2010 Yzf-r125 Power Loss Please Help

Discussion in 'YZF R125 General Discussions' started by Luke Saunders, Feb 9, 2017.

  1. Hi guys,

    So the story is: I was riding home from work yesterday and as I was overtaking somebody my bike suddenly lost power. It lost power for about two seconds and then regained it and kept going. I thought it was just a error in the engine or something so I kept going and about 20 seconds later the bike lost all power again, this time unable to regain it.

    I naturally pulled in the clutch and eased it to the side of the road where it stopped. I had a look around the bike to make sure it wasn't my chain (sounds silly i know but ive had a history of chain issues). After having a look around and finding no problems I tried to start the bike again.

    The ignition was fine to sounds of it losing battery or anything, but it never turned over and the bike wouldn't start.
    I had to get it towed back to my house and I have no idea why the bike will not start anymore.

    Is this a spark plug issue??

    Its worth noting as well that I do an excessive amount of miles throughout the week. I do about 1056 miles per month. Is this bad for a 125 to do? Is it too much work for it?

    Thanks guys all replied greatly appreciated!!

    - Luke

  2. This happened to my Wr 125 and when I went and it got checked my piston had smashed inside of my engine when you say loss of power did your whole bike just conk out was there still your dash lights on but the bike wouldn't start I would get a snake camera down your spark plug and check ur barrel and piston

  3. The dash lights stayed on, it just literally lost all of its power but the engine did NOT turn off at that time, it only turned off when I stopped and turned the engine off myself, thanks

  4. Roughly about the same as me then i've just clocked over 32k in 4 years :/
    Mine kept dying on me last year,
    check the basics first, make sure it has oil. Check the HT lead is secure mine became loose.
    Make sure the kill switch isn't rocking (flick it on the back off)
    mine ended up at the garage for a loose coil

  5. Okay thanks for the advice mate, I've only done 13k miles, but i've done about half of that in the last year and a bit. I'll check everything when I get home from work and update the post.
  6. RPS

    RPS Member

    Good advice to check or replace plug, ht lead and oil. Have you done a service in last year which you should have done for mileage your doing and it will be coming up to a second one. Oil and filter change would be beneficial at much more frequent intervals than this eg every 1800mls if you are not already doing it. I fall ok bike should bump start easily.

  7. Thanks for the advice, I'll check or replace all of those things asap...

    I just got home having had it on charge overnight; the ignition works but the bike will not start (turn over). I'm going to assume its definitely a spark plug/ ignition problem.
    - To be honest I haven't paid any EXTRA care to the bike since doing my high milage, you're entirely right i should definitely be topping things up/ servicing the bike more.
    I've ordered a new spark plug, we'll see if that fixes the problem. I'll keep you all posted.
  8. RPS

    RPS Member

    Faulty plug or ht lead shouldnt stop engine turning over. Make sure handlebar kill switch is in right position and bike is definately in neutral If all ok i would be wanting to make sure engine is ok.
  9. Blazer

    Blazer Member

    Is the starter motor turning the engine over?.

  10. I apologise guys, I had the wrong idea about what turning over meant; yes it does turn over, but it does not start!

    So bit of an update, I bought a new spark plug today from halfords and fitted it; it was not the problem. Bike still does not start.
    I'm a little worried now that it could be a big issue...
    I've had people tell me it could be the battery, but surely if the battery was dead, then it would not turn over? (it does)

    Any suggestions at this point would really help guys!


    - L
  11. RPS

    RPS Member

    After turning over the engine, remove the spark plug and smell whether petrol has got through to engine which would indicate its not firing by igntiion system despite new spark plug. Therefore look at ht system. If no petrol smelt; then is fuel pump working? When you turn ignition can you hear fuel pump priming for a second or so.
    Blazer likes this.
  12. Blazer

    Blazer Member

    If it seems like it could be an electrical fault, then there are a few known problem areas. First and easiest to check is the sparkplug cap, unscrew it from the ht lead and check inside, the original screw thread has been known to snap off. Second thing to check are the wires at the bottom of the ignition barrel, wires have sometimes been known to snap off when pulled tight during cornering. Third thing you could check is the coil, it is tucked away under the tank so can be neglected and become loose or the connections can become corroded.
  13. Blazer

    Blazer Member

    Forget my previous post, if you think its an electrical problem then the first thing you could do to confirm, is to remove the sparkplug re-connect the ht lead then rest the plug against the engine so it has a good earth, then turn the engine over. If the plug sparks then all is OK and it will most likely be a fuel problem like RPS said. If the plug doesn't spark then you can try tracking down the problem by following my previous post. Hope you get it sorted.
    Last edited: Feb 11, 2017

  14. the battery could be at fault
    even though it seems to be working if it doesnt have enough power left in it, it will not start the bike, If you have got one, just put a milti-meter accross the battery, and see what voltage is is giving out. (Should be about 12.46V)
  15. RPS

    RPS Member

    Lots of good ideas to work through and let us know what you find. If battery suspected, as long as it is not completely flat, you should be able to bump start it. Mine will bump start easily in 2nd at walking pace.

  16. Best bet to check if it's a battery problem is try and bump start the bike when my piston smashed I could hear a loud grinding noise when trying to bump start and in case it is the worse case scenario I wouldn't constantly try and start it up I had this exact problem all the electrics work bike turns over but doesn't start trust me when I say take your spark plug out and get a wire came down it and check your barrel and piston make sure your barrel isn't scraped and piston is still intact

  17. Alright so bit of an update: I bought and fitted a new spark (not the problem), I have taken the entire bike apart now, I have checked the air filter, ht leads, fuses, battery, and oil, and none of these things seem to be causing any problems. Getting very worried I may have to arrange a funeral and proper burial... : (

    I attempted to bump start the bike, and so I put it in second and got my dad to push me... the engine will not even start this way... as soon as I release the clutch the engine rotates, but it does not start.

    I think I'm going to have to take the bike to a mechanic, truly no idea whats going on.
    In response to Greezy, I do not own a wire cam, this is why i'll probably need to take it to a mechanic because can't touch or get to internal engine parts, and also I do not hear a grinding noise of any sort... its as if the bike is fully functional, but simply does not work : ' (

    Thanks for the help so far guys, I'll get it looked at over the next few days and post an update.

    - L

  18. Do you guys think it could be an issue regarding fuel? Fuel delivery? Hmmm

  19. Do you hear the pump prime when you turn it on?
    Don't suppose you've had wet weather?
  20. Blazer

    Blazer Member

    As @Sacko-r125 and @RPS say, if the you can't hear the fuel pump buzzing when you turn the ignition on, then it will be a fuel problem. Have you tried removing the spark plug to see if it sparks, it should spark when it's connected to the HT lead and earthed against the engine while the ignition button is pressed?. If it does spark then you can rule out an electrical issue and it will be either a fuel or mechanicle problem.

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