Topic: $300 1983 Night Hawk CB550SC - Full Rebuild Video Series

[n0fumar]

Hi all,

I picked up this bike about 2ish years ago and have been slowly tackling it.  I have an entire youtube series on it and am currently on Part 10 (just finished the top end of the engine).

Wanted to share it with you guys seeing as there aren't too many of these around.

https://www.youtube.com/watch?v=J0j5qD0VLP4&list=PL9bdKojgNyWqVslygfAdQWZvWQ3p8suG_  Here is a link to the current playlist

https://www.youtube.com/watch?v=GZm2T3Ai8y8 And here is a link to the most recent video I have done.

Hope you guys enjoy!  Feel free to ask any questions

[rb550four]

  This looks like loads of fun. I picked one of these up a year ago or so , cleaned the carbs and all that 3000 mile stuff we always do and I must say that these 550's are way faster than the cb's that I 'm used to. couldn't stand the riding position and the angle the riders wrist is in to operate the bar controls...easy remedy was to change those bars out,  so much better, positive control over all switches and no throttle fatigue in the wrist.
  My 550 , I suspect was in need of a lifter bleeding , but the PO had already buggered up most of the bolts on the top cover, most were snapped  off , some made it out and were replaced  others.....partially drilled out and new bolts actually siliconed in place... not much of a gasket seal there so it leaked a bit ....put it off to the side and lost interest in it. long story short picked up a 84'650 NH, same cradle, heavier frame , more progressive trans gears, larger carbs... going into the lighter 550 frame hopefully this spring, same top end and looks unmolested so far. Looking forward to doing it and watching your videos at the same time.

[n0fumar]

Haha loads of fun...maybe.  Lots of head scratching and four letter words for sure.

I actually have not gotten to ride this yet, so I'll have to let you know what it's like compared to my suzuki 800!

So for the engine with all the messed up bolts, what did you do with it?  I know you said you sat it to the side, but bleeding the tappets is actually a pretty easy job.  For the gasket and kerosene it's probably a $30 job and maybe 4 hours (but let's budget 8 since nothing ever goes as planned).

[rb550four]

 Yeah drilling and tapping out bolts isn't one of my favorite things to do especially when someone else has already tried it and f'ed them up even further, but I would do it if I didn't have the complete 650 donor, and I've always been happy to upgrade a cb550 frame with a cb650 engine and now's my chance to try it out on a nighthawk.
  The 650 was a mercy purchase, the bike was there looking really sad, the owner didn't look much better and it was a 45 min. drive to see it, it was cheap . I never tried to fire it up, so it's an unknown engine to me. I should at least pop the lid and see what has been happening with that extra cam and stuff in the top end. PO had it parked for a while , I might have had it parked longer than he did so I expect I'll be playin' with kerosene before all is said and done.
  Well, I can tell you that that 550 frame is a bit lighter than the 800 ( I'm guessing that you are talking Intruder) tires are thinner , and that will make some difference off the line. The shaft in the 550 won't pull  you sideways like the intruder shaft will off the line. The 550 is quick and straight all the way through the gears but , you'll find that you ran out of gears near top gear, it's real close to the last gear . Could have used an extra gear or a steeper overdrive gear, and that was always the problem with them, the excitement ran out in top gear . The 650 gearing is different than the 550,  a little steeper between gears and a better overdrive ratio if I remember correctly,  for me, that's the other reason for the swap into the lighter 550 frame. I just felt like I ran out of gears on the 550. That and a couple extra ponies pushing a lighter frame is always a good thing.
   Watch the bars on the first ride, they feel weird and unstable. I swapped them immediately to something similar to the old cb 550 bars only lower. Then let the fork tubes ride 1 in. higher than the tree. It felt allot better and more stable after that.
 

[n0fumar]

Hi all!  Been a while since I made an update on this, but wanted to provide some more videos.

In this episode, I tackled the painting of the frame (rattle cans), brake rotor, brake caliper, and fuel petcock!

[n0fumar]

Haha well...here we are again like 9 months later.  I really gotta work on doing updates faster.

Finally got the engine in the bike. Made it much easier to lay the engine on it's side and then drop the frame on top of it.

[n0fumar]

Here we go again...

about 2 years alter and I'm finally actually installing parts into the bike.  I've got the rear suspension, rear tire, front suspension, front tires, and some other odds and ends up top.  Trying to keep the motivation going for the project, hope you guys enjoy!

