Topic: 650 Nighthawk SOHC, I seem to have lost my paddle in this creek....

[coffee_brake]

I'm trying to search the forum to find out how to check out everything before I put fuel to this bike. I've never worked on a SOHC before.
I'm having trouble figuring out what the terminology of this bike is. Are all the SOHC 650s the same?

I'm lost even trying to check the valve clearance, it's kind of funny, I always turn the motor until each of the two cam lobes are opposite each other to find TDC of the cylinder in question, but that's not going to work here!

The bike is very original, I even have the clearance specs plate still riveted on the frame. But I'm not sure what resources I'm looking for that apply to this one-year model.

Also...one of the synch ports on only one carb is missing. Is it supposed to have an aluminum plug just like the other three?

[Powderman]

You want TDC on the compression stroke so both valves are closed.

[coffee_brake]

Um...where is it recommended that I turn the motor?

I also need the instructions to adjust the cam chain tensioner and ignition components.

Looks like the Clymer for the 79-82 CB650 is the best bet? I can't seem to find one available to download...

[coffee_brake]

I found the Honda manual here (many, MANY thanks!) but I'm a Clymer sort of gal myself. Any chance one of those is running around? Also, by reading the 650 manual, I can tell that the air cleaner is different and the carbs are VERY different from the Nightahwk's.
In the meantime, I can get the info I need for the most basic stuff from what's available here. Much appreciated!

[cb650]

Someone on the 650 site has a link to a online manual.  The clymer is best for me as that is what I always had.  Haynes is good to but most work is on the Z models so looks a little diff.  All the 650 engines are mostly the same.  The carb/head changed in 81 and a couple other little things but all tuning is the same.  Post some pics.  I have a nitehawk also.  Love to see a nos one.  Where u at?

[coffee_brake]

Someone on the 650 site has a link to a online manual.  The clymer is best for me as that is what I always had.  Haynes is good to but most work is on the Z models so looks a little diff.  All the 650 engines are mostly the same.  The carb/head changed in 81 and a couple other little things but all tuning is the same.  Post some pics.  I have a nitehawk also.  Love to see a nos one.  Where u at?

Which are the Z models?

I'm in GA, I really like Nighthawks. I have this 650, and a 700S, and a 750 (92). This 650 is in the best original condition. I'm actively looking for a 450 Nighthawk, just love the styling on those with the light weight. And I'm a sucker for a CX500 too. Also a '86 VFR750. Vintage Hondas are so much fun and I'm learning a lot with this one!

[Powderman]

Not familiar on the 650 where to turn the motor. One method would be to pull the plugs, put it in gear and turn the wheel in a high gear.

[coffee_brake]

OK thanks, I also see in the Honda manual where I should turn the motor. I'm going to need to be able to see the timing marks. On other bikes with two cams, I just bump the starter till the lobes are opposite each other.

does the 82 650 Nighthawk share front end components with the other SOHC 650s? Is the front end geometry the same? Other than the plastics, what else is different?

[cb650]

The US 79 Was a Z.  The rest of the world got the Z till 84 but it was a little diff than the us Z.   Take off the right crank cover and use a socket on that 15/16 nut.  Dont go backwards to much and dont force it.  It actually goes into a very small shaft under the advance unit.  Be sure not to move the pickups.  I have a 84 dual cam I'm parting out if anything will fit the 700.  Did you join the nitehawk site.  I did but gave up.  The other 4 I'm a member on is enough.  Spend way to bunch time at the pc anyway.


Fronts are all diff then the other 650's

[coffee_brake]

The US 79 Was a Z.  The rest of the world got the Z till 84 but it was a little diff than the us Z.   Take off the right crank cover and use a socket on that 15/16 nut.  Dont go backwards to much and dont force it.  It actually goes into a very small shaft under the advance unit.  Be sure not to move the pickups.  I have a 84 dual cam I'm parting out if anything will fit the 700.  Did you join the nitehawk site.  I did but gave up.  The other 4 I'm a member on is enough.  Spend way to bunch time at the pc anyway.


Fronts are all diff then the other 650's

I was extremely active on the Nighthawk site till they got their heads up their butts the past year. I don't like to go there anymore, the head honcho there is a real pig.
My 700s is covered up till the 650 is ready to ride, I only have room to work on one bike at a time. I'm hoping I won't need much but the charging system is suspect already.
So this is a 650Z...I think?

[cb650]

no not if its a nitehawk.

[MiGhost]

You will find that the 82 650SC Nitehawk is very similar mechanically to the 81 650C Custom. The major differences being mostly cosmetics.

