Newbie about to start my first build - '82 Honda CB450 Nighthawk

even if there isn't a factory method described,if the motor will run with cover off then timing advance can be observed
 
Ok, I printed out the shop manual and I plan to pick up a timing light on the way home. Goals for the long weekend: check the timing and the CDI/ignition coil, check and adjust the valves with another compression test after that, and check the air filter.
 
go thru the electrical connectors check for loose ones and corroded ones and address that as it goes
it is tedious work but doing it now is wise in my hoe
 
You're right XB, better to do it now and know they are all good. I'll add that to the list.

Does anyone have a opinion about working with the bike on one of those small lifts? Not the platform ones that you see at shops but the small ones. I trying to decide if its better to use one of those (not sure about stability once the bike is one it) or to just build a raised platform like I have seen several people do on here. I assume there is a reason, such as better stability and not just a desire to sharpen up carpentry skills, that a lot of people opt for the platform.
 
a platform is much better in my hoe and nothing wrong with a stationary one just dont go to high
15-18'' is about right unless yer tall
 
Thanks XB. I'm only 5'8" so I was already thinking 18" max. I need to build a few shelves in my garage anyway so I'm thinking that while I'm at it I might as well go ahead and build a platform.
 
I haven't gotten my hands on a timing light yet, but I did pull the ignition coil and do a resistance test on it. The numbers are not what the manual is saying they should be so I'm going to go ahead and replace the coils. The spark plug wires appear to be in good shape but I think I will go ahead and replace the those as well since I have no idea how old they are. Once I have new coils, plug wires and caps those will no longer be an unknown. Next up is to go ahead and check the valves.
 
if the coils were bad i dont think it would run at all, i feel you should get known good adjusted float level ,cleaned non leaking carbs on it before throwing money at ignition coils, new plug caps and new sparkplugs only for now is the way i wood doit
.....motorcycle plug wires are not like on a car they dont go bad the outer casing can crack and cause a short or leeking spark but that is all they have a solid wire core not carbon
 
I was just flipping through the manual I have and I happened to stop on the page that explains how to pull the tank. It mentions disconnecting the fuel line and a vacuum line that runs from the fuel cut off to the carbs. When I pulled mine the only thing I had to disconnect was the fuel line, there was no vacuum line. I double checked it and I can see where the vacumm line would attach on the carbs but I don't see anyplace for it to attach on the fuel cut off. Could that missing vacuum line with the reason it's dying at about 3500 rpm?
 
having the vad line open would cause an air leak situation much more likely to only effect running at lower revs
so the petcock has no provision for a vac line? if so then just cap off the open vac port at carbs,go ahead and test fire the bike as well after eaach change/fix
make sure the gas tank will freely flow gas for a long time (put longer gas line in a jug ,let'r rip)just to make sure gas cap vent is clear not clogged
 
Yeah, the vacuum port on the carbs had already been capped so I figured it wasn't an issue but thought I better ask. And thanks for the tip on the gas tank and vent cap.
 
What numbers did you get for the coils and were they completely disconnected or still connected to the CDI box? IIRC there are two CDI systems at least and two very different specifications.
 
The first time I took readings on them they were on the bike. According to the manual I should have gotten .55 to .65 ohms when checking resistance between the two primary terminals and a reading of 7200 to 8500 ohms when checking by inserting the leads for the multimeter into the spark plug caps and measuring between the spark plug leads. I got a reading of .2 between the primary terminals of the coil and a reading of 17,300 ohms between the spark plug leads. After I removed the coils from the bike I took the readings again and got no reading between the primary terminals and got the same 17,300 ohms between the spark plug leads.

Maybe I'm confused but the manual makes it sound like the Rebel 450 uses a CDI but that the Nighthawk 450 uses the ignition coil without the CDI box. Is that correct?
 
IMO, you're problem sounds carb related. Main jets are prolly clogged. And if done correctly these lil motors can make a nice amount of power.
 
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