April 2010 18
Evan, what parts do I need in order to pull this off?
Well Wess, it depends what you’re trying to do. If you’re just changing the oil, adjusting the carbs, and adjusting the valves then you don’t need anything but an oil filter and some tools. What specifically are you trying to do?
I don’t think the bike has had an oil change in years! Definitely an oil change. I was thinking it might be beneficial to do a “general maintenance” tune up as I have done very little but replace the tires and fix a brake issue.
I don’t have much by way of tools…what would I need to adjust carbs and valves? The thought of doing those two things scares the crap out of me…NEVER done it, NEVER seen it done.
Hi Wess –
You really won’t need a whole lot of tools to work on the carbs and valves. A standard set of metric wrenches, 10mm, 12mm, 13mm, and 14mm, along with a few screw drivers should let you do most of it.
You’ll need some basic sockets to remove the valve cover, and you’ll need valve feelers to adjust the clearances properly.
If you buy a set of mechanics tools from Craftsman at Sears you’ll probably have everything you need (valve feeler gauges probably don’t come in the sets, but are sold separately).
Working on a bike is generally quite easy, even for a novice. Just follow the steps in your manual, read as much as you can online, and you’ll be fine. Take your time and have fun with it.
I picked up some oil and a new filter, along with the gaskets. When I unbolted the oil cover I barely had 1/2 quart of oil come out. Am I missing something? Is it possible that it only had that little bit of oil in it, or am I missing another oil compartment somehow? The honda dealer sent me home with 3 quarts of oil, saying that I should need around 2 1/2 quarts.
Could it really have been down nearly 2 quarts of oil? That is awful.
The CM450 (and all Honda CM’s) are wet sump motors. If I remember correctly the CM450 oil capacity is just a shade over the 2 quart mark.
You need to drain oil from the oil drain bolt on the bottom of the motor AND from the oil filter housing. Did you get both?
I did the filter housing first, then just unplugged the bolt and THERE IT WAS! Just finished cleaning up, thanks for your help with the oil change.
I do have another question. The previous owner of my bike decided it would be a good idea to put straight pipes on it. Despite it’s little 450cc’s, it is loud and slightly obnoxious. Do you have any idea how I could quiet the thing down without spending $200 (only spent $300 to buy it) to purchase a new exhaust system?
Are the pipes one solid straight pipe? Or are they the original headers with a straight pipe clamped on as an extension?
If they are a full solid pipe then really your only bet for a cheap exhaust is watching eBay and checking out your local scrap yard. If you have the headers then you could mount up some inexpensive new dunstall or similar style universal mufflers. You can usually get a set of those for around $100.
If you plan on keeping the bike a while then a new exhaust isn’t a ‘terrible’ investment. But that $300 sure can go a lone way when replacing brake pads, tires, cables, etc.
after all my searching I finally found the manuals for my 86 KTM 250!
Since you have a similar bike I thought I would post the link to the site where I found the manuals so you and everyone else can have access to them.
This is a link directly to the users profile who uploaded the manuals.He has many KTM manuals uploaded.
You can view the manuals on the site or sign up and download them.
Hope this helps you and anyone else looking for these rare manuals.
Awesome Fry. Thanks for the link. I appreciate you following up. Looks like he has TONS of owners manuals on there. Is he a KTMTalk member? I assume so.
took out the plugs of this bike and plug #2 came out real hard .got it out and the threads are stripped ,in the head . man really can use some help to fix this dying to ride this bike.
That’s a bummer! Fairly common problem on old bikes. Especially ones that have had the same plugs in the head for a couple dozen years. A little oxidation builds up then as you remove the plug, the threads tear themselves.
To fix it you’ll only need a couple things. You’ll need a metric tap that matches the thread pattern. Carefully run the tap through the hole to clean and recut the threads as best as you can. Use some grease to prevent metal shavings from falling into the cylinder (or remove the head). Then go down to NAPA or a similar shop and get a helicoil insert for the hole. Once installed you should be back in business and ready to ride.
If the hole is really massacred you may need a machine shop to repair it. But in most cases the above will work just fine.
hey evan your a great guy fast response to my question and thanks bro glad I found your site . always nice to have a site to go to where a bro cares enough to help a bro out thanks again bro PETE
No prob pete – happy to help.
Just take care to make sure the tap is going in nice and straight. Be gentle, take your time, and get your bike back on the road.
Is it possible to adjust the rear suspension on it? I just want to drop it a little.
