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running like a dog under 7000rpm

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by syd rs125, Dec 25, 2007.

  1. my bike is a 2001 aprilia rs125 with 15000km on the clock and i know they don't have much drive before 7000rpm normally but it's lost a consideral amount of power and is running like crap at the moment.
    i have just put a new tank of fuel in and cleaned the power valve.
    I will change the spark plug today does anyone else have any ideas about what could be wrong ??
    I am not very mechanically minded but the bike has been ridden for the past 6 months without missing a beat and is always topped up with the best oil.
    Any help would be greatly appreciated!!

  2. If I was you I'd check
    1. the air filter
    2. as you've already mentioned, the spark plugs
    3. clean the carbs
  3. If the powervalve is stuck open then the bike will suffer untill powerband.
  4. ok excuse my ignorance but.

    1. air filter 1. Is that under the tank it looks like 2 plastic snorkels coming out of a box is that it??? and what do i check for do i just unscrew the box and clean the filter??

    3. Carbs. how do i clean them is it an easy operation?? do u know any sites on the internet that explains how to dismantle and clean with diagrams? or do i just run some sort of carb cleaner through the tank??
  5. Check powervalve motor too
  6. What causes the powervalve to stick open??
    I cleaned it about 2 weeks ago but then went on a ride to the putty and stopped at the half way house and re fueled is it bad fuel there??
  7. I read on an aprilia forum about the powervalve motor and that some rs125's have them under the pillion seat but some use a different powervalve without a motor is this correct?? and i have looked under my pillion seat and there is no motor or electronics that i can see.
    where else would i find this motor??
  8. It's probably under the tank but you would want to get hold of your bikes workshop manual and a look it up. It maybe avail as a doggy (pirated) download from the internet. I'd check the Aprilia forums as a first port of call.

    I'm not trying to belittle you but if don't know where the air filter is cleaning the carbs is going to be beyond your ability. Once again that'll be in the workshop manual.
  9. Try the aprillia forum here:


    The carb is easy to draIN - there is no reason I can think of to pull it all apart.

    Undo the large 14mm nut on the bottom of the float bowl. Let this drain into an icecream container lid or something similar so that you can see if there was any muck in there. The main jet is accessible once you remove the nut - you don't even need to pull the float bowl off, although it will "fall" off anyway once you remove the nut.

    I think the prob is more likely to be in the power valve area. Follow the cables to where the motor is that drives them. You should see the mechanism move as you rev the engine. There is a procedure for checking - the UK forum should be the best help.

    All the best

    Trevor G

    PS Just reread your thread title and it looks like the PV might be stuck open.
  10. Thanks alot guys i will pull the powervalve out and have a look tommorow. wife won't let me out of the house today but i will let u all know how it goes tommorow.
  11. quick question when i clean the blade part of the powervalve do i need to lubricate it before putting it back in??
  12. "do you have to change the powervalve gasket when u remove the powervalve to clean it or would it be ok to reuse it????"
    I just read that on the aprilia forum and the answer was "if its split or worn replace it."
    now when i cleaned my PV last time the blade was attached to a wire and the wire went into a black pastic cap and sleeve is that a PV "gasket"?? because when i was cleaning it last time black fluid was poring out of it could that be a "split PV gasket"???
  13. Last rs125 i looked at the airbox was under the seat. Undo the screws, clean with kero, wash with water, re oil, put back in.

    The power valve motor should be at the other end of the powervalve cable, that from memory is under the tank, near the battery. Give it a good spray with WD40.

    Gasket wise, u can either get some gasket paper and cut a new one, buy one (really no point), or if the old one is not broken, just smeer some threebond or something on it.

    The black carbon goo, is normal, u should see the rgv, it pours out of the powervalve cover. From previous knowledge, the powervalve connects to the black plug thing, and in the plug thing there is a spring and a washer. Make sure the cable connects to the valve.

    Smear some 2t oil on the pv before putting it back
  14. cheers natta really helpfull stuff i'll let you know how it goes tommorow.
  15. I have a PDF of the workshop manual

    It might be too big to email it

    PM me your email and I'll try.

    if your close to the eastern suburbs i can burn you a copy and drop it off

  16. At 15000km it might be coming up for a rebuild if it hasn't already done so.
  17. its due at 20,000 at the earliest it had the rings done at 14000 do the rest 20,000 mechanic said.
  18. Ok just changed the spark plug and took out the power valve and cleaned it went for a 20km ride and still same problem below 7000rpm it is spluttering different exhaust sound to normal sounds like i'm about to run out of petrol although tank is full and tap is on. extremely hard to get it off the line without the engine screaming around 8000rpm.
    looks like carbs and air filter next!
  19. here are some pics of the old spark plug hope they mean something to someone. hope these work

  20. Looks like the fouling from lack of fuel, but plenty of oil injecting, which indicates carb problem, as it is not delivering enough fuel to dilute the oil correctly...