1984 CB700SC Nighthawk - first rebuild

Discussion in 'Old's Cool' started by Merfman, Nov 30, 2012.

  1. Merfman

    Merfman Trustin' my cape...

    Joined:
    Sep 11, 2009
    Oddometer:
    933
    Location:
    Colorado Springs
    What a week. Got back from a long road trip and on Weds night, slipped and fell on the blacktop while plowing snow and concussed myself. Again. #8.

    On Saturday, I had a chance to move parts around for a while. I started with replacing the fuel T on the carbs.
    [​IMG]

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    Once everything was put together, I checked to see if I had any leaks before installing he carbs.. no leaks! Yay!
    [​IMG]


    I noticed the throttle was a little gritty so I pulled it apart and cleaned everything up.
    Yea, it was a little gritty...
    [​IMG]

    A couple minutes later after applying some 200 grit and Scotchbrite.
    [​IMG]

    Before putting the carbs back on, I wanted to see if the gear selector switch was the problem with my lack of neutral light and indication on the gear readout. Using a DVM I found neutral on the switch, plugged it in and hit the ignition switch.
    Sorry 'bout the crappy pic but at least it's clear the gear position says "N" - sweet!
    [​IMG]

    It was about this time the concussion caught up with me and I needed a nap. ;)

    SILTHW: If I have gas in any kind of open container, no matter how careful I am, I WILL spill it and smell like gas the entire day.
    #41
  2. Merfman

    Merfman Trustin' my cape...

    Joined:
    Sep 11, 2009
    Oddometer:
    933
    Location:
    Colorado Springs
    I really haven't forgotten this bike, things have just been... let's use the word "hectic"

    Quick update - I'd ordered some wintergreen and found some Xylene locally. Got a chance over the weekend to soak one of the intake boots for 10 hours in a 70/30 mix of Xyelene/wintergreen. I'm very pleased to say that the soaked bits are much more flexible than the non-soaked bits. I'll try to get some video up soon but first I have to take my lovely wife diving for a week. Be back around the first of March and hopefully I can get things moving along at a better clip...
    #42
  3. Merfman

    Merfman Trustin' my cape...

    Joined:
    Sep 11, 2009
    Oddometer:
    933
    Location:
    Colorado Springs
    I'm back! :clap My beautiful wife and I took a mid-winter dive trip to Cozumel. Thought I'd share this vid:
    <object width="560" height="315"><param name="movie" value="http://www.youtube.com/v/eeufkHhppfQ?hl=en_US&amp;version=3"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/eeufkHhppfQ?hl=en_US&amp;version=3" type="application/x-shockwave-flash" width="560" height="315" allowscriptaccess="always" allowfullscreen="true"></embed></object>

    Once we got back and I got the remnants of snow removed from around the house, I got re-started on the Nighthawk.
    When I pulled the carbs apart, all the rubber was stiff and hard to move. I pulled the airbox apart in order to wrestle the carbs out and all the plastic was misshapen and stiff. I knew this was going to be a problem at reassembly. I'd been reading on the Nighthawk forums about varying success with Wintergreen and rubber renewal. Some were boiling the parts in wintergreen but the technique I decided to go with involved 70% Xylene and 30% Wintergreen and the Pickle Jar of Renewal (tm) :

    [​IMG]

    I soaked one of the intake boots for 12 hours, the results were nothing short of amazing IMHO. I soaked the other intake boot for 12 hours, then removed the short boots and soaked them all for 12 hours. I'm soooo glad I did this, it was easy enough that I was able to assemble/reassemble the carbs/boots about 5 times before finally remembering every detail.
    I'm amazed at how much difference this made in the flexibility. This is well worth the time for anyone dealing with stiff rubbers... just sayin. ;)

    With the boots renewed, I got the carbs all mounted up and the airbox snapped back together:
    [​IMG]

    That done, next up was the gear selector switch and oil sender connection. After trying to eyeball the slot and sensor for 45 minutes, I decided to just hook up the battery, temporarily attach the shifter and turn the switch until the neutral light came one. Put the bike on the centerstand and shifted the tranny in to neutral. Everything just snapped together after that... duh.

    Done, and replaced the clumsy phillips head screws with allens:
    [​IMG]

    Moving on, I replaced all the rusty allens in the various covers with new hardware:

    Ugly:
    [​IMG]

    Purty:
    [​IMG]

    Next up was to replace the tank, new fuel line and recovered seat:
    [​IMG]

    I shined up all the little cosmetic pieces and reassembled everything. Improving...
    [​IMG]

    Once I got everything put back together, I turned on the gas, hit the choke, held my breath
    and thumbed the start button... turned over about 7 times before it came back to life! Idles
    nicely albeit a little cold-blooded. No stutters, no misses, nothing.

    SILTHW - Assemble the airbox BEFORE seating the carbs.
    SILTHW - Pay attention/double-check throttle/choke cable routing.

    Next up is to get some tires, replace the plugs, and get the fork seals replaced...
    #43
  4. Merfman

    Merfman Trustin' my cape...

    Joined:
    Sep 11, 2009
    Oddometer:
    933
    Location:
    Colorado Springs
    I want to give a shout-out to our very own Vermin who now resides here in Colorado Springs. He has a new company called Nomad Trim (719-232-0947) and did an excellent job on the seat! He has some ideas for next time seats after seeing how this one fits on the bike. Give him a call for all your trim needs. You'll get excellent work and maybe, just maybe, a story or two... :lol3
    #44
  5. Merfman

    Merfman Trustin' my cape...

