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Discussion in 'Technical and Troubleshooting Torque' started by annoyin, Feb 2, 2005.

  1. HeLP!!!
    i was riding today and somehow while riding i felt loss of power, this was probably cause of my fuel running empty so i turned it to reserve. after turning to reserve my bike still felt weak.i came to a stop at a red light and the bike felt like it was gonna turn off but could still go but with a weak power. so i pullled into a servo and stop the bike and to refill up. when i noticed fuel leaked out. it stop leaking a short while after. i started up my bike again with a little bit more fuel and try to ride home. the bike now sounds funny, sounds like clodged up fuel or something?....and when i rev it it lags like it has no fuel, but then wenn the rev reaches above 10rpm its sounds normal and runs normal..
    can anyone help me with this problem???????????????????
    i ride a honda cbr 250 rr

  2. firstly find the leek and fix it ..
    because if fuels coming out , not only a fire risk , but that means it can suck air back in causing to to run like that .

    if your tank was low at the time , you might have a blockage somewhere (picked up some crap from the bottom of the tank)
    if its solid (matter) clean your carbys and fuel lines.

    if its water , add some metho to your fuel , in a car its 1 ltire to 50 l tank , so you will have to work out how much to put it , it will burn with the fuel and evaporate any water.
  3. does the CBR have a prime on the fuel switch if so thats the likely cause of the leak :) being left on prime is not good
  4. IIRC your bike uses a diaphragm carby, and the symptoms you describe are pretty close to what happens when you get a hole in the diaphragm.

    I'm hoping the fuel leak was just overflow. Where did it leak from?

  5. You may have got a bit of dirt under the float needle when you run to reserve.

    This leaves the float open and floods the engine.

    At higher revs it might be getting the right amount of fuel and thus runs fine.

    As someone else mentioned, find the leek.

    If it is around the carbie then remove the float bowl and clean off the needle with some petrol. Make sure you don't loose it as it is very small.

    It should just fall out when you remove the floats.

    Other then that I would be looking at air being sucked in through a reserve line, as someone hinted.

    although I had a similar problem when a had a plastic bag partially blocking the air intake.

    Good luck
  6. just to add to shabby's and groberts's comments..

    fuel leaking and funny sounding engine sounds like you may have accidently switched the fuel tap on prime-- fuel coul dhave flown
    throught your carby's, engine block and then into your exhaust ?
    this is going out on a lim i know, but it might be a possible cause
    (but there again.. if fuel went into the motor, you would have
    hydrolic lock up ????). i don't know. phuck nose.

    is it a 1 or 2 cylinder bike ?. 1 or 2 carby's ?

    often if you run you're bike out of fuel (particularly if it's a few years
    old), the carby's and tank can dislodge deposited crap.

    one trick you could probably do, is to empty the carby reservoirs
    and inspect their contents for muck etc ? (either by removing
    a drain plug, or unscrewing and removing them).

    if it is due to muck, replace/clean fuel filter. give the tank, tap
    and lines a good flush... and then give the bike a good floggin !

    try that ;)
  7. thanks for the reply people!...........imma gonna go try to find the leak. even though im new to pullin g apart bikes n stuff im gonna try to fix the problem!
    steps to how i can clean the carbys would be nice?
  8. the honda cbr is a 4 cyclinder with i think 4 carby's!
    im a newbie.....
  9. if you want to learn a bit more about the bike anyway, pulling the carbs out and cleaning them made my bike run a bit smoother (buy some carb cleaner first)
  10. thanks
    one other thing
    its pretty wierd now, the bike use to sound cold everytime, like even at normal temp. the lights blinks and its yellowish color u can even hear it in the muffler.now the lights are brighter and it doesnt blink!......smoother but when u rev tats where the problem occurs.
  11. Check your battery - at rest voltage. Poor battery charge can manifest at low revs where alternator delivery is at its lowest.
  12. hey
    where are the carby's?
    under the tank, under the air filter?
  13. You will probably have to remove your fairing side panels and you tank to get to them.

    I do advise against removing them and pulling them apart. If you do that you will have to balance them and this requires a particular tool, which is not cheap.

    I think you should find the leak and if it is one of the carbies overfilling then remove the bowl from that carbie. Put an old towl on top of the gearbox, so that if you drop the needle you wont loose it.

