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DRZ400- Only push start

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by greals, Feb 11, 2009.

  1. My 2000DR Z400 slowly became harder and harder to start on crank until eventually it would not start at all but will push start easily. Once running it runs perfectly except it will not idle.

    I have a friend who has an identical bike so I am lucky enough to be able to swap parts. I have:

    Swapped coil and lead – no effect, works fine on mates bike.
    Had stator tested and charging coil rewound and new pulse coil at Small Coil Rewinds, Geelong. Mates bike starts fine on this new stator but mine still does not.
    Replaced cdi unit – no effect, works fine on mates bike.
    Swapped Reg/rectifier, no effect, works fine on mates bike.
    By passed starter solenoid (second 12V battery to starter side of solenoid), no effect
    Stripped down starter and inspected and tested by auto elec. – no sign of poling or malfunction.
    Checked cdi getting approx 12V on crank – ok.
    Unplugged, cleaned and replugged all connections.
    Replaced spark plug
    Hooked up second 12V battery so cranking speed is quite fast.

    The bike has had blinkers and side stand switch removed for some years.

    I have spent many hours trying to get to the bottom of this and am at my wits ends so any help would be very much appreciated. I am quickly coming to my next preferred option – a match for the bucket of bolts!!

    With thanks,

  2. B A T T E R Y ! ! !

    You have not said anything about the battery.
  3. he has.

  4. I'll bet you a long neck of home brew it's your battery. Test the voltage with everything off, if it's below 12.4 or so, you're in trouble!

    Also test the voltage after you have it running, should go up to around 14/15, this will ensure the bike is charging the battery, if not check alternator, regulator etc.

    Good luck! :grin:
  5. Time to check the resistance of the starter section of the wiring loom and stop blasting the sh!t out of it with a pressure cleaner.
    I also would have chucked a battery at it first regardless of how it cranks with a jumper battery hooked up.
  6. Sorry, I'll be less cryptic.

    He has said nothing about the voltage of his battery.

    As already mentioned, less than 12.4V is flat/dying. A fully charged battery should be around 12.8V.
  7. Do you have spark on cranking?
  8. I'd say the idle circuit in your carb is blocked.
  9. Negative, low/dead battery can cause idle problems on some bikes. Though it wouldn't hurt to give the carbies a clean, he seems to have missed that & wheel bearings! :p
  10. If it were a multi cylinder road bike with an automotive (car) style ignition system, I would agree with you. However, single cylinder dirt bikes usually run an ignition system that is totally seperate and independant of the charging system.
    In saying that, it wouldn't hurt to check the ignition coils on the stator. They may be not quite up to sctratch and require the extra speed generated by a push start.
    I could be totally wrong however. It has happened before :LOL:
  11. Thanks all for your replies and the thought you have given my frustrating problem. Sorry I haven’t responded before now, I don’t get home from work until after 7 and have been trying some of the suggestions in the interim.

    I am pretty sure it is not the battery causing the non-start on crank problem, although it may be responsible for the non-idle as it doesn’t hold charge well. To eliminate the battery as a source of the problem I have used 3 batteries, The bikes and a second car battery jumped to it and a third supplying power directly to the starter side of the starter solenoid (thereby by-passing the starter button and solenoid). It does not start and the voltage measured at the CDI during cranking is 12 to 12.5V and the motor cranks quite quickly.

    Given Roarin’s suggestion I thought I may have become ignition-centric, so tonight I removed the carby (bugger of a thing to get back on) and removed all of the jets and sprayed carby cleaner into them and blew them, and the passages, out. Unfortunately to no good effect.

    Also as Roarin intimated the most logical culprit is the slow speed coil on the stator, which is why I spent $450 getting it tested and rewound. When it came back and the bike still didn’t start to be sure it was ok I bolted it onto the aforementioned mates DRZ that started ok with that stator.

    The most interesting development from tonight’s fiddle comes from Devotard’s suggestion. Very early in this long sorry saga I tested to see if there was spark on cranking and there was not, but I have not had a look again since - but did so tonight. There is in fact now quite a strong spark on cranking. This is of course with the plug not under compression but is probably reasonable to assume there is also spark when the plug is installed and under compression.

    Hope you are not all as out of ideas as I am.

  12. Perhaps your valves are right out of spec. This will create hard starting, poor idling, but will still run with revs.

    Failing that, has the cam been in/out recently? Has the cam chain been tightened or replaced?

    You could swap carbies over to eliminate a whole chunk of things in one go.
  13. He he he he. It's too easy to get fixated on what you think the problem is. I chased what I thought was an intermittent electrical fault for weeks that turned out to be the main jet loose in the carb, vibrating itself tighter and looser as it felt like it, causing all sorts of weird misfiring :LOL: :LOL:
  14. Glad I am not the only one that gets tunnel vision at times.

    Will pull rocker cover off tonight and check valve clearances and state of cam and chain. Thought faulty auto decompression valve might be possible cause. I have only owned the bike for a couple of months, so I don't know if any work has been done on cams or chain recently.

    I do know I wish I had never bought the .......... though.

  15. Oh well, looks like I was wrong :grin: Now I am am wrong & out of ideas! Good luck Greals!

    Oh, & next time your in Melbourne, hit me up for that bottle of home brew!
  16. Thanks MV, might do that - is it as good abrew as the CX 500 was a bike?

    Found things pretty much in order under the rocker cover except less than .04mm (thinest feeler guage I have) clearance on inlet tappets so will try to source new shims tomorrow.

    Timing marks lined up as supposed to, cam lobes within spec with no escessive wear and auto decompression mechanism moves freely.

    I guess inlet valves not seating could explain problem - we will see with new shims.

  17. Had exactly the same syptoms with one a couple of weeks ago. Leakdown pressure was escaping via the engine breather.
    We pulled it down and found it was dusted and the piston rings were jammed in their grooves.
    It had decent compression too BTW. And ran pretty well.
  18. Thanks DSCR, not the sort of news I want to hear but may need to know.

    Sorry but not familiar with the term "dusted" - using the infamous phrase - "please explain".

  19. The air-cleaner had slightly breached and allowed dirt to enter the induction stream.
    The dust collected in the ring grooves causing them to jam and by-pass compression.

    The compression test was passable I think because the gauge was reading both cylinder pressure and crankcase bypass pressure.

    I hope it's not that greals but it was a curly problem which only really showed as a fault during leakdown inspection.
  20. EUREKA - the beast lives.

    I put new shims in (270 down to 260) and still couldn't get .04mm feeler into one tappet and just into the other but I put rocker cover back on anyway and she fired into life first touch of the button.

    So it would appear the tappet clearance had closed to the extent that the inlet valves were open even at full compression and this was enough to stop her getting enough compression to fire.

    I have pulled the 260 shims out and will try to swap for a 245 for the side I still can't get a .04 under and 250 for the other (std clearance .1 - .2mm) - might as well get it half right whilst I am on the job.

    Better than pulling the barrel off and replacing the rings!!

    Highlights the need to keep an open mind when tackling these problems.

    Now any one wanna buy a slightly used DRZ??????

    Thanks very much for all of your thoughts and help.