Ad Widget



No announcement yet.

High-end hesitation/miss:

  • Filter
  • Time
  • Show
Clear All
new posts

  • High-end hesitation/miss:

    Lately I've been noticing an issue. While cruising on the highway (75-80 mph) and I go to pass someone and twist the throttle, there is a 1-2 second hesitation/bog before she starts to pick up and accelerate. As an experiment yesterday, I waited for an open stretch of road, did the same thing but didn't let off. It felt as though there was a miss or stumble as she kept accelerating (similar to the feel when switching from 'normal' to 'reserve' when the tank gets low and the fuel takes a couple seconds to switch over).

    I don't notice any issues at low speeds through gears 1-4. Only at higher speeds. I'm leaning more toward a fuel issue than a spark issue. I took a look at the manual to see about a fuel filter and it appears there is just some sort of screen in the fuel petcock. Is this a common area to look at?

    I plan on dumping some Techron or Seafoam into the tank and seeing what happens as well as possibly cleaning out that petcock. Are there any things I should be leary of when taking off the petcock? The manual warns of an O-ring to watch for...anything else? Or, any other places that I should check?


  • #2
    A "stumble" on acceleration at high speeds only could be caused by a few issues, in the order I would check to resolve would be...
    1. Non OEM air filters allowing too much air flow at high speeds.
    2. Vacuum leak(s)
    3. Dirty carbs
    4. Worn carb parts (needle/air jet)
    5. Reduced fuel flow due to a dirty or clogged system, or a faulty petock.
    If your issue is dirty carbs or clogged fuel system, the seafoam might possibly help things, depending on what is clogging it. Seafoam will not make rust or dirt particles go away for example.

    93 750 Kat

    Modified Swingarm, 5.5 GSXR Rear with 180/55 and 520 Chain, 750 to 600 Tail conversion, more to come. Long Term Project build thread

    "I've done this a thousand times before. What could possibly go wron.... Ooops!"


    • #3
      clean the carbs


      • #4
        I recently had an issue like this on mine bike (pre 600). It would miss when up around 9-10.5k when wide open. I then noticed my filters (k&n pods) were very dirty. Cleaned and re-oiled the filters and all is good again. Maybe clean your air filter and see it that helps...


        • #5
          Follow up:

          I tore in to the air box a couple weeks ago to clean the air filter and do a visual of the carbs. I cleaned the air filter and, while everything was out, fired her up and sprayed some carb/choke cleaner through all 4 carbs. When I was done, I noticed a residual puddle of stuff toward the back of the air box. Upon further inspection, I noticed the drain tube was kinked about 1/3 of the way down. I straightened it out and everything drained out of the air box (quite the mixture of stuff).

          I put everything back together and she runs great (no miss, no hesitation, no high speed stumble, etc.)! Still going to run some Techron through on the next fill up.

          I suspect this: due to the drain tube being kinked, whatever fluid that is supposed to drain got backed up and settled in the airbox. Upon hard acceleration in low gears, this really didn't seem to affect anything and I think that is due to the g-force of acceleration keeping that fluid pushed against the back of the box while the air was being sucked in. However, at highway cruising speeds, when the throttle was cracked, I don't believe there was sufficient g-force to keep the fluid out of the way and the resulting air turbulence within the box stirred it up and allowed some to get sucked in through the carbs. That could possibly explain the symptoms I was explaining.

          Anywho....things seem to be back to working quite well now.

          And also, thanks to everyone in regard to the turn signal relay. I bought one from Autozone last night for $5 and with some minor electrical work (ie. cutting off the old plug and splicing some 1/4 connectors to the wires), I hooked it up and everything works fine. It actually fit inside the rubber casing used to hang it from the battery tray and the prongs cleared the other box back it is in the stock location with no issues.