• 1984 Nighthawk S models had a problem with oil leakage from the left crankshaft seal. Honda issued a Service Bulletin to dealers on this. The first fix is to replace the crank seal, which requires splitting the crankcases! However, if this doesn't work, the bulletin recommends installing the 1985 crankcases, which no longer use a crank seal. The cases are easily recognized because the pulser coil wires come out near the top of the cases (like the later Nighthawk 750) instead of the bottom.

  I've owned two 1984 models and both had the oil leak problem. I fixed my first one with a new seal. However,my current one required crankcases.

  • Steve

• 750S Starters - I bought a used starter-- paid $150.00 Canadian ($108.00 US Aprox.) from M&M Cycle Supplies in PEI, Canada. M&M's number is 902-651-2259, and they are not on line. I got there number from a 750s owner linked to your page. They were great to deal with (called me three times to make sure things where ok and to let me know it was checked, shipped and when I could expect it) but they don't even own a computer, but they are getting one soon. The 700S and the 750S both use the same Mitsuba SM-8 12V starter motor. I picked up a used official Honda Shop Manual for the CB700SC and it confirms this information. I'm told that everything is the same, only the engine bore and stroke are larger. But I'm not 100% sure of that.
•  Another Starter Source - Milwaukee Cycle Salvage has them for reasonable prices. Check them out!
• Question & Answer from rec.motorcycles:
  • I need help. The gear that the starter engages is slipping- and the motor isn't turning as a result. Is there a starter-clutch there or am I missing a gear? I've spun the starter outside the case and it's going the right direction. All the gear teeth look good. What is malfunctioning on my motorcycle?
    • According to my shop manual, remove the ENTIRE starter unit and check it. There's planetary gears in the end of it. Check to make sure the ENTIRE unit turns freely. If the drive gears are slipping, the starter will freewheel and spin, not stall. Assuming that the starter unit is functioning properly, jump out the solenoid with a screwdriver and see if you can hot line the battery direct to the starter. If it starts, the solenoid's bad. If that doesn't work, and the lights go dim on the bike, jump it with a beefy set of jumper cables to a car. If it starts then, then replace the battery (after checking the hot and ground connections.

• Contributed by Fred B.
  • I have an 84 Nighthawk 700s that I really enjoy riding. I used to have a 75 Honda 750SS that was fun but the Nighthawk is better. I purchased the bike used and the previous owner did not know a whole lot about the bike because he bought it from a friend who needed some cash. The bike had a Vance & Hines megaphone pipe on it and was jetted very, very rich. The thing was so rich I thought it was a diesel! I contacted V & H for some advice and they were very helpful. They gave me info to use as a starting point and it was on the money. I recently decided to take the leap and buy a K & N air filter for the bike. I have used them on other bikes and cars and have been very pleased with the performance. This time was the exception. The filter is not exactly a drop in as they claim. It is really one of their generic tapered round filters that they made an adapter plate for. To use the filter the stock cover has to be removed, flipped over and reversed, the snorkel removed and switched around, and then all screwed back together. What a joke! They claim no jetting changes are required which may work for stock pipes but not an after market model. The bike ran so bad I thought I was going to have to push it home once. I was not ready to give up since the thing cost $50.00 dollars. I contacted V&H again and they gave me some more recommendations that worked! They have been a great help and they actually read their E-mail! K & N never responded to my request and neither did Factory.
  • Update from Fred B. I have an update on my jetting problems on my 84 700SC with the K&N air filter. If you recall I have a V&H street megaphone pipe that I was trying to sort out the jetting problems. After living with the jetting for a few days it became apparent that the jetting was still not right. I packed up the tail trunk with tools, plugs, gloves, manual, and went for a ride down a lightly traveled country road to get an accurate plug reading. I ran the bike at the rpm range that I was have problems with for about two miles, pulled in the clutch, hit the kill switch, and coasted to a stop. I pulled out the plugs and much to my surprise they where white(lean). All this time I thought it was rich! I went home, raised the needles to richen the low to mid range, and went back out. This time the plugs were fouled and it still did not run any better. The one thing I did note was that the point at which the missing(?) occured had shifted up. At this point I was really baffled but I was determined not to let the bike beat me. I tried each gear under similar conditions and the higher the gear the lower the rpm range the problem occured. I went back home and evaluated the situation with a few cold ones and came to the conclusion that the bike was not getting enough fuel. After a few more cold ones I determined that the only two things that I changed were the jets and the air filter. I was sure that I had the correct jets but was not too sure about the air filter. The next day(I had one too many cold ones to go back out) I put the original filter back in and the bike rocked! No flat spots, no white plugs, no black plugs, just a solid kick in the low and mid range with a little more on top. What was happening was the K&N filter was flowing so much air the bike could not deliver enough fuel. All the time I spent on working on the bike has taken its toll. I just don't have the determination(or cash) to go through and try to re-jet the motor to work with the K&N filter. Taking off the carbs is a real pain and very time consuming. If I was in the market for another 700SC I would make sure it had stock pipes.

