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bike won't rev?

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by kyo3email, Mar 14, 2009.

  1. Today I was riding on the old road and I all of a sudden lost 80% of power.

    The bike all of a sudden didn't want to rev past 5000. I managed to get back to a shop in hornsby. It wasn't working properly, but as these things go as the mechanic took it around the block the bike ran fine. :roll:

    The shop was closing. So I didn't leave it with them.

    I was wondering if anyone could shed some light on this problem and how to fix it.
  2. Maybe water in fuel?
  3. a spark plug or lead failed
  4. Bike won't rev = twist throttle further :LOL:

    (Yes I know, useless post)
  5. A very vague description that may have 50 reasons.
    Suddenly is clue. Lost 80% power. Recovered power later.

    Not a broken engine component as recovered later.
    A bad electrical connection to coil. Check wiring. Ht wire loose on plug. Water in ignition system and /or wiring. Dried out by itself. Did you ride through water/storm?
    Blocked fuel filler cap breather (fuel starvation).
    Water in fuel that eventually got gobbled up by engine then motor cleared it's throat. Fuel line/fuel tap blocked by dirt, paint or rust flakes.
    I guess you are worried it may happen again. Give us more info like air temp, rain, did you wash your bike before riding, did you fill up from an old servo en route or your regular station. How many km on the bike?
    Did it run rough, cough or backfire?
  6. Thanks for the help thus far.

    To provide some more infomation. I'd been riding the bike fairly hard at the time, all the time it was running perfectly. I had slowed down as there was a car in front and then when I cracked the throttle open to over take. It didn't want to accelerate.
    -Temp was about 24degrees and I hadn't been riding in the rain and I store my bike in a garage.
    -Engine temp was normal.
    -I filled up from a Mobile servo I'd been to before and never had problems with the fuel, in the past.
    -I pulled over opened the fuel filler cap to check i still had fuel and had plenty left, i also switched it to reserve to see if that would help. It didn't.
    -Also when i pulled over i switched the engine off and on a couple time. It started no problems (no need for choke or throttle).
    -clutch out or in neutral the engine would rev up although in a bit slower than usual.
    -i rode the bike on limited power for about another 10-15km - to the closest bike shop (but they were closing at the time, nice of them to have a quick look at my bike). Engine temp during this time remained normal.
    -there is 18,000 km on the bike
    -I'd ridden over a hundred that day before it happened.

    Thanks R Moore again for your help. I am conerned this will happen again and fortunately it didn't die completely and within a reachable distance to help. I'm also glad it didn't happen mid corner.
  7. Sounds like you lost a cylinder or two.. Check coils/leads/plugs/fouling

  8. +1.

    Sounds identical symptoms to my 'lil zzr when i popped the left cyclinder... couldn't get it past 5 grand rpm... if you lucky its only a lead or spark plug... (i fooked it and got piston slap according to my mate who knows more about the internals then me).
  9. This tells us it's not the tank vent.
    this tells us it's not crap under a float needle. it wouldn't have started so easily. The fact that it didn't clear with revs also indicates this.

    It's not handling loaded conditions

    The guys above are likely right. Plug. Lead. Coil. CDI. In that order.

    Though the fact it got better is sus. May indicate the lead breaking down under temp.
  10. Thanks for the help guys!

    I hope it is not a cylinder issue. I'm not in the best financial position at the moment. Although losing a cyclinder would explain the nature of the power loss pretty well. Hopefully the lack of smoke, irregular noises and lack of over heating is a good sign. Fingers crossed.

    I tried to make the problem come back the next day and the bike worked normally.
    Although at one stage in the day it did struggle to start, which is typically unsual, which again made me think it could be the fuel...?

    Although just to make sure i'll take your suggestion guys and go over all the coils/leads and pugs this weekend.

    Thanks again! :)
  11. Prob not the best advice either ;) How do I know? Murphys Law. :LOL: Pull the throttle during a non revving period and it'll be that moment that the bike's non revving problems will disappear - as what happened to me on the wknd whilst riding in the wet with suspected water in tank.
  12. Fuel filter partially blocked? Enough flow to start but not to pull under load?
  13. + 1 on fuel filter.. a common thing to be missed out on maintenance especially with a bike more commonly ridden by learners and RE.

    not the same but my car was doing EXACTLY what ur bike is doing isolated the problem to be fuel filter

    pretty funny actually it was the original fuel filter the car was made with..... my car is 20 years old :D the amount of gunk in it was UN belivable
  14. i had a prob like this, cept my old man was on it when it happened.

    we had dodgy fuel that time, but got carbs cleaned as well.
  15. personally it sounds like fuel issues to me as well. A supply issue.

    Could be a ignition issue (ie, spark getting blown out because it's too weak) but that tends to "Stutter" not cut out completely, in my experience, which may be limited :p
  16. If its running OK, stop it, take off one plug lead and start it again, then try and ride it (in a safe area). Thats what its like running on one cylinder. If thats how it was running on the problem day, its likely an electrical issue on one coil, HT lead, plug etc.
    If thats not what the original problem felt like, its more likely lack of fuel flow due to blocked filter or similar as others have said. Good luck!
  17. what did it sound like when u were reving it ?

    was it running rough or just didnt want to rev past 5k?
    generally if your lost a cyl the bike will run rough, shake fairly violently and sound like a 1980's dirty bike gone bad