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Bike won't start, gearbox feels mushy. Advice needed!

Discussion in 'Technical and Troubleshooting Torque' started by Rayage, Feb 5, 2008.

  1. I spent the afternoon of my Christmas last year stranded on the side of the road with a 'box full of neutrals and a bike that won't start. The bike started cutting-out as I was pulling-over, and from there, it never started again.

    Anyways, fast-forward to the present. I need some advice on how to deal with my broken CBR250RR. I think the gearbox has packed-it-in. The gearbox now seems to shift positively (with a click) when I downshift. But upshifting feels like mush and it doesn't click as it should when it engages the next gear. I can't verify what's happening with the gearbox, since the bike won't turn-over anyways.

    Has anyone done or paid for a gearbox rebuild for a CBR250RR, and if so, how much did it cost you? Depending on the cost, I will either fix it and sell it; or I'll EBay it as broken or as parts. I would appreciate it someone can advise me on what I should do next. :oops:

  2. I think you're barking up the wrong tree.

    Gears wont select positively when the bike isnt running, as the cogs may not be aligned, and nothing is turning over at all to let them slip in. Rock the bike backwards and forwards a bit, and the next gear should click in.

    Next thing, why isn't the bike running? Is it seized, or just not firing? The gearbox should have absolutely nothing to do with your motor not running unless you're stuck in gear and the clutch isnt disengaging, or you've got a load of loose metal in her guts.

    Anyway, on 2nd thoughts, forget all that. Take it to a mechanic and get a quote.
  3. Actually the bike isn't stored with me at the moment (it's at a friend's joint who has space).

    I don't believe it's seized. It just kinda spluttered to death when I pulled over. I don't think it's an issue with fuel, as I recall filling the tank and only doing about 50km before it died. Maybe there's something loose or clogged in the fuel-lines...? But I'll have to check that there's fuel in the tank, just to be sure. I'll also have to try rocking the bike back and forth to see if the gearbox will engage gears properly, but I really don't hold out much hope.

    I'm not a mechanic but I like educating myself on mechanical stuff related to cars and bikes, but when this happened I remember performing a bad shift on the gearbox earlier in the ride, and after that, something just didn't feel right. The bike's done over 40000km so I'm not sure if the gearbox is meant to last this long before a rebuild.

    The only reason I can think of for the bike not starting is it thinks it's in gear, even when I hold the clutch down (kickstand up). I remember trying to do a rolling-start to see if I can start the engine without using the starter motor, and it kind of coughed for about 1/2 a second and wouldn't start.

    I guess I'll have to arrange to have the bike trailered somewhere to have it looked at.
  4. That will be your best bet.
  5. The most common reason for NetRider bikes not starting?

    Out of fuel. Then followed by the kill switch off. Then followed by flat batteries and other fuel problems. Just because fuel is sloshing around in the tank doesn't mean it can make it to the carbies...

    A gearbox fault won't make it splutter to a stop. If there was a gearbox fault, such as something broken, since the gearbox is in unit with the engine (they share the same oil and space) then the engine would have stopped with a big clunk and you wouldn't even be able to push it in gear!

    Don't fear the worst, that just never happens on a Honda. :)


    Trevor G
  6. It's been a while since I've done anything with the bike, and I can't remember everything that happened during and following the breakdown. But I'm pretty sure I checked the obvious things before calling a friend for help. And when help did arrive, it was a close friend (and rider) and his engineer friend (who rebuilds bikes) that helped me trailer the bike. I'm sure they would've slapped me silly for overlooking something simple - especially for dragging their arses out to the hills to pick me up on Christmas day! But like I said, I will go have another look this weekend just to make sure I haven't overlooked something.
  7. Just pointing out the obvious, but have you changed the oil?
  8. Nothing is wrong with the gearbox - Motorcycle sequential shift gearboxes also don't have synchro and cannot be properly changed when:

    1) The engine is not running, unless you rock the bike back and forth to change the position of the "dogs" which enable gear engagement

    2) The bike is not moving - see 1)

    3) The bike is coasting at 5 to 10 kmh and you are in a high gear

    Even if a selector problem had occurred, how could that affect the engine?

    Only if a piece of gearbox internals had broken and was jammed in the crankshaft area. Since the engine turns over (either on the electric start or through pushing) that hasn't happened.

    "I remember trying to do a rolling-start to see if I can start the engine without using the starter motor, and it kind of coughed for about 1/2 a second and wouldn't start."

    Engine isn't seized if it coughed or alowed you to push it in gear. You either don't have enough fuel or, if it is a diapgragm fuel tap (which only passes fuel when the engine is running or cranking) you might have a faulty diaphragm. This will prevent fuel entering the carbs.