    Fred B.

• Contributed by Fred B.
  • I use a Fram PH6811 oil filter instead of the Honda filter and it works great and costs about one third as much. The same filter will also fit an 84' 500 Interceptor and V65 Saber. PH6811 is sized for some import cars so it is rather small but not smaller than the stock filter. Also, it takes an 80mm filter wrench (the type that fits on the end) and can be removed between a header without removing the pipes. However, the pipes on a V&H street megaphone must be loosened and the muffler end must be removed to get to the oil drain plug on the engine. The plug can be loosened with pipe in place but not removed.

   

• Question & Answers from rec.motorcycles:
  • What's the easiest way to get the oil filter off one of these. Thanks to all who responded to my early message. I appreciate it and all the comments were very helpful.
    • I have an 85 as well, but, from the '84 CB700SC Honda Shop Manual: "Loosen the oil filter with a filter wrench and extension bar and remove it between the No.4 exhaust pipe and the frame." I usually get a small automotive wrench (metal band kind) in there to loosen the filter. Sometimes you have to give it a tug to get it past the exhaust. Looking at the bike from the front, I believe that you want to take it out on the left side.
    • On my '84 Nighthawk 700S, there's just no way to get a standard oil filter wrench onto the filter. The exhaust headers are juuuust too close together -- I can't even slip on a low-profile, cup-type wrench. I always have to take the headers off (bleah). I know that sounds like it can't be right, but I've heard the same from a number of other riders. Supposedly, Honda makes a special filter wrench that will fit. You might ask a dealer. My comment: I wonder who's right??
    • Take a new filter to Pep Boys, Western Auto, etc. In the section with the oils and filters there'll be a section with oil filter caps (or cap-type wrenches). Find a cap that fits and make sure you have the right ratchet to fit the cap (usually 1/4" drive) and a 6" extension bar. There's plenty of room to slide the cap in between the header pipe and the crankcase. Then you just use the ratchet to remove. The caps cost from $5 to $10 but it's much easier than swearing and ultimately experiencing an EMF (Episode of Maximum Frustration). When the filter's loose slide (actually gently force) it out between the crankcase and the #4 header pipe (on the brake side of the bike).
  • The Final Word In the shop & owners manual, if you look closely, the oil filter cap wrench has one third of the top removed to access the lack of space between the pipes and the filter. I have seen one at a Honda dealer to confirm this fact. My Personal tip: I took a filter to an auto supply shop, found a cast aluminum cap filter that fit (manf. by D & F MOLD, Bridgman, MI.- 80 mm, w/16 flat edges) and hacksawed off the bottom third of the top, leaving the entire band (circumference) intact. Cheaper than buying one from a Honda dealer and works like a charm.
  • Another Solution (from Tom Marks):
    • I think that I originally saw this idea in Motorcyclist or Cycle World. What I use to snug up and/or loosen my oil filter is an old belt. I insert the belt through the buckle,just like if I was wearing it. Then just slip it over the oil filter and double it back on itself to assure the necessary amount of friction. It will loosen or snug up the filter just fine. Best of all it was free. I just used an old worn out belt that I don't wear anymore.
  • And the Honda solution:
    • I was checking out your web site and observed the problems that people were describing with the removing the oil filter on 84-86 Nighthawk S models. I would suggest that you recommend using the Honda supplied oil filter wrench. The tool makes effortless work out of removing the oil filter from a Nighthawk S. I have a 1984 model and the wrench works wonderfully! It fits easily on the filter without removing the head pipes!

      I work for American Honda and have been using this wrench for years. It fits Honda V-4's, CB700SC's, Honda Accords, Civics, Generators, and other Honda products. I'm not sure of the price, but I'm sure it's reasonable. The Honda part number is 07912-6110001 and the tool is available at any Honda Motorcycle, Power Equipment, or Automobile dealer. The dealer may have to special order it, but it's worth the wait. Hope this information is useful.

      Steve F.

  ---

   Tires & Wheels

• Contributed by Fred B.
  • I put a set of Bridgestone BT-17's on my bike and it was like adding power steering. Great tires!

Back to Nighthawk Maintenance page

Back to Nighthawk Main page