    Joined:
    Sep 11, 2009
    Oddometer:
    933
    Location:
    Colorado Springs
    My tires came in yesterday and snow is in the forecast... soooo.... I'll be pulling wheels for re-tread and forks for re-seal. I plan on a thorough inspection of everything obvious, any non-obvious type stuff I should inspect/clean/replace?
    #45
  6. Merfman

    Merfman Trustin' my cape...

    Joined:
    Sep 11, 2009
    Oddometer:
    933
    Location:
    Colorado Springs
    Tires are mounted but not replaced yet. Fork seal drivers arrived yesterday and a non-riding-friendly forecast is in place for the weekend. I put twin car horns on the Tenere' last weekend while waiting on the drivers so that project is done. Soo.... with any luck I'll get the bike roadworthy this weekend! Stay tuned...
    #46
  7. Merfman

    Merfman Trustin' my cape...

    Joined:
    Sep 11, 2009
    Oddometer:
    933
    Location:
    Colorado Springs
    When the day started, only one of these was marked off...
    [​IMG]

    My buddy Phil came over and supervised me while I tried to mark some items off the list. Little Yellow Pils by Oskar Blues were consumed and the day was a good one. Thanks Phil!

    Todays tasks included getting the fork seals replaced. I can't have it marking it's territory like this...
    [​IMG]

    And, the project box is down to one task...
    [​IMG]

    Under Phil's most excellent supervision, I was able to get the forks offs, disassembled, reassembled and awaiting the ATF I thought I already had...
    [​IMG]

    Once I had the forks to a point of "can't progress without a trip to the store", I re-pulled the tank so I could replace the plugs. Pretty easy job if you don't have gorilla hands. I have gorilla hands. Took a few more minutes and I then fired up the bike so I could warm it up and change the oil. Who thought that warming up the bike for "2-3 minutes" and putting the oil filter inside the heated cage known as headers, was a good idea? SILTHW - Headers stay hot for a long time. Got the oil done, re-fired the bike to check for leaks and all was good. I then took some time to clean up the front and rear wheels.

    [​IMG]

    I think I have about 2 hours of reassembly of various parts before I can take it out for it's first ride! Weather is supposed to be similar to today until mid-week and even then it's not looking good. Spring in Colorado! Hopefully I can get it all buttoned up next week and take it out for a short ride... stay tuned!
    #47
  8. Merfman

    Merfman Trustin' my cape...

    Joined:
    Sep 11, 2009
    Oddometer:
    933
    Location:
    Colorado Springs
    Yesterday was a beautiful day here in CO. My project box was empty and all that was left was the reassembly of everything...

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    Fired up the bike, ATGATT'ed up and headed down the street for my first ride... and ran out of gas at the end of the street. A short uphill push in full gear back to the garage and I discovered that when I'd readjusted the tank shortly before takeoff, I'd pulled the vacuum line off the intake. Reprimed the carbs, fired it up and headed out. Rode into town, gassed up, rode around some back streets and decided a freeway blast might help as well. Did about 15 miles at 70-75 and the bike was flawless. All told, put about 50 miles on the bike..

    Grabbed my camera and headed back out for a photo session. On a washboard road, I ran out of gas once again. Quick look and this time I see the vacuum line has popped off the petcock. Re-prime and it's running as new. Back to the house for a few final touches: 1) Replace vacuum line, 2) change final drive oil now that it was warm, 3) flush the brake fluid.

    The weather looks good enough for daily commuting next week so I should be able to sort out any additional little bothersome issues!

    I'm pretty pleased with the way it turned out!

    [​IMG]
    #48
  9. JWhitmore44

    JWhitmore44 pistolero

    Joined:
    Aug 7, 2006
    Oddometer:
    1,628
    Location:
    NW Kansas

    NICE! :thumb
    #49
  10. Speedo66

    Speedo66 Transient

    Joined:
    Jan 14, 2010
    Oddometer:
    6,971
    Location:
    Cin City, OH
    #50
  11. mike

    mike Long timer

    Joined:
    Mar 2, 2007
    Oddometer:
    3,408
    Location:
    Central Texas
    Great job on a great bike. owned an '84. loved it.
    #51
  12. Merfman

    Merfman Trustin' my cape...

    Joined:
    Sep 11, 2009
    Oddometer:
    933
    Location:
    Colorado Springs
    Put the bike up for sale last Friday. MUCH to my delight, my daughter decided she and her husband would love to have the bike! I could not be happier that this bike stays in the family!
    #52
  13. alk4life

    alk4life Wanna ride them all!

    Joined:
    Apr 23, 2013
    Oddometer:
    7
    Location:
    San Francisco
    I just went through an ordeal rebuilding the starter on my '84 CB700SC. The seal behind the front bushing failed and let in a ton of engine oil into the starter. The brushes broke apart and the armature fried. Here's a picture:

    http://i.imgur.com/mYbiCovh.jpg

    A rebuild kit and a new armature cost just slightly less than an aftermarket starter from Rick's Motorsports.

    The starter is very easy to access compared to some motorcycles so you may as well pull it and check for back and forth play in the shaft.
    #53