Author Topic: No Spark  (Read 956 times)

Offline Saesneg Shaun

  • Newbie
  • Posts: 23
    • View Profile
No Spark
« on: May 04, 2022, 12:49:56 PM »
Hmmm, my k6 is not running.
It blew a main fuse and broke down on a ride last week.
The original fuse box was a corroded mess and just fell apart which I (wrongly) assumed was why the fuse blew.
New genuine fuse box from DSS fitted but still no joy.
I have no spark at the plugs. I've got 12.6V at the fuses but only 10.8 at the coils?

Anything obvious i'm missing before I start pulling the loom apart?

Offline K2-K6

  • SOHC Jedi
  • Posts: 4205
    • View Profile
Re: No Spark
« Reply #1 on: May 04, 2022, 01:07:56 PM »
Check inside the kill switch handlebar installation to see if it's got a problem there.

Also the electrical switch on the back end of ignition barrel can be vulnerable to years/wearing/corrosion too. The switching mechanism is brass pads and copper bridges spring loaded and swung around to make contact with this pins, you can carefully prize the plastic cover open to look inside if that's the area you pinpoint (do it over a tray or similar as the bits can piiiiing) then clean and reassemble with silicone grease or vaseline if you've not got any ;D

Obvious other elements are to just check all connection for obvious signs of corrosion.

Offline Saesneg Shaun

  • Newbie
  • Posts: 23
    • View Profile
Re: No Spark
« Reply #2 on: May 04, 2022, 02:56:33 PM »
Thanks K2-K6

Just dismantled the ignition switch and kill switch but no change.
They were both clean. I now have 11.8v at the coils so its improved a bit but still no spark at all?

Offline Oddjob

  • Grogu
  • *
  • Posts: 5467
    • View Profile
Re: No Spark
« Reply #3 on: May 04, 2022, 03:01:16 PM »
Also check the connections on the block connector the fuse box connects with. It's possible they were the fault in the first place and it was them failing and connecting with something it shouldn't that caused the fuse to blow.
Don't play stupid with me, I'm better at it

Offline K2-K6

  • SOHC Jedi
  • Posts: 4205
    • View Profile
Re: No Spark
« Reply #4 on: May 04, 2022, 03:18:40 PM »
Thanks K2-K6

Just dismantled the ignition switch and kill switch but no change.
They were both clean. I now have 11.8v at the coils so its improved a bit but still no spark at all?

Should be ok to spark at 11.8v without any real problems.  If that's a stable v there, then it suggests that the points or something related to them is an issue. 

Points are switching the earth side of the coil on and off, but if they stay earthed all the time (removing earth causes the spark) you'll get no sparking.

Basics, sure you've realistic points gap ? All little washers where the wires bolt to the points themselves look ok ? Any sparks at the points when you crank it ?

Offline Saesneg Shaun

  • Newbie
  • Posts: 23
    • View Profile
Re: No Spark
« Reply #5 on: May 04, 2022, 07:01:36 PM »
I checked the static timing and points. It all seems fine but I slackened them off and set them again and it now runs on 1 & 4.
Curious as i'd not touched the points since i've owned the bike but it runs, sort of!
2 & 3 still not sparking though. Its quite hard to set them as the centre cam that the points run off is really slack and can be rattled about on the shaft. I'm guessing it isn't supposed to be like that

Offline Saesneg Shaun

  • Newbie
  • Posts: 23
    • View Profile
Re: No Spark
« Reply #6 on: May 04, 2022, 07:08:12 PM »
Also check the connections on the block connector the fuse box connects with. It's possible they were the fault in the first place and it was them failing and connecting with something it shouldn't that caused the fuse to blow.

Could be. I did find a bodged wire soldered between the back of the 15A fuse holder and the brown/white wire from the ignition switch, gawd knows why as the original wire seems fine!

Offline K2-K6

  • SOHC Jedi
  • Posts: 4205
    • View Profile
Re: No Spark
« Reply #7 on: May 04, 2022, 07:11:24 PM »
Normally it wouldn't be rattling around, likely part of the problem for you.

Not hard to take apart, undo 10mm nut in centre, lift off the large "crank" nut, undo the securing screws that hold the whole points plate on and you can swing that out the way.

Then the cam (advance retard mech) can just be pulled off to look at it. It's got a location pin on rear so you can put it back in same place. Low risk to check it out and see if anything is out of place.

