550-4 won't rev

Discussion in 'Motorcycle Technical Discussion' started by Jim, Apr 24, 2004.

  1. Jim

    Jim Guest

    1983 cb550sc runs great to 5000 rpm then cuts right out. It comes back
    to life at 4000 or so. Don't know you've a problem if you avoid
    revving it past 4500.

    I'm thinking maybe ignition module or pickup. Anybody got any advise
    on how to test these parts or maybe something else.

    Thanks,

    Jim
     
    Jim, Apr 24, 2004
    #1
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  2. Jim

    Steve Guest

    I had a problem like this with my 82 Honda 900 custom. One of the coils
    had developed a split down the bottom of it and when i replaced them
    with Accel coils there was no problem after that.
    Steve!
     
    Steve, Apr 25, 2004
    #2
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  3. If it's a CB550, they didn't have electronic ignition.

    1983 - hmmmm: is this the 16-valve thing? The CBX550 we called it in the
    UK, although we never got a Custom variant....

    Sound slike ignition advance problem, but hard to say without knowing
    what bike it is. If it's CB550 and points ignition, then it definitely
    isn't a module problem.
     
    The Older Gentleman, Apr 25, 2004
    #3
  4. Jim

    Jim Guest

    Yeah, it's the 16 valve 4 cylinder thing, known here as a Nighthawk.
    It's got a module. Its also got two coils and an arrangement hooking
    up the plugs I've never before seen and find unusual. Two plugs fire
    together allowing a coil to be in series with two plugs. Ive
    previously only been aware of hookups in which one side of the high
    tension winding is grounded and the other goes to a plug but in this
    case one end of the coil goes to a plug and the other end goes to
    another plug. The remaining two plugs are connected the same way to a
    second coil. Both coils connect to the module.
     
    Jim, Apr 25, 2004
    #4
  5. Jim

    Mark Olson Guest

    What you are describing is by far the most common arrangement on inline
    four cylinder bikes. Vertical twins with a 360 degree crank also use it
    (e.g., my '81 CM400T). This style of ignition is known as 'wasted spark'
    because one of the spark plugs is firing on the exhaust stroke while
    its companion is firing on the compression stroke.

    Many autos also use this arrangement, my '93 Aerostar 4.0l V6 has it
    (no distributor).

    There is also a ignition scheme becoming popular on bikes and cars
    where the coil fits directly onto the plug, eliminating the plug wire.
    One engine like this is the Yamaha R1, among others.
     
    Mark Olson, Apr 26, 2004
    #5
  6. Widely used on cars for some years now. My '03 CBR600 also has this
    arrangment.

    SteveM
     
    Stephen Malbon, Apr 26, 2004
    #6
  7. Jim

    Jim Guest

    Interestng. I never knew. Anyway, the engine cuts out completely at
    5,000 rpm and pretty roughly back in at 4,500. After 5 seconds or so
    it smooths out and runs perfectly well until a downshift revs it back
    up. Anyone got suggestions as to a good source for parts on the
    Internet?

    Jim
     
    Jim, Apr 26, 2004
    #7
  8. Jim

    bret Guest

    1983 cb550sc runs great to 5000 rpm then cuts right out. It comes back
    Jim,

    I would approach it with the mindset that you have a bunch of little
    problems to look for, instead of one big one. My '81 cb650 was the
    same when I got it, it didn't want to rev past 5000rpm. I found all
    sorts of problems that I fixed and it runs perfectly now. Some things
    I fixed: bad spark plug caps, sticking mechanical advance unit, air
    gap on pickup coils was way out of spec, dirty carbs, corroded wiring
    connectors, rotten vaccum diaphragm on the petcock, timing off & carbs
    out of synch. I didn't have to buy anything to get it running right,
    just put lots of time into it.
     
    bret, Apr 27, 2004
    #8
  9. Jim

    Jim Guest

    Those are all good ideas. I especially like the airgap one. I'm gonna
    check that right away. The bike's been running fine. I recently
    cleaned the carbs, replaced the fuel filter and overhauled the vacuum
    shutoff in the petcock after lining the gastank. I was plagued with
    rust. So since that fix that stuff has all been working well. My
    thinking is that if it were a fuel problem a cylinder or two would die
    first, at least for a moment, before the others quit. That's what
    makes me question the ignition. And, if it were a plug or coil two
    would quit, not 4. But, if it were the spark unit that could kill all
    the cylinders at once. Maybe the pickup could kill them all too. I
    replaced the plugs. Didn't help. I didn't think it would but the bike
    needed new plugs anyway.

    Jim
     
    Jim, Apr 29, 2004
    #9
  10. Jim

    bret Guest

    1983 cb550sc runs great to 5000 rpm then cuts right out. It comes back
    I noticed a huge improvement after setting the air gap. You can loosen
    the screws on the pickup coils and move them closer to the rotor,
    using a feeler guage to get them to spec.
     
    bret, Apr 29, 2004
    #10
  11. Jim

    Jim Guest

    Haven't yet tried the airgap thing. Last night, in the dark, I taped
    on an ourboard sparkplug so I could observe the ignition as I ran it
    down the road, on 3 cylinders of course. Well, I always had spark. It
    never faultered. I think the ignition's working.

    I'm gonna be checking out the fuel system, filter first.
     
    Jim, Apr 30, 2004
    #11
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