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ZZR250 intermittent power lose, **resolved**

Discussion in 'Technical and Troubleshooting Torque' started by brownyy, Jun 30, 2009.

  1. Hey all;

    My bike is a '97 ZZR250, (inline two) with an '07 engine in it. So the bike is 12 years old, the engine 3.

    Some time ago I noticed some strange power issues. While on the highway at 100km/h I would open the throttle to pass and virtually nothing would happen. It would gain a 1-2km/h every few minutes, i.e. huge power issue. While the ZZR250 isn't a power hungry beast, I used to be able to open it up at 100 and still have acceleration to 140 without a problem. Fact is, it loses power.

    However, with the throttle fully open or at the position I would have it for that speed, the bike does not slow down (i.e. not a 100 % lose of power). If I backed the throttle off more until I hit 90km/h (or any arbitrarily speed slower) then opened up, it would not accelerate. And between that throttle position and fully open is like one huge long flat spot of absolutely no action.

    I thoughts at first were something carby related, fuel or air delivery. However the air filter was recent replaced, yet I haven't inspected the fuel tap internals (is that even possible to open them up?) or pulled apart the carbs. Side note, the carbs are the original ones, not replaced with motor.

    However it appears to do it more often when there is water on the road thus creating white spray behind the cars. This had me thinking it was electrical, not sparking on one cylinder. However, when I killed my first motor, I killed one cylinder, the power lose in that was massive, wouldn't rev past 5k-rpm under load, and would hardly make it to redline in under 5 seconds.

    One thing I tried a few times was clutch in, let it return to idle for a few moments, then power up and continue on. Sometimes this helped, today it didn't.

    When it was starting to really shit me today on the way home, I pulled over and played with the revs. Grabbing a fist full it took time to wind up with several noticeable flat spots on the way up to redline. So now i'm thinking electrical of some nature again.

    Does anyone have any other ideas of what it could be or which cause it is likely to be??

    Thanks for your help.
  2. Figuring its a 2 cyclinder i didnt think it had much power up the top end of speed. head wind?

    Yep if a piston wasnt firing on a 2 cylinder you'll know it. i really notice it on my 4 cylinder car.

    Have you done anything to the exhaust? where did you source teh engine from??

    i noticed when i put the stock exhaust on my bike it ran liek dogs balls, no power at all, when i put my straight pipe back on it had so much better response to the throttle. has the new engine been tuned to the bike?
  3. The new motor went in last october, and has done just short of 30,000km's since... same pipes (stock) for both old motor and current... :(
  4. Did you change the coils & electrical system over with the new engine?
  5. ive heard of ECU hookup the wrong way so spark 1 was hooked up to spark 2
  6. Spark plug leads maybe? I only say this because I had a 6 cylinder Falcon that from time to time would lose power under acceleration. Didn't really slow down, but wouldn't accelerate either and spluttered a bit and then would start to take off again.
    Dad was a mechanic and started the car up in a dark garage and revved it a bit. Looked pretty impressive seeing all these sparks jump from 1 lead to another. New set of leads and problem fixed!
    Wouldn't hurt to try the bike in darkness with lights off and see if you get a similar effect.

  7. Try pulling over and switching it off for a couple of minutes, then starting it and trying again. Don't wait too long after starting to try the problem. This will tell if it is a fuel delivery problem.
  8. I dont think its a fuel problems hes cruising at 100km/h fine, its just accerlating past 100km/h to overtake i asume?

    what gear are you in and what revs when you are cruising at 100km/h
  9. MV; original electrics, same coils, same leads, the lot. Just swapped the motor itself, same carbs, wiring looms etc...

    Whitey; I'm thinking it's loosing spark somewhere like you said when it gets wet. This morning the bike was dry when I left, and was strong all the way to 160 (private closed road of course).

    t_mike; cheers for that idea, next time it happens I will try that one.

    Whilzah; 100km/h in 6th = 8k rpm. However same problem in 5th when it happens which is 9k rpm. It just doesn't want to accelerate at all when it occurs. When it's been fine, 4th, 5th, 6th, it still accelerates away from 100 solidly up to 140 before it starts slowing down.

    Saturday Arvo I've put some time aside to go over all the electrics with a fine tooth comb and look for any shorts or flash marks. Also been told to check the tank breather tube / vent. Looks like i'll be buying a lot of duct tape...

    see how goes.
  10. I'd say you've got a coil/lead/spark plug breaking down under load, (or a bad earth?)

    Good luck with, let us know how go.
  11. When it's playing up, does it feel like it's surging a little bit? My VTR250 has troubles cruising along at certain revs/gears. If I try and do 80 - 100kph in either 5th or 4th it'll surge/struggle. In my case it's highly likely it's a fuel problem - float sticking.

    I also know the sitting on side of rd and giving it revs and the flat spots you speak of, as mine does same.

    Don't rule out fuel probs yet.
  12. It is probably related to water. Wet air cleaner element.
  13. bit late and not sure if it helps but my gpx used to get a bit rough in downpours at times.. i kind of figured out that the issue was to do with water build up around the coils. maybe they have a weak seal to the rain ?.
  14. Update.

    Finally got some time to pull apart the bike. Once the fairings and tank were off, I quickly noticed a rub mark between the cylinder head and the RHS spark lead. So far it looks as if that's the only rub mark / short / flash marking between all wiring but i'll attack absolutly everything that I can with duct tape. Will check the air filter but I won't know either way if this is 100% fixed until the next decent downpour I'm caught in.

    Until then it's been running fine in the dry...

    Cheers all for your help, I'll update once it rains during a commute.
  15. Bike got soggy enough on the way home, sat behind a decent amount of cars kicking up spray... All good, no power loss. Yay for shit loads of duct tape.

    Thanks all.