The bike hasn't been fired up for about 3 years and after giving it a full service in the last few days I tried to get it started, it did run for about 20 seconds; then it started to fire out loud "pops" and other strange noises. Tried a few more times in between charging the battery; then I pulled the plugs off and they were soaked in petrol as expected. I do have a new set of plugs, but would rather burn the petrol off the "old" plugs (I've done less than 1000 miles with them on) and get the ignition system sorted first, then I can replace the plugs.

Following the Haynes manual, I've tested the Ignition HT coils and Pulse generator coil with my Multimeter (same as this):

and came up with these results:

Front Coil
Primary Resistance - 03.3 (measured @ 200 ohms) (Specification range - 2.5 to 3.5 ohms)

Secondary Resistance (@ 20k ohms)
With Plug Caps - Nothing (Multimeter remained on 1) (Specification range - 14.0 to 25.0 K ohms)
Without Plug Caps - 13.94 (Specification range - 11.0 to 14.0 K ohms)


Rear Coil
Primary Resistance - 03.3 (measured @ 200 ohms) (Specification range - 2.5 to 3.5 ohms)

Secondary Resistance (@ 20k ohms)
With Plug Caps - Nothing (Multimeter remained on 1) (Specification range - 14.0 to 25.0 K ohms)
Without Plug Caps - 13.75 (Specification range - 11.0 to 14.0 K ohms)


Pulse generator coil - 407 (measured @ 2000 ohms) (Specification range - 450 to 550 ohms)


According to Haynes, these results indicate that the caps are faulty but the HT coils should be ok; but maybe the Pulse coil isn't? Is the 407 reading too far off the range?

Can someone tell me if any of this is right please?

Also, which NGK caps do I need? I've seen these on eBay, but as it says it's for 10-12mm spark plugs, I'm not sure they'll fit.
eBay item number:
271643288546
http://www.ebay.co.uk/itm/NGK-SD05F-Spa ... 3f3f33a3e2

Are there any other caps that fit on the NC30/35?
Also, any ideas where to get a replacement Pulse coil?

P.s. Following the Haynes manual to the letter did allowed me to test all the above, but it would've been good to know beforehand that the caps wouldn't be reuseable once they've been pull off the HT leads, as the O.E. caps aren't the screw on/off type!!!

Plug caps should measure approximately 5000 ohms each. You should have used the 200k ohm range to measure from cap to cap, 20k ohm is too small. My NC30 pulse coils each measure 398 ohms and engine runs fine.

Try cranking the engine with clean plugs resting on the rocker covers and check for reliable strong spark. No spark, then ignition control unit maybe faulty or no power, check for power to the ignition control unit. Good spark, then try starting again with cleaned old plugs if you prefer, but disconnect the rect/reg first A rect/reg fault can cause an over-voltage condition which can upset the ignition control unit once the engine has started, your "then it started to fire out loud "pops" and other strange noises".

Thanks magg, electrics was never my forte; a bit of a rooky mistake I guess.
Any idea if those NGK caps can be used on 8mm plugs? I'll have to replace 2 of them regardless, since I pulled them off the HT leads!

At least the pulse coil should be ok... I'll do some more testing and then maybe try get it fired up again.
How do I check for power to the ignition control unit? An idiots guide on how to use the multimeter for this, would be great!
Thanks.

Others on this forum including Rick Oliver may be able to make a recommendation regarding spark plug caps or you could try NGK SD05FM, they might work.

Test for spark with clean plugs resting on rocker cover first.

Thanks again maggs.
Tested the caps again, this time @ 200k ohms and got the correct figures. It seems the caps were fine after all. DOH!
Strangely enough, I got the HT leads back in the caps which were removed earlier and it showed on the multimeter that there's still life in them; so I got the old plugs back in, unplugged the reg/rec and started it up again, after a couple of tries it fired up! Got it up to temp, switched it off, reg/rec plugged in again and it fired up and run fine for another 10 minutes.
I've ordered 2 new NGK caps and will see if they'll fit ok, if they do I'll get 2 more!
I guess I was a bit impacient with it.

Occasionaly it doesn't seem to tick over perfectly, but for now I'm just happy I got to hear that lovely v4 again!
Cheers.

Suggest you check the battery voltage when the engine is running at 5000 rpm, should be minimum 14 v dc and not exceed 15.5 v dc. Just a precaution to confirm no rect/reg problems.

I did remember to do just that, it showed 14.6 if memory serves me.
The reg/rec was replaced with a new unit about 4 years ago, so it's unlikely it would be kaput. As you say though, always good to do the check and it is easy enough!

Quick update on those NGK SD05FM caps; they fit and work just fine and are simply screwed on.
I got them from here: http://www.ebay.co.uk/itm/181480217421? ... EBIDX%3AIT

In order to keep water away from the plug well, I've cut the "collar" from the O.E. caps and fitted to the NGK ones; it's a nice snug fit, so I reckon it'll be fine!

P.s. don't pull on the HT leads too hard kids, you've been warned!

A quick way to take electrical measurements on a bike with more than 1 cylinder is to compare results.

Measure each coil, lead, pick up, diode, etc from each cylinder and compare values.
Seldom will they each fail to to same level, in fact normally they will go short circuit or open circuit.