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Aprilia RS125 keeps stalling after stopping and taking off!

Discussion in 'Technical and Troubleshooting Torque' started by apriliars12502, Aug 17, 2012.

  1. Hi guys. I just purchased a 2002 aprilia rs125 second hand with around 20000kms on it. not sure if its been rebuilt or not. it has no problems when i take off after i start the engine but when i come to a stop after shifting down to first gear from whatever gear i was in and then try to take off on first gear it starts moving and then just stalls. and after that i have to keep trying many times to get it moving properly again. im even finding it difficult to find neutral. my friend said that it may be because im not in first gear yet but the same issue happened a couple of times even after i went down from neutral. i usually rev up to 3500 or so rpm before letting go of the clutch and this usually works for me from start off. i also noticed a couple of drops of oil from my exhaust. is that normal? my friend said it is normal and it may be just the 2 stroke oil but im slightly worried. any help would be appreciated guys. im new to motorbikes but im willing to learn about fixing them and im happy to spend my time maintaining it.

  2. Welcome to the club fellow ape rider!

    Only time I had an issue like that is when I started riding my bike and had forgotten to take the choke off. I was riding around with it on once, and every time I went into first, the engine would stall on me. Once I took the choke off, no more issues.

    Also, are you warming up your engine properly before riding. Wait till at least 3 bars, then ride one or two km's gently, then feel free to let her out!

    Also, on a hill, you'll have to rev way past 3500 to get her going, or it'll just bog down on you and probably stall. Feel free rev her up to 5 or 6000+ on hills, then let the clutch out.

    Don't worry, you're not going to hurt it!

    The oil form the exhaust is completely normal. Mine does the same. You'll notice where you park, there really isn't much oil that actually gets on the ground. Just keep your eye on the oil levels and keep her topped up with the best 2T oil. I use Motul _________ with the Fd rating which is essentially the best. You could get away with Fc, but nothing less.

    Neutral is a biatch to find. The easiest way to find it is shift up to 2nd, then tap gently down almost giving it a half push, and you'll usually get into neutral. I can hardly ever get into neutral from first and shifting up.
  3. Thanks a lot for the quick reply! The choke has always been off when I start riding. Also how long do I need to warm it up for? With the choke on, on a cold morning , it only idlers at around 1500rpm and I usually warm it up for 7-8 minutes. And occasionally it would just turn off even when the choke lever is down. Do I need to increase the idling speed? Also, on average how much would a top end rebuild cost? I'm happy to spend the time to learn and do it myself but I have no knowledge of motorbikes at all. I have also noticed that the clutch lever is a bit tight, but I haven't ridden many bikes and I'm just comparing with the c.br125 I had before for two weeks.
  4. Does the '02 have a temperature gauge on the instrument panel? Once you hit 3 bars, which would take about 7-8 minutes on a winter day in SYD, you are probably good to go, just take it easy for the first couple of KM's.

    Do you mean it would turn off while you're warming it up, or after you have started riding and are idling? My bike will also cut out while warming up, but that's normal.

    Once you start riding though, it shouldn't cut out.

    What do you mean by increase the idle speed? If you're idling, don't you have zero speed because you're just sitting there?

    Depending on who you go to to get the top end done, it could cost anywhere between $500 to $1000. I'm not exactly sure as I haven't had to do one on my bike yet, but when shopping around, I called a an Aprilia dealership to find out, just so I can factor it into the price of my purchase.

    With the amount of KM's on your bike, it definitely looks like it's time for a top end if it hasn't been done before. Top ends should be done between 12 to 15 000 KM's and bottom end's around 30 000 KM's.

    The top end can be done if you're mechanically inclined, but I'm not, so I have no idea what to do and I don't even want to try.

    Go check out the Aprilia forum or 125ccsportsbike forums for more info. AND ask BoingK or Crashdummy on here, I think they've both done full rebuilds on this bike & would be more knowledgeable. Use the search function and you'll be able to find it. Great close up pics of all the parts which will probable scare you away from doing it on your own. It did for me!

    Let me know if you need the owner's manual or repair manual for your bike. I sourced them on the net and can just email them over to you.

  5. Mate - I just read this again...

    Definitely try revving much higher and see if you still stall. I think it just bogs down on you right at friction point, you let go of the clutch, and BAM, you've stalled! Happened to me all the time for the first week on hills till I got the hang of it, and I would sometimes rev it to 9 or 10 000, just so I wouldn't stall. After a week or two, you'll have mastered it, and will only have to rev to about 5000. you need to rev it high anyways if you want any sort of power off the line. Being only a 125cc, the thing is going to take off like a turtle anyways.

    Drops of oil is normal. It just like sweat down there. If it seems unusually excessive, you may want to check the oil seals.
  6. The oil leak is not excessive at all. just a couple of drops which im pretty sure is normal.

