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Need karma? Help - Bike wont start

Discussion in 'Technical and Troubleshooting Torque' started by Haggismaen, Jun 14, 2006.

  1. Bah. Could've seen this coming a mile away. In an effort to fix my previous problems I decided to give the bike a good workover. Took off the carbs, cleaned the bowls, jets and air screws with carb cleaner and did a bit of other work.

    Now, I reassembled everything (not saying I did it correctly, but we will get to that) and tried to start the bike. It turns over, but does not want to start. Now I will run through everything I have done so far:

    - Choke and no choke, does not affect it.

    - Battery fully recharged (though it is beginning to run down again due to lots of cranking).

    - Oil level is good and looks clean.

    - Fuel is readily available (checked fuel tap), fuel is also reaching carbs as tested by draining float bowls (though I have not done this with the fuel tap on as of yet to check quality of fuel flow).

    - Drained float bowls, did not have any effect.

    - Checked airscrews and tried them in different positions, no effect.

    - Tried it with air filter both on and off, no effect.

    - Used new spark plugs (correct ones), no effect. Checked spark plug gap on both new and old ones so thats OK.

    - Sprayed some carb cleaner straight into carbies while cranking, no joy.

    - Tested compression, however I do not have a guage so I did the guesstimate method of placing thumb/finger over hole while cranking it over. Supposedly you should not be able to keep finger on the whole. While I can't say that I kept my finger on it (couldn't actually form proper seal with finger/thumb), the pressure seems fairly weak (however this is a novice's assessment; also I tested its compression before I worked on it with a guage and though, while not as high as it should be it did seem stronger than it is now). Can also feel pressure at the exhaust.

    - Checked for a spark on both cylinders. Now people say you should see a nice big fat spark but to my novice eyes I only got a very small one, is there a better way to tell (maybe some pictures of what it should be like? Short of some electrical testing equipment which I do not think I have).

    Do you think it's probably a spark or compression issue? Perhaps it might be wise to throw out some ideas (no matter how noobish, because those are probably the sorts of mistakes I would make) about what could cause poor compression and/or spark as a result of cleaning/removing the carbs and things that may have been effected near by (I didn't touch the cylinders apart from spark plugs/leads).

    I might go get a compression tester to get an accurate reading and might test the valves using the oil in spark plug socket test.

    Go on, help a noob and get +1 karma.
  2. 1. Did you attempt a push start ?

    2. CRC Aerostart starts engines instantly, direct some of the spray at the air intake whilst the engine is being cranked.
  3. something i learnt on the weekend, you can also use, hairspray, deodorant, flyspray, etc. basicaly anything with the little flamey thingy on the can (or that works in a lemon cannon). not as combustable as aerostart but still does the trick.
  4. i hope your handle bar/indicator repairs went well as for the starting issue it was working before you dismantled the carburettors right?

    so i doubt the motor has lost compression all of a sudden.

    you say you changed the carburettor mixture screws did you by any chance record how many turns etc changes you made, if answer is yes try to set everything back to the way it was when it was running.

    i hope this helps please read and think through what i write as i am no proffessional mechanic.
  5. I thought that was for when your battery is either dead or close to it. However I did try one just then to no avail.

    Tried the carb cleaner in the intakes, same principle, though whether or not it is as effective, who knows.

    Got replacement handlebars, but need to drill hole in them for throttle controls. Very much my secondary concern at the moment. The engine would start before I attacked the carbs (though it was not running well at all, hence the carb attacking).

    The jets in the float bowls were put in exactly as they were (no room for anything different). I have tried the air screws (mounted externally) as they were before, and in various different positions.

    Thanks for the tips guys, I know (hoping) it is probably something fairly minor.
  6. I'm sure if you look hard enough someone is selling karma on ebay... Its a freaky auction house... I tried rental space / advertisning space once... never again... :shock:
  7. Allright for the sake of diagnosing lets assume that I have sufficient compression (which I should, as the bike ran before this) and a spark (which I do, in both cylinders).

    What problems could there be with the carbs (as in something I have put in wrongly while reassembling) that would cause this failure to start?

    I have tried adjusting the air screws. The jets didn't seem like they could be adjusted, and I put them back in as they were anyhow.

    Anybody have anymore ideas? Keen as mustard to get back on the road.
  8. Use a car battery to try and crank it, normally has a bit more juice for it so it should make it easier to start.
    If you are doing that and using carb cleaner into the air intakes, it should start, if it isnt then i would have to say spark is your problem, or something worse.
  9. I find that after you do a carb rebuilt you need to crank over for a while.

    For some reason, even if you get fuel in the bowls, it tends not fire up immediatly.

    Hold you fingure on the start button and hold the throttle in varies positions.

    Get the battery fully charged first.