The Honda Nighthawk 450 has slightly adjustable shocks, as do most dual shock bikes of the era. If you look at the bottom of the shock, below the spring, you seen an odd wave. As this wave is rotated around it can be set to put less or more tension on the spring. If you drop the spring slightly the bike will sit a touch lower – but not much. The load on the spring can only be adjusted with the correct tool – consult your service manual for tool information and the best procedure.
If you are looking to drop the rear end an inch or two your best option is to replace the shocks with something shorter. However, keep in mind that lowering the rear will affect the handling of the bike on the road. Before you do anything I would make sure you do truly need it lower for your security. If you are a new rider you’ll figure out pretty quickly that it isn’t too difficult to manhandle the Nighthawk, even if you are shorter.
To lower the bike. Pull off one of the shocks and measure it from eye to eye. Then start shopping around for replacements that are shorter. Mikesxs.com carries a variety of rear shocks in different lengths that can be adapted to the Nighthawk. Any of the large suppliers will have them as well, you can check my list of preferred shops on the homepage of cycles.evanfell.com
My Hondamatic project has taken a turn. I replaced the turn signal blinker switch but now when I activate them the brake light now flashes taking needed power from the signals. I don’t even know where to begin.
Hi Doug –
Just to clarify – did you replace the turn signal switch on the handlebar? Or turn signal relay down under the side cover.
I assume the tail light was working properly before you made the ‘repair’ yes? And all you did was swap out the 2 prong flasher relay?
Please let me know specifically what you changed, and why you changed it.
Is the tail light still working when you hit the brakes?
As a side note – a bike with a weak battery will often allow the headlight and tail light to flash – but they will flash alternate to the blinkers. So for example, when the right blinkers flash, the headlight and tail light dim, creating the illusion that they are flashing as well. This is because the battery is too weak to provide enough power to the headlight, the tail light, and the blinkers all at the same time. Is this what is happening?
Sorry I forgot the details… I replaced a faulty ignition switch and the winker relay under the seat (two Prong). I am using a 12V power supply for small electronics that plugs directly into the wall. As for the switch on the handle bars that works just fine, and the brake light was a simple replace matching the OEM wiring.
The brake works perfectly when the switch is activated, and the daytime running light is on also when the ignition is turned. My only thought is that there is a crossed wire in the ignition or inside the headlight bucket.
If your brake light is flashing in unison with your flashers then you have a crossed wire somewhere. Here is a wiring diagram for your bike:
You are going to have to do a little wiring tracing. I would start at the rear of the bike (unless you have already mucked around inside the headlight). I would look for a melted wire, or a sheath worn from rubbing. Follow the wires from the tail light up to the main harness and do the same with the rear blinkers. Look for anything unusual. Also verify all the wires are connected properly and the connections are clean.
Then I would go to the headlight bezel and trace the front headlight wires. Use the diagram above and check all the connections for continuity.
It seems VERY odd to me that when you turn on your flashers your brake light flashes, but when you activate your brake light your flashers do not activate. If electricity is getting in one way, it’s getting out the other.
Please let me know what you find.
I’m restoring a honda cb 125s. i cannot find anyone that has or knows the correct size spokes in stainless steel. can you please help i need the front and rear spokes for a 1976 cb 125s.
I can’t help you with the spoke measurements – but I do know that the CB125 wheels are the same as the CB175 wheels, as well as the CL175 and CL125.
I’ll agree, parts for the smaller bore bikes are often hard to source. They were sold in smaller numbers and not a whole lot escaped the scrap yard.
I checked a few parts houses for you and didn’t come up with any. However, there are sets of new spokes for you bike on ebay right now. I suggest heading over there.
Additional notes from a reader:
Check out Buckanan Wheels and spokes. I saw them in Classic Motorcycle magazine. Google them
I bought a 1978 Honda CX 500. The problem. The battery died on me when I rode the bike home. I put new spark plugs in the bike and a new battery. It started up and rode strong for 3 solid days of riding. However, when I went to Portland over the weekend I returned to the same problem. It won’t start. It sounds like it wants to, but it just won’t. So I have been told it is either the voltage regulator or the alternator. If it is the alternator, my manual says I have to take out the entire engine to replace it. Would it be incredibly costly to have this work done for me?
I’m a bit lost at the moment. If the voltage regulator doesn’t fix the problem.
Thanks a lot for your help.
Sounds like your alternator to me. The CX500’s and CX650’s are famous for their alternators going out. It is by far the biggest weakness of those bikes. Everyone who owns one will eventually have to replace the alternator.