    Here is step 2. (Step one is to make sure that you have PLENTY of fuel in the tank, not just sloshing around)

    1) Remove the fuel line from the carb bank - does fuel run out?

    No fuel = blockage, or a diaphragm tap, or insufficient fuel.
    Have you tried Reserve?

    2) If it is not a diaphragm tap remove the bowl and clean the strainer.

    3) If it is a diaphragm tap there will be a vacuum line from the inlet manifold to the fuel tap. Remove the line from the manifold.

    This part is risky: suck on the vacuum line, after first making sure no fuel is leaking from it. Fuel should now run through the fuel line.

    If the vacuum is not maintained (try sealing the end of the pipe against your tongue) for at least 4 to 5 secs you have a small hole in the diaphragm - there will probably not be enough vacuum to open the tap.

    In this case you can dismantle the tap and remove the spring from the diaphragm assembly so that it no longer shuts off the fuel.

    Check the strainer in the fuel tap - it could be blocked with rust.

    All the best

    Trevor G

    PS The advice/suggestion to change the oil, while good advice in itself, would have no effect on the problems mentioned.

    PPS You have checked the kill switch?

    Also remove a spark plug to check for spark while cranking the engine. The plug body must be earthed against the engine alloy, not on any painted surface.
  9. I do appreciate the advice everyone has given, but I still suspect gearbox problems.

    Today I went to my friend's place where the bike is currently stored and wheeled it out onto the road. Firstly, there's plenty of fuel in the tank. Good for at least 150km of riding. So it wasn't a lack of fuel that caused the bike to die. I checked the fuel petc0ck and it's set to ON. It was never moved from that position since it broke down (until today). Kill switch is set to RUN and with the key in the ignition at ON, I had my friend push me down the road.

    When I let the clutch out and gave it gas, it spluttered to life but it didn't actually rev at all. The engine made a kind of sound similar to when you go to the doctors and they stick a paddle in your mouth and tell you to go "Ahhhhh". Secondly, as soon as I let the clutch out and gave it gas, the rear locked immediately and I was just skidding along. I guess the sound the engine made is consistent because the rear tyre did not turn. As soon as I clutched in, the engine would cut out again.

    The bike is in dire need of servicing (even without this problem) and it could very well be something outlined by Trevor G. I think I will call a local shop and see how I go.
  10. when you missed gears ( as you previously said ) did you happen to over-rev it? it may now have bent valves. Do a compression test on each cylinder.

    If you have spark , fuel , and compression , there is no reason for the bike to not run , only engine timing ( which to my understanding isnt adjustable on a bike like it is with a car )
  11. And if you suspect the wrong area, you won't look in the right place!

    Did you actually pull a fuel line off the carbies to see if fuel would come out the line? If not, then that ius where your problem lies. You possibly have a shortage of fuel, even though the tank is half full.

    Now your next explanation is contradictory - are you talking about 2 different attempts? :

    The "aaah" sound is typical of when an engine is turning over with lots of throttle applied, even though it is not firing or running. You will get the same effect if you turn the key off as well.

    "Spluttered to life" is not the same thing.

    To push start a car or bike you need to be in second gear at least, sometimes third. Once you have enough push or roll speed (at least 10 kimh or a running pace) you "drop" the clutch, or let it out quickly. If you are not rolling fast enough or let the clutch out slowly it will end up skidding the back wheel as you also found out...

    If the rear tyre just skids (because you are in too low a gear) then the engine is not turning over and you won't get any "aaah" or "blurpetty" or "broom" sound.

    If the bike has not been running you need full choke and no throttle (otherwise the choke doesn't work properly, or at all in some cases). If it does not fire within a few metres then you either have no spark or no fuel.

    If it fires (you will hear exhaust noise) but won't rev up, that is because you are in a high gear which is too slow for the engine to run as well. Just pull in the clutch and it should rev freely.

    Sometimes when it fires you also need to turn off the choke (especially if it is not really cold) otherwise you can end up flooding the engine. A choking engine makes a typical "blurpetty blurp blurp" sort of noise.

    None of the above is worth trying UNTIL you check that fuel is reaching the carbs. The fuel line enters the carb body - just remove one line and watch for fuel to run out. If it doesn't, you have a fuel blockage or fuel tap problem as described earlier.

    If you are worried about identifying the vacuum line, it is usually a smaller size (diameter) than the fuel line and goes to the inlet manifold, not the carb body.

    There is another way to check for fuel - undo the drain screw at the bottom of each carb. This is usually a flush-fitting flat slotted brass screw. You usually only need to loosen it a couple of turns for fuel to run out via the drain hose. If fuel keeps running out for more than 30 secs you don't have a blockage.