    Remember I am only guessing the problem is on of the carbies.

    It could be somewhere else in the fuel system, it could be in the induction or it could even be electrical.
  14. I recently had my carbies (2x) cleaned and balanced as part of an accidental overhaul. All in all it was less than $200 and my bike is better than ever. There was more to do on mine than just the carbies so it may be cheaper that way.

    Have to recommend that you do it that way rather than pull it apart, not get it back together then have to take it somewhere in pieces to get it working again...

    If you are in the eastern subs try In Tune in Ringwood, he was good.
  15. There've been some suggestions that the problem might be cr@p in the float bowl, and I'd be starting my investigation with that, as it's the easiest to check.

    Give that you have 4 CV carbies, I doubt that a pinhole in one diaphragm would explain the leaking fuel as the diaphragm only has an influence when the engine is running.

    Rather than disassemble the carbs (a horrible job on a 4cyclinder machine) I'd suggest the following:

    You'll find the carbies on the back of the engine. Follow your throttle cable down from the handlebars, under the tank, to the point where it attached to a linkage or splits into 4 cables which, in turn, or disappear into the "lids" of 4 metal cylinders (these are the tops of the carbies). A sidecover may have to come off to do this. Turn the twistgrip, and something is going to move under the tank - it'll be the carby actuating assembly.

    Do this job outdoors. Put the bike on the centrestand, or chock the sidestand to get the bike close to vertical. Put a towel over your gearbox and move the bike away from any naked flame. DON'T SMOKE. Don't put a trouble-lamp or any 240v lamp near the bike (a customer of mine now wears pressure bandages after a globe shattered over his workbench, igniting the carby he was working on and, subsequently, him).

    Right - now you've found the carbies. Each one will have a "float bowl" at the bottom, where fuel sits waiting to be drawn into the motor. The float bowl is the reservoir that holds fuel on its journey from the tank to the motor itself. Look for the lowest horizontal joint that runs around the carby - the aluminium dish below this joint is the float bowl.

    Turn the fuel tap to prime (so the fuel flows without needing the engine running) and try to isolate the carby that is leaking. If the fuel is clearly coming from one carby only (and you'll know because it is dripping from the underside of the carby) then that's the one to start with to start. Turn the tap back to "off"

    First step is to get all the goop down into the float bowl. At the moment, it is sitting in the seat of a tiny valve, stopping it from closing properly. We need to clear the goop from the valve.

    Each float bowl will have a drain plug at its lowest point - probably a brass screw (Your carbies are Keihin VP20s, but I can't find a diagram). If not, they may have a wire retaining clip that passes under the float bowl and holds it firmly up against the carby body.

    DONT CONFUSE THE DRAIN SCREW WITH THE FOUR SCREWS THAT HOLD THE FLOAT BOWL TO THE MAIN BODY OF EACH CARBY. You don't want to undo the float bowl if a drain screw is available.

    One at a time (starting with the one that appeared to be leaking, if there was one), remove each drain screw or unclip the float bowl. Turn the fuel tap to prime and flush some fuel through the carby. Petrol will run through the valve (taking the goop with it) and out of the drain hole (or, if you took the float bowl off, straight out the valve) - a couple of seconds flow will be enough. Replace the screw and repeat the process for the next carby.

    This should flush out any goop in the float bowl. You still haven't really cured the problem (cr@p in the tank) and, if you don't have a fuel filter in your main fuel line now is the time to fit one or repalce the existing one.
  16. thanks! for the help guys
    i pulled up my tank
    took off the air filter
    then under that there were the top of the carbys?
    i saw on the third hole tat fuel was stuck!....like2-3 cms high
    so i turned the fuel tap off. and let the engine running
    after a while the fuel in the top on carby's hole no.3 was gone and it seems to be running ok......
    im waiting for the weather in melbourne to chil down abit to take it for a run, its bee raining like crazy
    but i think maybe my carby's need a tuneup and balancing!
    any chance one of the spark plugs could be gone?
    one again thanks for all your help guys!
  17. Don't bikes have fuel filters?? (Just asking cause I'm new)

  18. The ones I've seen have a mesh filter integral with the fuel tap - it sits inside the tank. The mesh is pretty coarse on some. I always add a second in-line filter in the hose between the tank and the carb so i can see the amount of grit that is collecting.