[Alan F.]

Nice, I'll bet you get a warmer reception here than on the NH forums. Thanks for posting.

[n0fumar]

Thanks!  It's definitely been a project...

What do you mean by the NH forums?

[Alan F.]

https://nighthawk-forums.com/

Not always the friendliest bunch toward Nighthawks with one cam, older than 1983 or younger than 2003, or displacements under 700cc.

Their search function works though, and there is a good amount of info for 250, 450, 550, 650, 700 and 750 Nighthawks. But I understand the really good info was lost years ago when a previous site was hacked, bummer.

[n0fumar]

Well that's a huge bummer, was thinking of posting over there as well.

Either way, thanks for the heads up.

Also, would my bike technically be a dual cam setup?  It's got two cam shafts up top (one for exhaust and one for intake I believe).

[Alan F.]

Go ahead & post over there I don't mean to poop on their forum, they just don't run things the same as some other forums.

[SOHC4 Cafe Racer Fan]

Well that's a huge bummer, was thinking of posting over there as well.

Either way, thanks for the heads up.

Also, would my bike technically be a dual cam setup?  It's got two cam shafts up top (one for exhaust and one for intake I believe).

I believe your bike is DOHC - from 1983 onward.  That said, we like following projects and there are many similarities.

[n0fumar]

Yeah, I mean it's relatively similar.  I'd argue good enough for government work lol

Here is the next video.  Installed the carbs, swapped out clutch materials, and did the exhaust.  The carbs absolutely sucked, I've never seen a worse mounting design in my life. Very glad to be done with that.  Unfortunately, also snapped off an exhaust stud.  Book said 20 ft-lbs for tightening torque, but I never got there.  Should've used my tried and true "this doesn't look like 20 ft-lbs" mindset, but I was too trusting of the manual.  Ugh.

[Alan F.]

Yes we've got some aftermarket manuals that show a 6mm bolt or stud at 20ft-lbs too, thanks Haynes! Factory Service Manuals can be found & downloaded for free.

There really is no need to torque an exhaust nut, bolt or stud, go by feel if you can and if it leaks when you start it up give it a quarter turn at a time until a seal is made, then give it another quarter turn & put it on your 300 mile checklist.

Looking good!

Re: carb mounting
Lots of Hondas of that era required you to remove the rear axle & roll the rear wheel back a foot or so, remove all of the airbox mounting bolts & slide the airbox backward all to make room for installing the carbs. You can get away with just loosening the airbox and shoving it back, but yes its still pretty tough.

[n0fumar]

Just got done with Part 15.  Now all the electronics are installed (wiring harness was a bit difficult).  I'll also add in that the footpegs were quite difficult to work around, specifically the right footpeg.  Something about the rear brake pedal was giving me so many issues getting the spring aligned and happy.

[n0fumar]

The gas tank needed a fair amount of filler / glazing compound to get it right. Uote literally took hours of sanding and re-sanding and re-re-sansinf to look good.

And then it fell off the table and I had to re-do it all over again.

The clear coat looked absolutely fantastic after drying. I went to wet sand and buff / polish after and I'm not really getting that good of a shine out of it anymore which is surprising. Maybe I didn't polish enough? Maybe my polisher just isn't good enough? Not sure.

Clutch and brake master cylinders were disgusting. And bleeding them was no easy task. Had to use a mightyvac to bleed them just to get anything to happen. That thing has saved me more times than I'd care to admit.

Should be getting it started in the next episode!

[n0fumar]

I'll just leave this here and not spoil anything.  Hope you guys enjoy this one!

[grcamna2]

That's quite a big project for you to take-on for the first time,all by yourself.
The starter motor doesn't sound very healthy;I'd be looking for a good cond. low-mileage starter if it was mine.The new? battery needs to be brought up to about 12.9vts(AGM) or full charge with all 4/5 balls floating equally using a mini hydrometer on all 6 cells,if it's a standard battery.A 'hot'/fully charged battery is required to start your bike well. 
I didn't view all the videos:did you need to do the pistons/rings & cylinders also ?
What brand/models are those other sportbikes behind the open garage door ? 

Edit:I noticed when you try starting that bike,that you're opening the throttle twist grip:doing that will usually defeat the carb. enrichener jets and prevent fuel from flowing 'only' from the choke/enrichers in each carb.
I sometimes do that,but only with a very light touch 'feather' on the throttle hand;when the throttle butterflies are more closed for starting,it will create more vacuum internally to pull fresh fuel/mixture up into the carb throats thereby accomplishing a full choke mixture.

