Hey all-
Post #1 in my attempts to get a project bike running. 
So, the background.....  I recenty laid my hands on a 1985 CB650SC Nighthawk.  I was told it was not running when I received it.  It had no battery.  The guy I got it from had received it as a project 4 years ago from a neighbor.  When he received it, it was not running largely due to a lack of a functional battery.  He intended to play with it, get it running.  Well, he never touched it...  A couple weeks ago i met him.  He just wanted the bike to go away.  It had been sitting in his driveway for the past 4 years and he figured he was never going to touch it.  He has an SV650, why bother.....  So, for a 6 pack of beer and $10 for gas, the bike has ended up in my garage....
Today ,we blew a bit of dust off the bike and got started on trying to get it running.  Today's big goal, the engine!  I had the help of a friend today who has done a similar mission on a 198x Honda Sabre 750, and no service manual.    We popped off the gas tank and drained it.  Shockingly, the gas in it was pretty particulate free and smelled pretty normal.  We checked the oil appearance and level.  The oil also didn't look that bad and was high, if anything.  Next, we pooped out all the spark plugs and replaced them with new ones.  Also gave the bike a quick shot of WD40 into each cylinder.  We put the bike into 6th and hand cranked the engine a few times just to make sure that each cylinder moved and to give them a little lube to start off.  Next, we then fired the bike up!  It took several times to reestablish a vacuum and get gasoline into the carbs.  We got it started!  So, good start...  Only one problem....  No firing in cylinder 2.  No heat on the exhaust pipe.  We drained each of the carbs a bit to make sure that fuel was getting into each carb.  Came back with an interesting result...  Carbs 1 and 4 drained with no issues...  Carbs 2 and 3 did not until we almost unscrewed the drain screw completely!  Yup, dirty carbs, everyone's favorite topic.....
So, we popped the carbs out of position...  Took us about 20 minutes of wrestling with the boots, swearing profusely and a little more wrestling before we got them off.  The piston of carb 2 was definitely a bit sticky.  We hoped that was the answer to our problem.  We checked the vacuum seal on the top of carb 2, looked fine.  We cleaned the bowls of all four carbs.  The bottoms of 2 and 3 were completely blocked up.  Now, not a problem.  We also checked the two jets that were removable, cleaned them up.  I have to say that there is no better way to understand carbs (or anything) like taking it apart and putting it back together.  I had read about carbs, see hand-drawn photos, but nothing beats taking it apart and cleaning it....  A lot of work, but I learned a ton...
So, we wrestled the carbs back into place and fired the bike up again.  At idle, no change in cylinder 2.  It did not get warm at all.....  My friend started giving the bike gas and it was dying off...  Kept doing that and it slowly started responding...  Ripped on it a few more times and it was responding decently.  We got it idling at a relatively low level of choke.  We noticed at this point that cylinder 2 was getting a bit warm!  It did not get as warm as the other 3, but definitely warmer.  I am now letting the bike cool down before checking it again to see if running the bike at slightly higher RPM helped....  Not a bad first day on the bike!!!
Our current thoughts are that the idle jet may be blocked up in cylinder 2.  Hopefully it will clean itself up in time.  It is not really removable and needs to be cleaned by sonication.  We are having trouble figuring out why it's not running.  It gets spark, it gets fuel (now gas drains out easily), it gets air as the rest of the cylinders run beautifully.  Compression is one idea....  Scratch, wanna come play some time?  I have a car too! 
So...  where does that leave me...
The laundry list of things to do...
1.  Change the brake and clutch fluid.  The bike has a hydraulic clutch.  Very simple task, just needs to be attacked.  I have the fluid, we just chose t oclean the carbs first.
2.  Check the oil in the drivetrain.  The Nighthawk is a shaft drive.  At least initially I just want to make sure it has the proper level of oil in it.
3.  The front fork seals are totally done in.  I will remove the front end f the bike and bring it into a shop and have them replace the fork seals and oil....  I could prolly do it, but I think I'm not in the mood....
4.  New Tires!!!  The tires on this bike are totally done in...  Definitely need replacement.
All the electrics are running well.  The turn signals work, the brake light works and the dashboard looks like it is functional.  If you have never seen the dashboard on these old Hondas, they are a trip....
Well, I think I've rambled on enough.  I'll keep this updated as we  do more!  Comments and suggestions are always enjoyed and appreciated.