Offline Oggers

  • SOHC Member
  • Posts: 121
    • View Profile
Re: No Spark
« Reply #8 on: May 05, 2022, 02:51:18 PM »
A slack cam is no good at all! ATU weights should move out freely, springs free of any crud. Oil the pivot points perhaps. Also check out all screws holding points for 2 and 3 are tight, and re-check the gap. Clean the points. Check out all electrical connections to 2 and 3 points and check out the condensor -  with ignition on and if it sparks when you open the points gap, then a possible condensor problem. Have you a spark across the points when it turns over? 

Offline Saesneg Shaun

  • Newbie
  • Posts: 23
    • View Profile
Re: No Spark
« Reply #9 on: May 05, 2022, 03:29:38 PM »
A slack cam is no good at all! ATU weights should move out freely, springs free of any crud. Oil the pivot points perhaps. Also check out all screws holding points for 2 and 3 are tight, and re-check the gap. Clean the points. Check out all electrical connections to 2 and 3 points and check out the condensor -  with ignition on and if it sparks when you open the points gap, then a possible condensor problem. Have you a spark across the points when it turns over?

I can get it to fire but only on 1-4. I have checked the (new) spark plugs and 2-3 ins't sparking.
With 1-4 F mark lined up and the points gap set to 0.4mm the points don't break the circuit within the timing slots on the base plate.
Also I seem to have a problem where the points arm touches the cam as it doesn't look like the little contact arms touch the cam at its lowest point?

The cam nut wasn't tight but wiggle on the cam was just end float so that seems ok.
I don't get this, she's always been a sod to start but was running ok until the main fuse blew?

Offline K2-K6

  • SOHC Jedi
  • Posts: 4205
    • View Profile
Re: No Spark
« Reply #10 on: May 05, 2022, 03:44:04 PM »
Quick reality check, swap the two wires over coming from coils to points and see if the 2/3 coil fires then. It won't run at all but will show (with confirmed switching from the 1/4 points, if the 2/3 coil will make a spark) and which part of the system is working.

It sounds like the small rod that secures the points cam may be bent. As my routine above, strip the points plate and advance mech, then spin the motor to see if the rod is bent (if so it can give all sorts of errors in points gap) and at least give a baseline to work from.

Offline Saesneg Shaun

  • Newbie
  • Posts: 23
    • View Profile
Re: No Spark
« Reply #11 on: May 05, 2022, 04:11:21 PM »
Quick reality check, swap the two wires over coming from coils to points and see if the 2/3 coil fires then. It won't run at all but will show (with confirmed switching from the 1/4 points, if the 2/3 coil will make a spark) and which part of the system is working.

It sounds like the small rod that secures the points cam may be bent. As my routine above, strip the points plate and advance mech, then spin the motor to see if the rod is bent (if so it can give all sorts of errors in points gap) and at least give a baseline to work from.

Haven't swap the leads yet but i'm not so sure about the points cam now. The centre shaft runs true ish but theres lots of play in the whole assembly?
Couple of vids attatched

https://youtube.com/shorts/uI7pr4SpOKE?feature=share

https://youtube.com/shorts/wGs-SIJDHKI?feature=share

Offline K2-K6

  • SOHC Jedi
  • Posts: 4205
    • View Profile
Re: No Spark
« Reply #12 on: May 05, 2022, 04:29:01 PM »
Definitely something wrong with securing the advance mech there.

Agree the rod looks reasonably ok, but mech shouldn't be moving like that and with any real slack at all.

You'll get no real accuracy in timing, gap and dwell to set it up correctly. Should have a washer under the six mm nut to secure the bigger nut, is there anything there ?

Offline Saesneg Shaun

  • Newbie
  • Posts: 23
    • View Profile
Re: No Spark
« Reply #13 on: May 05, 2022, 04:44:01 PM »
Definitely something wrong with securing the advance mech there.

Agree the rod looks reasonably ok, but mech shouldn't be moving like that and with any real slack at all.

You'll get no real accuracy in timing, gap and dwell to set it up correctly. Should have a washer under the six mm nut to secure the bigger nut, is there anything there ?

Yes there is. The play is there with everything nipped up but not stupidly tight. When I stripped it down the 10mm nut was barely hand tight.

Offline K2-K6

  • SOHC Jedi
  • Posts: 4205
    • View Profile
Re: No Spark
« Reply #14 on: May 05, 2022, 05:21:48 PM »
Wondering if the rod is backing out of the crank which will release the advance mech ?

If that's happening, then the securing nut may be reaching thread end before tightening mech properly.

 

SimplePortal 2.3.5 © 2008-2012, SimplePortal