    Trevor G
  12. Splutter wasn't the best word to use, suffice to say that the engine made some sort of noise that seemed to indicate signs of life.

    I did try a rolling start in 2nd gear after getting a decent push start. I don't remember how fast it was but my friend was running hard. It seemed to lock the rear just like it did when I tried using 1st. I made 3 attempts. Twice in 1st gear, and once in 2nd.

    If it's a fueling issue, then I will get professional help. It's not something I want to tackle, since I don't know what I'd be doing.

    Even it's a problem with the lines, I still do not understand why I could not get the starter motor to turn over. The bike seemed to have died as if it was starved of fuel (it kind of coughed to death), but I don't see why it should affect the starter motor. I had plenty of battery, as the headlights were on (I recall checking this, as I could not believe it was battery-related).

    I will give it another attempt this weekend with just the choke and no throttle. I will also try setting the fuel petc0ck to reserve too. But I suspect if it's the lines, this probably will not help. If there's no result, I'll get the bike looked at professionally.
  13. Did you check the fuses, headlights operate on a different circuit to ignition, which operates on a different circuit to the starter motor. Any shorting? loose conections? a loose ignition connection can give a weak spark, but I'd be thinking electrical if you can't get the starter motor to engage.

  14. Put the bike in 3rd or 4th or even 5th gear and just push it gently with the clutch out. That should turn the motor over slowly enough to prove that it isn't locked up. If you cannot move the bike (you will hear and feel the engine turning over) with the clutch out and in 4th or 5th gear you most probably have a hydraulic lock. Get it attended to - don't try any more starts.

    If it is locked up you need to remove all the sparkplugs and try again, in case leaking fuel has actually filled one or more combustion chambers - since petrol is incompressible, the engine won't turn over if that has happened. This might answer your question below.

    If you can move the bike when it is in gear and with the clutch pulled in that shows that you don't have a locked-up gearbox problem. It will be stiff to move because a bike clutch usually has a lot of friction compared to a car.

    If both those tasks succeed, try push starting in 3rd gear. High revving engines need to be push started in a higher gear, otherwise you are just trying to turn the engine over faster than is possible when pushing.

    The higher the gear, the less likely for the bike to skid when you let the clutch out. Remember to let the clutch out quickly - "drop it" in other words.

    All the best

    Trevor G

    PS Please let know what it is...
  15. Getting a friend to help me check the bike out. He's not a grease monkey but checking the lines and that sorta thing isn't an issue for him.

    I take back what I said about the gearbox. I'm more convinced than ever that it's not the gearbox. When I pulled over when the bike was cutting out, I remember just clutching-in and pulling over. I'm sure I wasn't in 2nd or even 3rd gear. There wasn't much point shifting back down through the gears as the bike wasn't starting at the time. This explains why the gearbox felt mushy. I never realised this in the 1.5 years I've been riding (I always thought you could shift right through). Thanks Trev for pointing this out.

    My friend is going to try a few things to get it started - most of which have been advised here (If I haven't already tried). Will look at fuel lines, the carbs, the fuses etc.

    Hopefully things will go will this weekend. I really hope it's not hydraulic lock and I've stuffed it trying a rolling start in 1st and 2nd.
  16. PM me for my phone no if you think it might be useful.


    Trevor G
  17. Should be alright mate, I trust my friend who's gonna have a look at the bike. Like I said, he's not a mechanic but he's done work on both is car and bike, so I reckon he knows his way around. If it's something he can't fix, it's probably got to a point where it has to go into a shop to get fixed professionally.
  18. After all this faffing about, it turns out it was all to do with a flat battery. :oops:

    My friend brought a multimeter and a spare battery to see if there was any juice left in my battery. It turns out that there was about 5.5v on the battery. :-k Anyways, it turns out the the spare battery wasn't holding charge either. My friend charged his battery overnight and it was down to 11.5v by midday today. So we upped ourselves over to A1 and bought a new one. Got the acid in it, sealed it up, waited 30mins, popped it in the bike, and she fired first go. :| :) :grin:

    It sounds like it might be the regulator that's not charing the battery properly. We didn't get time to test this, so we'll leave it till next weekend. Still not sure why the bike cut out, tho it could be that the battery had lost too much juice before and during the ride and she cut out. My friend said that the lights draw a lot less power, so that's probably why the lights were on even though I couldn't get the starter cranking. Given that on the day it died, I was able to start it as per normal seems to indicate that, despite my 50km-odd I travelled before cutting out, that the battery was not being recharged as I rode.

    Anyways, thanks everyone for your help and a big thanks to Trevor G for his persistent help :wink: . I learnt a great many things as a result of this 'ordeal'.