600 ss missfire

Discussion in 'Supersport (1974-2007)' started by fattaffracingco, Oct 26, 2013.

  1. can anybody shed any light on this ?
    I had misfire on rear cylinder intermittantly,i parked it up for a month and on restart and I had no rear cyl spark, I put a multimeter on the pick ups and the rear one came up as a dud ! I purchased new pick ups and wiring from my local ducati dealer and replaced them
    still misfire on rear cyl but only when I rev bike there is spark on idle
    I have switched /swapped around the ign modules,the coils,the leads and plugs but cant move the problem from the rear cyl,my mate is a sparky/ tech and we have both tested these items and they all come up with correct values a la Haynes manual !!!
    i',m scratching me head a little bit now, has anybody had a similar prob ??
    oh yeah the air gaps have been set pretty accurate and the rear cyl pickup air gap is spot on,the other is a little tight but that's on the good cylinder(front)-my next thoughts are the loom !!! gulp !!
    any advice would be very helpful
    thanks in advance- chris fattaff
    bike is 94 carb model
     
  2. The previous owner had a similar problem with mine, a new coil did solve it, does sound like an intermittent wiring fault, bad earth or faulty connector somewhere.
     
  3. I have some spare coils I use for testing, so if you want to borrow one...........

    AL
     
  4. Have you replaced the spark plugs?
     
  5. hi al,i have swapped the coils over to try and move problem to front cyl but to no avail,its always on rear cyl, its permenantly missing on throttle blip(with spare plug on lead and earthed u can watch spark disappear) which should make it easier to diagnose but no !
    if coil was faulty the prob should move with coil I wud have thought-all connections look good also
    thanks for offer tho- I might do
     
  6. Will it rev up or is this just when you blip the throttle? Have you look at the rec/regulator, they can do funny things.
     
  7. Make sure the wiring at the connectors on the CDI units isn't sparking / touching on the underside of the tank.....
     
  8. thanks al I will check this again,but im sure it does it with tank propped up
     
  9. as soon as revs rise from idle it loses rear cyl spark whether blip or gentle increase
     
  10. Have you tried swapping the pick up coils? They do fail on occasions. You can get replacements from Electrex for about £25 from memory.
     
  11. I belive there was a similar question asked in PSB a few months back now I come to think about it and answer was as nick said.
     
  12. they r brand spanking new from ducati Cardiff, I have re tested them and all values come up good,old ones showed up a dud as per first post
    yes I have swapped and changed plugs
     
  13. bump - anybody else had similar prob ?
     
  14. Have you looked at the belts? I had a similar problem where one of the belts was slackening off and throwing the timing out a little. Turned out to be the belt tensioner bolts were standing too proud and the belt was rubbing them and loosening them off.

    I know lightening doesn't strike twice, but if you've checked all the usual electrical stuff and it's still just on the rear cylinder.....Just a thought.
     
  15. well worth a look,i will do so when I get chance,ta kenoir
     
  16. reading whole thread it only points to ignition related loom now but am also thinking that despite rear pick-up being new it could still be at fault or maybe the wire run from it has been snagged somewhere causing it to earth or go open circuit intermittently.
     
  17. not far off there me old guvnor !!!
    ok the bike is fixed !! to conclude the thread in case of thread search here goes--
    righty -when installing the wireing which comes with the pickups (genuine parts) in order for the wireing to pass thru the casing hole/rubber bung you need to push spade connectors out of the double clear block connectors connected to the cdi units ,the haynes manual states that spade conns must be put back in exactly the same positions and boy were they right !!!
    yeah u guessed it, i crossed the rear cylinder spades over when pushing them back into the multi plugs,very easily done when both spades are the same size ,and are fiddly to push in multi plug especially if u are holding clear plug upside down !!! doh !!
    so thats the result if u do-loss of spark on that cylinder- my mistake was spotted by local mechanic and wise old sage Rhydian of BANNER MOTORCYCLES OF SWANSEA, the problem did have us all head scatching for a bit tho
    so if u change the pickups be careful and take yer time, i hope my openness about ferk upps helps someone else further down the line-many thanks to all who replied,this is a great forum and sharing knowledge makes the differance to all,thanks chris
     
    • Like Like x 2
  18. Good to hear you're sorted the problem, I hate wiring, sounds like an easy mistake to make:mad:
     
  19. Good news
     
Do Not Sell My Personal Information