Quote from: jbeaber on August 06, 2006, 07:28:22 PM
At idle, no change in cylinder 2.  It did not get warm at all.....  My friend started giving the bike gas and it was dying off...  Kept doing that and it slowly started responding...  Ripped on it a few more times and it was responding decently.  We got it idling at a relatively low level of choke.  We noticed at this point that cylinder 2 was getting a bit warm!  It did not get as warm as the other 3, but definitely warmer.  I am now letting the bike cool down before checking it again to see if running the bike at slightly higher RPM helped....  Not a bad first day on the bike!!!
Our current thoughts are that the idle jet may be blocked up in cylinder 2.  Hopefully it will clean itself up in time.  It is not really removable and needs to be cleaned by sonication.  We are having trouble figuring out why it's not running.  It gets spark, it gets fuel (now gas drains out easily), it gets air as the rest of the cylinders run beautifully.  Compression is one idea....  Scratch, wanna come play some time?  I have a car too! 

It's still not getting enough gas through the stopped up idle circuit.  Pull those carbs off again, and clean No.2 properly.  Clip one hair off of a soft brass bristle brush and poke that around in the idle circuit holes.  Trace the passages (tubes/tunnels/tunnel bulges), and clean the air jet, too.  If the air jet is clogged, no amount of vacuum is going to draw gas out of that circuit (no flow).

Check compression the lazy way.  First take all of the sparkplugs out and use your thumb over the No.2 plug hole to feel for pressure.  Or, squirt a teaspoon of oil into the cylinder and replace all the sparkplugs to see if compression increases.

Valve adjustment may be needed, if that doesn't improve.  Oh wait, does this bike have hydralic adjusted valves?  In which case, nevermind...unless, the oil pressure to that adjuster isn't getting there because the oil passage is blocked (kinda doubtful (use Castrol GTX 20w50)).

Quote from: jbeaber on August 06, 2006, 07:28:22 PM
3.  The front fork seals are totally done in.  I will remove the front end of the bike and bring it into a shop and have them replace the fork seals and oil...  I could prolly do it, but I think I'm not in the mood...

Think of the money.

Sadly, cylinder two has not been cleaned out enough....  So, I may wrestle the carbs off again to see if we can get the hole cleaned.  I individually cleaned each jet of the four carbs.  From what i learned today there are three.  The largest and the mid are cleaned, the third cannot be removed.  Would running carb cleaner through potentially help with this issue?

usually theyre all removeable, (jets), if not remove all the plastic and rubber from carb and soak each carb in carb cleaner overnight or at least 24 hours. should take care of it, and stab each passage witha small guitar string

So, last night was the second attack on the mysterious non-functioning cylinder.  Just to make sure, I switched the spark plugswith another cylinder.  No change.  Then I removed the spark plug and did a compression test that way.  It seemed to have comparable compression to the cylinder next to it.Then, starting to check the valves, I just ran the bike for about 20 minutes.  Today i will change the oil and repeat to see if the hydraulic valves are the issue.  I'm not sure if this means anything, but after 5-10 minutes, the pipe for that cylinder is hot.  not as hot as the ones next to it, but definitely hot.