The alternator is on the rear of the motor, and because of it’s location it tends to get very hot. Over time the excess heat will kill it.
Weak output is the biggest symptom, and it will get progressively worse. As you ride your battery is draining and not being recharged.
I would encourage you to tackle the project yourself. You’ll be paying big bucks for a shop to do it because of the age of the bike and the labor involved. You will have drop the motor from the frame – however, the CX500 motor is actually very simple to remove. Just undo a few bolts and it drops straight down.
Sorry for the bad luck. The CX500’s are great bikes and are worth repairing.
Alright man. Thanks for the advice. I’m gonna run with it. I’ll try to tackle this wild drunk donkey of a problem and ride the open road on that beautiful bike.
Thanks for the help.
I just cleaned my carbs and replaced a few jets. My motorcycle starts but after a min. or 2 it stalls. what can be the cause of this? Thanks for your time.
I forgot to add my bike is a honda 1984 Honda VT700.
This could be a few different things. I’ll start with the easier stuff first.
1.) Dirty fuel filter or petcock screen. If you have an inline fuel filter make sure it is clean and flowing properly. Disconnect the fuel line from the petcock and make sure fuel flows out of the petcock at a steady and full stream. Older tanks can accumulate debris and rust in the bottom of the tank which will clog up the petcock. You can remove the petcock to clean it a bit.
2.) Dirty float pin, sticky floats, or improper float height. When the bike is stalling after a couple minutes it is likely that the motor is drinking fuel from the bowls faster than they are being filled. If your float height is wrong, or the floats aren’t rotating well it could prevent fuel from flowing as needed. Your float needles could also be dirty or sticking to the seats. Inspect the whole float assembly for dirt.
3.) Clogged vacuum line. I believe the fuel flow is metered by vacuum on your bike. If the vacuum lines are cracked or otherwise faulty it could definitely limit fuel flow.
4.) Low compression. If you motor is high miles you could have low compression which will cause the bike to run poorly or stall once it’s warm. When the engine is cold the cylinder shrinks so the tolerance to the piston is tighter.
Those are the 4 ideas that come to mind. I’d give them a check starting with number 1.
I also happen to have a service manual for your bike in PDF format.
PDF – 1984 Honda VT700 Service Manual Warning: BIG file. 193mb.
Good luck. Let me know how it goes.
I own a 77 XT-500. It runs great, easy to start, but needs some TLC beyond my capabilities. How can I find a shop that caters to vintage dual-sports? (in the Las Vegas area)… Thanks
Finding shops who have any sort of knowledge of older bikes can be a challenge. I would of course encourage you to do the work yourself. Anyone with a shop manual, a few common tools, and a free afternoon can figure out how to repair most items on their motorcycle – especially a less complex bike like the Yamaha XT500 singles.
However, if you prefer not to turn a wrench, I hear Complete Cycle Repair in northern Las Vegas does very good work and the owner is a vintage bike guy!
First I want to say this is a great site and it gets me excited to learn more about my motorcycle and how it runs. Thanks a bunch, it has already been very informative.
I have a 1982 Honda Nighthawk and it has a hard time starting. I usually have to hook it up to a battery charger or the battery will die and when I do I still have to spray some carb cleaner or something like that into the air intake before it will start. Once I have gotten it to start it doesn’t run super well until it warms up. Once it is warm it runs pretty well although one of the carbs spits what I think is gas. I am not really sure what this means but it does it while I am riding as well as while it is just idling.
My friends helped me clean and sync my carbs last year and I was thinking about maybe cleaning them again after it sat all winter but I wanted to do some more research first.
I don’t ride it very frequently so I am trying to fix it up and then sell it. Any help or advice you could give me would be great. Thanks.
Sounds like a fuel issue to me. I’d recommend pulling your carbs and looking at them again. If you are dripping fuel then you have a dirty or stuck float/float-needle. Start there and move on to the other jets. When idling are both your exhaust headers hot? If not you might have a clogged pilot jet. Start with the carbs – even after one season of sitting they can certainly be gummed up again. When storing any carbed motorcycle for longer than a couple weeks it is a good idea to drain the fuel from the carbs so it doesn’t gum things up. At the very least dump some sta-bil into the tank and run it through a bit.
Make sure you air filter isn’t clogged.
Hard starting / poor running can also definitely be an air leak on the intake boots. If they are cracked they could be letting air sneak in which will make the bike run poorly and be very hard to start. Carbs are the obvious problem though.