    Also it seems to stall when i come to a stop and then take off at a set of lights or roundabout. basically what happens is i usually try to get into first gear before i stop but i double check which gear im in and then when taking off i take off as usual but the bike starts moving forward and then loses power and stalls no matter how hard i rev it. but i realised that after coming to a stop if i change it to neutral and then go down to first gear by rolling back and forth whilst holding the clutch in and downshifting, the bike takes off fine. Do i have to do this every time I take off? So to sum up, it doesnt stall when idling. Only when trying to take off after stopping by downshifting. I am having no issues taking off normally. It is only when I am in a higher gear but then have to downshift to take off.

    Also about the rebuild, I will have a look into it. Any idea how to tell if the bike needs a rebuild because other than this issue the bike seems to run fine but then again I have no experience with motorbikes so what would i know
  7. Have you adjusted the clutch lever free-play ? Owner's manual details how to do it.
  8. I thought about that but would it be the reason because the clutch lever is fine when i take off normally and change gear.
  9. Clutch drag was making it nearly impossible for me to find neutral, just like you described.
  10. okay i will definately try that! should i adjust it so that there is more free play or less? thanks!
  11. Other thing is, are you changing down through the gears, letting the clutch out, letting engine braking slow you down? Or are you coasting in with the clutch in, letting the brakes do all the work? Perhaps if it's the latter you're... I dunno, ending up with too rich a mixture/too much oil (are the Aprilias pre-mix two-strokes or do you have a two-stroke oil reservoir?) Sounds to me like too much fuel/oil in the cylinders...
  12. Finally figured out what was wrong. I am just a noob and was letting go off the clutch as soon as it began moving! Thanks all for the help!
  13. You really have to ease it off the line with these babies.

    Side note; Please dont compression brake an oil injected two stroke.
  14. Isn't it more "You end up easing it off the line because it's kinda hard to get a good race launch right"?

    Also OP, lol, just lol. :p Lucky me I learnt to rev to ~6000rpm when I test rode mine, after I stalled out the front of the dealership maybe four times in a row because the rpm was way too low (I thought the bike was broken... hmmph) and they came running up to me yelling at me telling me what to do. Since then I haven't stalled.
    3500rpm is too low IMO. You can do it but I'd be on that clutch like a mofo and as soon as you start moving start ringing the tits off it (still with clutch) to get it in the powerband.
  15. Please explain. It was me who suggested it, and if I was wrong I want to not suggest it again! Always used to do it on my RDs and RZs back in the day... what's the issue?
  16. Lack of engine lubiness from not having the throttle open. And 2-strokes don't really engine brake as is? And OP, chuck a capful of oil in your fuel when you fuel up!
  17. Since the engine internals are lubricated by the fuel/oil mixture, which only comes through if the throttle is opened (letting in the mixture). If the throttle isn't open but the engine is still turning over rapidly due to engine braking there can be insufficient lubrication of the internal parts.

    Pretty sure they fixed that on some of the supersport 500's and stuff, someone might chime in, but yeah that's what I heard.

    From Wiki:
    "All two-stroke engines running on a petrol/oil mix will suffer oil starvation if forced to rotate at speed with the throttle closed, e.g. motorcycles descending long hills and perhaps when decelerating gradually from high speed by changing down through the gears. Two-stroke cars (such as those that were popular in Eastern Europe in mid-20th century) were in particular danger and were usually fitted with freewheel mechanisms in the powertrain, allowing the engine to idle when the throttle was closed, requiring the use of the brakes in all slowing situations."

    Also could someone quickly explain to me something two-strokes and constant throttle position being bad for them? My Dad mentioned it one day and I forgot to get him to explain it to me. Something about hot-spots and holes in pistons or something?


  18. I had to keep the revs sitting at 3500rpm and balance the clutch slippage to get a good take off, if you just hold it and then dump the clutch you will stall.

    Are there any other mods done to the bike? Have you checked to see if it still has an airbox or replaced to a pod filter?

    Change the gear box oil as well, they do get tempermental and don't like to find neutral sometimes.
  19. I am yet to refill the oil and fuel of the bike. Is normal unleaded fuel okay or do I need to go for premium? and what do you mean I need to add oil when I fuel up? also how do I know when to fill the 2 stroke oil?
  20. Everyone will say something different about what fuel to use. I say... 95 or 98, but I'm not sure what the older models run well on.

    Regarding oil: does yours have a separate oil tank or do you have to mix it yourself (again not too sure with the older ones and I've heard some people disable having separate oil)? If it's separate then essentially as long as there's always "some" oil in there it should be fine, and expect ~5 tanks of fuel to 1 tank of oil. If it's not separate; do your research and haaaave fun! :p

    The capful of oil in with the fuel is a "tips and tricks" type suggestion. Not a written rule but helps protect from seizing and helps keep the engine wear a bit more even.