Wow, been a while since I updated this and quite a bit has been done to the bike.  It took me a while to figure out the case of the mysterious non-functioning cylinder.  We performed a variety of interesting tests to try to figure out the problem.  We checked to see if there was spark on all the cylinders and to see that the spark was equivalent in all four cylinders.  They looked pretty good.  We also learned a bit about the coils.  If a coil isn't working, it takes out two cylinders.  So, no coil problem.  We also switched the cables between it and another cylinder, the cables to the spark plug were fine.  So, no spark issue.  Air also wasn't a problem, the other cylinders worked fine.  Compression was another thought.  Using the infamous finger test, it seemed equivalent to the other cylinders.  My father-in-law gave me a compression gauge, but the thread was too big, designed for a car.  The CB650SC has hydraulic valves.  I changed the oil just in case that was a factor.  After all of this, still no happiness.  So, then I removed the boot from the air filter to the carb (for at least the second time) and switched my focus to the carb.  i sprayed some carb cleaner in a few times, no major change.  I drained the fuel from the carb of the non-funtioning cylinder and the one next to it to compare the volume of gas; they were identical.  We also noticed that the spark plug wasa little wet.  Now, one observation that did give me the final clue as to what was really wrong, is that when I sprayed carb cleaner into the cylinder while the bike, it did spike the revs.  This indicated that the cylinder did seem to be working.  So, I worked the carb over quitea bit more with the carb cleaner with the throttle open.  It started up!  I added some carb cleaner to the fuel so that it will continue working on the carb.  In the mean time I have changed the clutch fluid and brake fluid.  Next a friend will help me attack the fork seals.  Then, the final major issue will be getting new tires...  The project may be running in the not too distant future!!!

I wondered why you'd been so vewwy, veww qwiet lately....now we know! When do we get to see pics!? 

Well, here is a photo of the man cave....  My bike on the left, the wife's on the right and the project in front....

w00t!!! That's a beautiful stable! 

x

I'll enjoy any excuse to show off my man cave!!!  It's a bit more cluttered right now, but will soon get back to normal.  My father-in-law stopped by a couple weeks ago with a healthy supply of tools for me.  The goal is to get this bike running, use it through the rainy northern California winter, then sell it in the spring so I can grab a nice little 70's cafe racer.  Also, use the things I have learned getitng this bike running on that little 70's bike.  It has already helped me learn things that have helped with the SV and the Daytona.  Soon I'll have a propane jet and lighter rigged up to that main exhaust hole on the 675...  Just give me time....

Well, an update...  Been a few weeks.  I have had some success in getting the number 2 carb cleaned, but it still isn't perfect.  I know that the idle jet is the problem.  If I have the bike idling on the three cylinders and add carb cleaner to #2, the revs do spike.  I had it running on all four for a bit, but then left the bike alone for a few weeks.  I just need to get in there and clean it for a bit.
The nighthawk has a hydraulic clutch.  It has a master cylinder on the handlebars very similar to a brake cylinder.  It had a small leak around the sight glass.  I found a pretty good sealant (Seal All) and applied it this weekend.  It seems like it is resistant to brake fluid and has done the trick.  So, hopefully I have sealed up that minor problem.
I made my first trip in my life to Harbor Freight this weekend and bought lots of fun toys, a bench vise, allen wrench adapters for a socket wrench, some lights, telescopic magnetic grab bars, tie downs....  Man cave is greatly improved.
That leaves me with two other issues to deal with.  The first is easy, new tires.  I have shopped around a bit.  On a bike like this, any of the tires produced by a major manufacturer will do the trick nicely.  I took both wheels off this weekend and we will be getting new tires for it this weekend.
The next issue is for seals....  So, the wheel is off, fender removed.  I have removed both fork tubes (torque wrench and allen wrench socket wrenches absolutely needed).  The left tube has been partially disasembled.  The oil has been drained and the top cap and bottom cap removed.  I have also removed the dust boots.  Once getting to this point I discovered I need snap ring pliers to remove a snap ring holding the fork seal in place.  So, grabbing those today then I will continue fork seal work.  Thus far it hasn't been bad.  Keep your fingers crossed.  any comments or suggestions on fork seal changing would be appreciated...

Busy day in the man cave...  Changed the oil and oil filters in both my Daytona 675 and my wife's SV650.  Then attacked the project bike.  I found a great explanation on how to change fork seals on the Nighthawk.  Easily got the fork apart.  It took me a while to figure out snap ring pliers, but got the circlips out.  Then just slam the fork seals against the fork tube til they come out.  Cleaned everything up and sanded some rust off of the inner fork tube.  Then slide it all back together again, fill it up with new fork oil and put it all back together.  The first one took a while, just figuring everything out, second was quick and much easier.  It is a messy job, but, beyond the snap ring pliers and a little bit of plactic tubing, didn't require any unusual tools.  i've heard that you need a special tool or a broom handle to do the GS500.  Now I just need to put the fork tubes back on, add a little air and put both wheels back on.  We got the tires changed on both the SV and the Nighthawk last week.  Project bike is definitely accomplishing its goal.  I am learning a lot, having fun and will soon have a bike out of it!  I need to go in and clean that one carb out with a little piece of wire to clear up the idle jet, and change the shaft oil.  Then we'll see what happens when i try to put it on the road!