The front end is a different story completely. The forks are a larger diameter, and the triple tree is completely different on the nitehawk.

When you get to the front brake system. Look at the 82 CB750SC for the obsolete pieces to rebuild the calipers. I have a write up on the 650 site with all the interchange info on the front brakes.

[cb650]

http://www.hondacb650.com/index.php
More 650 specific info.  Lots of members from overseas with the Z models.  Check out the show it off section.

[trueblue]

This is an Aussie model CB650Z (with a funny seat). 

[cb650]

Very nice bike.   Mostly like the us Z (79) except the wheels dual disks and the tail light.   Always liked the taillite on your Z's

[fmctm1sw]

I'm lost even trying to check the valve clearance, it's kind of funny, I always turn the motor until each of the two cam lobes are opposite each other to find TDC of the cylinder in question, but that's not going to work here!

I always just look at the intake valve.  Once it gets on it's way back up I look at the points plate for the F/T marks.

Also...one of the synch ports on only one carb is missing. Is it supposed to have an aluminum plug just like the other three?

That may be for the dreaded vacuum petcock thing.  I think it's the #2 carb.  I've always just ran a line straight from the tank to the carbs and used another sync screw in that like the other ones.

[coffee_brake]

Thank you, thank you. VERY good and much needed information!

I was beginning to wonder about the calipers, they are certainly going to need a rebuild.

The front master is a complete loss, I'll have to run one of the new aftermarket units. I've had good results with them before.

First things first though, and that's valves and cam chain, then try putting fuel to it.

That Z is a handsome machine all right. These 82 plastics are a one-year only thing, if the bike hadn't come with the side covers I wouldn't have jumped on the deal. Less than 8k on the clock, which can be a good thing or a very bad thing. We'll soon find out.

[trueblue]

Thanks, I bought it as a wreck and put way too much money into it, but everytime I ride it I'm glad I did .  I have an '82 SC in the shed it came without the tank and sidecovers, took me over a year to find them and when I did I had to pay through the nose to get them.  Now I'm just waiting for some more time and money to finish it off

[cb650]

Ok about time we have pics of both your nitehawks in progress!!!!!!!

[davesee]

http://cosky0.tripod.com/

[coffee_brake]

Uh...these are not pretty bikes. Well the 650 will clean up well, it's just got decades of filth on it, but the 700 is in awful shape. It will need paint and lots of bodywork before it's fit to show anyone.

Thanks for the link to the manual, I already found it and printed off the pages I need right now. Between holiday stuff and a case of the sniffles, I haven't made it to the bike today. but I'm very excited about getting to it as soon as I can.

My Kawasaki Concours is my main wheels in the wintertime and I'm having a little trouble finding a short in it, so that's also taking most of my "bike" time too. sheesh, when it rains, it pours....

[fmctm1sw]

Uh...these are not pretty bikes.

Then they'll fit in just fine around here...  Look at some of the rats others have brought back to life around here.     

[coffee_brake]

I put fuel to the system tonight, and the Nighthawk is running and idling just fine.    Charging system is working and it comes off of choke in just a minute or so. Takes the throttle readily and sounds pretty good,

except...

I can hear a lot of cam chain rattle. Am I supposed to hear more cam chain rattle than I do with other bikes, like the DOHC Honda's I've ridden?

Most of the valves were pretty tight, and the timing had been moved so it was off just a little bit. And whoever moved it boogered up the screws so I'm glad I went through the rest of it to fix whatever else they did wrong. 

I'll spend the rest of my time tonight swapping in a good M/C and seeing what I need to get the calipers working. And the clutch cable is frozen in its sleeve so I'll try to bust that loose before buying a new one. Rear tire is hardly safe even for a test ride.
Thanks for all the help, it was much appreciated.

I'm anxious to ride it. Is sounds pretty cool, even stock! My first SOHC is alive....

[cb650]

Has anyone been in the top end?   They should be fairly quiet.  It is easy to get the tensioner in wrong and is a common problem.  Listen to the 650's on utube.  Half are in wrong.

[fmctm1sw]

Has anyone been in the top end?   They should be fairly quiet.  It is easy to get the tensioner in wrong and is a common problem.  Listen to the 650's on utube.  Half are in wrong.

I've noticed the 650 Custom I've been riding around is much noisier than the 650 Standard I've been working on.  I tried to do the cam chain adjustment on it months back and it got much worse before I was able to get it back to its "normal" state.  I may need to go into the head myself.  I've never had one out, does the top end come apart with the engine still in the frame like the small fours?