[n0fumar]

It was an intense project, I can't even begin to tell you how much work it was.  Getting everything taken off, sorted, then moved and had to re-find everything, gosh what a mess...

Speaking of the starter not sounding good...

I had a hunch that something was up and it wasn't very happy.  Sounded like it wasn't catching all the time and was grinding almost.  I took it off (let the battery charge for a day or so) and opened up the back.  Oh...my...god.  I think the brushes basically turned to dust haha.  Take a look at the pictures below.  After cleaning everything up it sounds much nicer.  I ordered some new brushes for it, just need to take it back off.  It seems to be turning over much happier.

https://imgur.com/a/wBGT9Ip

[n0fumar]

Side note, here is a weird bug I'm having with the choke on the bike.  Maybe you can add your thoughts?  This is copy / pasted from another forum.

Hi all,



I'm having a bit of a tough time figuring this one out, and any advice would be greatly appreciated.



To preface this, the bike has been completely rebuilt, and the carbs have been overhauled probably 3 or 4 times.  By that, I mean new o-rings, all passages cleaned and all jets are open and clean.  I have NOT changed any jets or tried other configurations, as apparently this carb is not good with rejetting.



I will also say the bike does run, but it takes forever to start.  Once it finally starts up, it's happy as can be and has fantastic throttle response and no issue at any RPM throughout the range.



So onto the problem I have;



I feel like the choke does absolutely nothing for this bike in terms of helping me start.  This is not a typical choke where it closes the butterfly valves or restricts airflow.  It is apparently "a "bystarter" system in which the choke lever opens a valve rather than closing a butterfly in the venturi area as on many carburetors.  In the Open position, the slow jet discharges a stream of fuel into the carburetor venturi to richen the mixture when the engine is cold" (right from the manual).  I've had more success starting the bike without the choke than with the choke.  And when running the bike, when engaging the choke, the bike just starts to sputter and die (make sure audio is on.  In this video just be mindful I've since rebuilt the starter, so that odd whining sound is gone).This is a little counter-intuitive to what I'm used to, as on all my other bikes when you engage the choke the bike revs much higher.  Again, different choke design so I'm not entirely sure.

https://imgur.com/7x8g6U9



Sometimes I wind up having to crank for 2-3 minutes (in 5 second bursts) before I get any sort of sputter out of the engine, and then I have to hold the throttle open a bit to get the RPM high enough for it to be happy.  About 10-15 seconds of this and it's finally happy.



So here is what I've done to try and diagnose some of this stuff.



Completely stripped and cleaned / rebuilt the carbs.  This includes removing the choke parts and cleaning out all passageways.  Floats are set to correct levels.
Replaced all o-rings for the carb setup
Verified each bowl is getting gas
Set pilot screws to factory settings (I think it's 2 1/4 turns out from freshly seated)
Set sync screws as closely as I could to be equal to each other.  I used a caliper and got them probably within 0.1mm of each other
Always tried first starts with a freshly charged, 2 year old battery
Rebuilt starter motor (thought something was wrong and it wasn't spinning fast enough, can't tell if this helped)
Verified each spark plug has good, strong spark
Finger tested that each cylinder has good compression (haven't gotten a gauge on, but I don't think this would be an issue anyway)
Verified no vacuum leaks by spraying carb cleaner around the boots (no changes in RPM)
The fuel petcock is clean and works properly
New gas (less than 2 weeks old)
Gas tank is clean inside
Pulled off and reinstalled the carbs more times than I would like to admit.  I hate these boots with a burning passion
Kind of at my witt's end here, so if there are any mechanics with some ideas / thoughts on what might help, I'd love to hear anything!

Kind of at my witt's end here, so if there are any mechanics with some ideas / thoughts on what might help, I'd love to hear anything!

[grcamna2]

n0fumar,I believe there is a small brass tube at the bottom of each carb bowl mating surface that needs to be completely cleared-out;there is a small hole at the bottom that allows fuel to be sucked up into that "bystarter" you mentioned and that is probably clogged on those carbs.
The carb bowls also each have a small 'well' for that little starter enrichener brass tube and there's a small hole at the base of that 'well' that lets the fuel flow into it to feed the chokes:that little hole needs to be cleaned out with a small guitar 'E' string type wire also.

The starter servicing is very necessary on that one,eh?