
You'll need to find a good power chamber from a 450, CM or CB. Looks like the PO kept the front pipes, hopefully didn't cut the down. Mufflers are whatever you would like them to be.
Finding a good CB450SC tank is tough. I would try to fix what you have. First thing is to get it to a radiator shop to be cleaned and pressure tested. These particular tanks are prone to rotting away at the lower rear corners where water collects.
Center stands were stock on these models. You do need the CB450SC stand because it's longer than the rest. There's a spring and C-bracket piece that are needed as well.
Welcome. I have the same bike in the same colour. Got it with 6500 km and now at 29000 km. A few issues that have cropped up for me. It has always been cold blooded unless I use it every day. It also has a hesitation about 4000 rpm that I have never been able to cure. Being a standard you sit very upright and I find that trucks really move you with their wind blast. But for my purposes it is a great bike... reliable and easy to maintain.
Welcome to the group. Here's an old thread that might be useful.

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

You've already identified the brakes, you may want to check the date code on those tires. Even with little apparent wear age can cause deterioration.
Thanks for the replies and suggestions everyone!
I've ordered new handlebars, grips and mirrors. That's enough aesthetics for the time being. Next is the chain, sprocket(s) and brakes. Then I'll look into getting the tank checked out, as suggested.
It's been starting fine, but doesn't sound like it's running 100% on both cylinders. I'll go through that checklist and see what I can do.
 

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Discussion Starter · #6 · (Edited)
Here's an update.

Ordered an oil filter, brake pads and picked up some oil and brake fluid, and replaced the spark plugs. Bars, mirrors and grips came in. Working on installing them when I have the time. Going to do the oil this weekend, bleed the brakes and prepare to install the new pads. Then finally I'll see about a new chain.
Also been running some B12 Chemtool through the system. I know it sometimes has mixed reception (seems like more 'yeas' than 'nays'), but I think it's helped the bike run a little better already; helping to clean up the fuel delivery lines and such. I'm just adding it straight to the tank and letting idle. At some point I'll try the suggestion to let a concentrated amount into the carb bowls, or whatever the process is. But what I really need to do is clean/rebuild the carbs. I'm just fearful that's a bit beyond my mechanical ability, resources, space, etc. for the moment. (I'm inexperienced, don't have many tools and live in an apartment complex with restricted space.) The left side is puttering out of sync with the right at idle. Gotta do the compression and sync test too.

Anyways, I'm also having trouble with the handlebar replacement. I've got some really stubborn screws on the clutch housing (not sure what it's called) to get it off the old bar. They are just a little stripped but I'm afraid of making them worse. I'll try the rubber band method when I get home today.

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Lastly, I want to know if anyone has a suggestion for removing the warning sticker on the tank without damaging the paint. Thoughts?
Thanks.
 

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Just follow the instructions on the can of B12 adding it to the fuel. No need to try and fill the float bowls with it. I'd run thru the ignition diagnosis sticky you'll find in the SOHC Electrical section as well as run a compression test. The carbs may just need to be sync'd and mixtures set instead of rebuilding/cleaning them. The more you can ride it to run the B12 thru the carbs the better.
Removing the tank sticker really isn't possible w/o damage since it was applied and then clear coated. Even when it gets sanded completely off to bare metal there seems to be an etching where it was.
I've ended up using an impact driver on the switch pod screws more often than not when they haven't been removed previously. You can try tightening them first before removing, that helps sometimes.
Tools needed are pretty minimal, experience you will gain and we'll help you. Space? can't do anything about that
 

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Discussion Starter · #9 ·
Just follow the instructions on the can of B12 adding it to the fuel. No need to try and fill the float bowls with it. I'd run thru the ignition diagnosis sticky you'll find in the SOHC Electrical section as well as run a compression test. The carbs may just need to be sync'd and mixtures set instead of rebuilding/cleaning them. The more you can ride it to run the B12 thru the carbs the better.
Removing the tank sticker really isn't possible w/o damage since it was applied and then clear coated. Even when it gets sanded completely off to bare metal there seems to be an etching where it was.
I've ended up using an impact driver on the switch pod screws more often than not when they haven't been removed previously. You can try tightening them first before removing, that helps sometimes.
Tools needed are pretty minimal, experience you will gain and we'll help you. Space? can't do anything about that
Thanks for taking the time to reply. I'll keep running the B12 through the system and find a way to complete your other suggestions.
The oil filter came in today. Changing that and the oil and working on the brakes will be my Friday night project.

I was also finally able to get the bars swapped out. The throttle tube extends a bit beyond the grip I bought, so I might just cut off a little bit of it.
Any suggestions for helping the throttle rotate better over the new bar without sticking? I can turn it but it doesn't snap back like I'm used to. Do I need to lube it a little somehow?



I'll stick the right side mirror on once I get the throttle movement smoothed out. :)
 

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Discussion Starter · #10 ·
Another question... (Very likely a dumb one.)
I adjusted the free play in the clutch and it seems a little better. But it's really stiff and requires a lot of grip strength to engage. My hand gets tired. Is this adjustable?
 

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For the clutch cable, you will need to re route it to get smoother turns. Feed it over to the other side under the gauges to get a longer curve. Any sharp curves tend to make the cable bind inside and feel stiff. For the throttle, since the bars are a little shorter, you will have to move the right switch pod/throttle out. The grip is likely fouling on the end of the bar at the end.
 
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