Wow, sounds like fun!  Wish I lived close to the Man Cave, I'd bring a 12 of imported beer if you'd just let me watch!

-Turd.

Well, a few more weeks pass...  Life i nthe man cave is good.  So, shortly after getting the fork tubes back together and back on the bike, I decided to find out if the bike would actually run on the road or not.  So, finished putting the wheels on, armored up just in case something decided to blow up and took the nighthawk on to the road.  As far as I know, this was the first time the bike had been on the road for at least 5 years.  Got it started and on the road.  It was making a rattling noise from the engine for the first couple miles, but sorted itself out quickly.  we were thinking this could have been from oil getting into places in the engine where oil hadn't been in a long time.  I rode it for about 5 miles around my neighborhood and, man, once you give that in line 4 a bit of gas, it really can take off.  The funniest part about this trip occurred right when I got moving.  I went to put my feet on the pegs...  and missed.  I'm used to riding either an SV650 or Daytona 675.  Very different peg position.  I basically tried to put my feet on the rear pegs...  Whoops! 
So, after about five miles of riding I decided it was time to head into the garage.  A couple crossed in front of my garage as I was about to head in.  While waiting for them, I stalled out.  The bike would not restart, lights dimmed heavily suggesting the bike didn't have the charge to get going again.  also, i then noticed that a fork seal was not holding...  So, more things to do. 
I got a replacement fork seal and have since replaced it.  The new one looks like it is holding better, but the bike hasn't been on the road yet.  The electrical issue took a few days to figure out.  I had the bettery tested and it came out fine in a load test and over all check.  Next I checked the voltage while the bike was running at 3-4K RPM and it was at 14.4 V, pretty much perfect.  I checked the charge on the battery afterwards, 12.7...  still good....  Next I popped the starter motor off, on the suggestion of a guy from another forum.  After dumping out quite a lot of carbon, I took a look at the brushes (BTW, brushes?  no, completely inappropriate name.  Small hunk of metal...  much more appropriate name...).  One of them fell apart in my hands, the block split releasing the wire connecting it to the electrical system.  From what I have been told, this could explain my electrical problem.  So, ordered them up before Thanksgiving and I'm waiting for them to come in.  In the mean time I also went into one carbeurator that was still giving me problems.  It wasn't running on idle, but worked great at higher RPM.  On the recommendation of my mechanic, I went into the idle jet with one 'hair' of a wire brush and gently worked it into the jet.  I definitely encountered resistance.  I then gave it a good treatment with carb cleaner.  Won't know how well that worked until I reassemble the starter motor. 
The bike is all together except for the starter motor.  I'm hoping to get the new brushes in the next day or so, dress the commutator and get it all back together.  Then comes the next test ride..... 

Awesome.  Waiting for the next post.

good read.

Thanks...  It has been an interesting an educational project so far.  I had pretty much no experience in mechanics when i started.  Now I have a lot more understanding, many more tools and have had a lot of fun beating on this bike.  These old bikes that have been sitting are puzzles...  Just have to figure out what is wrong, which can definitely be a challenge at times.  also i hope to be able to do more and more of my own work in time....  I also may get bored and evenutally try to mod the bike into a streetfighter    I gues i would have to remove the cruiser pegs first....

Yes yes.  Street fighter.  Look up Project Momba in Sport Rider or Cycle World. 

A dude on a nighthawk forum is working on one.....
Drop handle bars
pulled off all the plastics
chopped 5 inches off the frame in the back and a few inches off the seat
not pictured, but now has dual headlights on
working on replacing the speedo

A before photo of the bike in general



And where he was at last week