Welcome to Netrider ... Connecting Riders!

Interested in talking motorbikes with a terrific community of riders?
Signup (it's quick and free) to join the discussions and access the full suite of tools and information that Netrider has to offer.

Loss of engine power

Discussion in 'Technical and Troubleshooting Torque' started by Milpool, Apr 16, 2016.

  1. Today after about an hour and half of riding country roads I ended coming back closer to home and was at a traffic light. I took off fine but not long after shifting into third hitting around 60km/h my the bike jolted forward a bit two or three times; each time the tacho needle dropped instantly done to around 0 then back up again. About 2 minutes later I cut the throttle and it did it again once. Yet the rest of the ride home was absolutely fine including some highway driving. Does anyone know what would cause this and is this something that could happen again?

    The only thing I could think of with my very limited knowledge was something wrong with the ignition so I checked the battery and it's reading 12.8v so that at least should be fine.

    • Winner Winner x 1
  2. possibly a fuel blockage - you may have blown the crap out. if that's the case make sure you fill up at popular servos.

    there could be a mechanical reason also like clutch slippage maybe but if your electricals are ok then I'd guess fuel is the issue.

    disclaimer - when it comes to anything mechanical or technical I am an idiot and you would be well advised to be very cautious about following any advice or recommendations made by me (probably should make that part of my signature).
    • Funny Funny x 2
  3. Last time I filled up was at a BP and put in 95 octane (normally I don't bother but the 91 had ethanol). I hope it is just a temporary blockage.
  4. if the revs didn't suddenly drop, but the tach needle did, sounds like intermittent electrical.
    specifically, power to coils or ignition module.. or everything...
    • Informative Informative x 1
  5. Great... how difficult is it to replace a CDI?

    Also for what it's worth, I just remembered that about a minute or so after filling the bike last time I had to do a u-turn and half way through the engine cut out. I pulled over and everything seemed to be working fine so I rode off. And it has been fine until this issue.
  6. could be wiring and plugs to the ignition switch then..
    you'll have to investigate and find the problem, or take it to mechanic/bike auto elec
    • Like Like x 1
    • Informative Informative x 1
  7. A battery showing good charge doesn't mean that there still isn't an electrical issue. I assume you thought that as there was nothing else mentioned to indicate the electricals were OK.

    It is irrelevant if it is working fine. You haven't established what is wrong yet. Unfortunately that can be difficult with an intermittent fault.
    You are going to have to do a bit more sleuthing to determine what is going on.
    • Like Like x 1
  8. I was just following on from the OPs comment in the first post saying that he had checked the electricals and they seemed fine. refer also to my first post in this thread for my disclaimer :D
  9. I wasn't trying to put you down. I just trying to educate in case you had misunderstood the concept, particularly as you said your mechanical knowledge wasn't great. He said the battery was OK not that the electricals were. I was trying to clear up a misunderstanding should there be one.
    • Like Like x 1
  10. all good, just funning, no need to take it or me so seriously :)
    • Like Like x 1
  11. #11 Milpool, Apr 17, 2016
    Last edited: Apr 17, 2016
    Right, so a bit of an update. I have now checked the fuel filter and it looks spotless, which is annoying because considering this all started right after I filled up last time I was thinking it was just garbage in the fuel tank or something.

    I also had a quick look at the pin connectors to the CDI and they looked spotless as well. I know that's hardly a thorough look at the electronics but I really don't know what I'm doing there. Also for what it's worth spark plugs were done a week before I bought it (I have the receipt) so I also know it's not them.
  12. The tacho derives its timing directly from the ignition Low Tension side of the ignition coils. Dropping to zero and the associated loss of power points to an intermittent electrical as others have said. Start with the basics and work your way up.
    1. Battery connections, are they clean and tight.
    2. Is the negative from the battery bonded to the frame of the bike tightly and securely.
    3. When this happened did you lose headlights, electrical lights etc on the instrument cluster?
      1. If so then it is a wide spread power failure and you should look at switchgear such as Ignition switch and Kill switch.
      2. If no then the problem if further upstream and could be dirty connectors etc.
    4. You said the issue happened in a tight U turn?? Shorts to frame on the wiring that runs up through the steering column is a possibility, check that there is no wear on the wiring or over tension in the plugs when the steering is hard over.

    • Agree Agree x 1
    • Informative Informative x 1
  13. Awesome, thank you so much. I'll check that stuff out later when I get the chance. Also I didn't notice if I lost any other electronics on the bike, it was pretty bright out at the time and the indicator wasn't on.
    • Informative Informative x 1
  14. It could be a loose kick stand not closing the switch fully or loosing connection when you go over bumps. The engine runs through the kick stand switch on the gpx250. Just a thought.
    • Like Like x 3
  15. That's a good point peter079. I'll have a look at that tomorrow. The problem stopped for a couple of days then happened again tonight. It was a well-lit area so I didn't notice if the headlights went out but all the dash lights were fine.

    On the subject of electrical issues, I read in the manual that the oil light will be lit up when the engine is off and then go away once the engine has started, most of the time though the oil light is just off. Sometimes it comes on when I turn the key but before I start the engine It's not a huge deal to me as I know there is no oil leak and the light hasn't come on when the engine is running. I don't know if that's a related electrical fault or not though.
  16. The oil light will be on before you start the bike because the oil pressure switch doesn't see any oil pressure in the galleries. Once you start the bike the oil pump pressurizes the galleries and the oil pressure switch is happy.

    With my first car I could watch the oil light go on and off as it was cranking due to the pump moving just enough oil to make the switch happy for a half second at a time then it would go dim again.
  17. But the oil light is usually off regardless of whether the engine is on or off. That's what I found odd.
  18. oil pressure switch may be stuffed... or the ground wire from engine to frame to battery is busted
  19. Either way get it checked and fixed. You need to know if oil pressure drops. The time spent with the engine running without oil pressure tends to be expensive. If it happens on the move and the motor seizes the result could be fatal. to you as well as the motor.
    • Like Like x 1
    • Agree Agree x 1
  20. Okay, I'll have a look at the ground wire tomorrow. If that doesn't fix it I'll take it in. Can anyone recommend a good place to take it in Brisbane?