Testing coils

[Tone]

Bike (89 GSXR 750K) is running like crap again,hard to start,rough idling,blowing some dirty smoke and backfiring under load,also shooting a few flames at rest with revs raised.Figured I'd try and check the coils so I pulled em out and whacked the multimeter on em
Set meter on 200 ohms and checked primary resistance (I'm assuming this is between the 2 posts on the coil) and it read 0.6,which I figure is very bad.
Set meter on 2K and connected to + post and plug end of lead (assuming this is secondary resistance) for a reading of 0.231 which is not making any sense to me.Am I doing this right?
Manual reckons 2.4-3.2 ohms for primary and 30K - 40K for secondary.
Could this mean plug leads are shagged?Plugs look good but pulled one, grounded it and spark was pale yellow,nothing blue about it.
Probably could use a new air filter as well but can't help thinking coil problem.
Anyone know how to interpret these readings?
Thanks lads.

[megareg]

For primary resistance, leave the range selected to 200 ohms, measure between the two spade connectors, on my Kat, the colours are (from memory) orange for the positive and black or black/orange for the negative, which will be from the ignitor, for the secondary, measure from the plug cap to the FRAME/ENGINE, not the + or any of the spade connector.
The reading you have from the plug cap to one of the spade connectors of 0.231 ohms tells me you have a coil fault, maybe someone can swap the coils for known good ones to check....

[Tone]

Thanks Reg,re-checked from plug cap to frame and still read 0.231,not sure what's going on there.Also did a signal generator test on 200 ohms and got 26.2 which is nowhere near the 130-180 range stated in the manual.This of course,is assuming I'm doing the test right,of which there is no guarantee[:I].
Would a crapped out signal generator cause the running problems mentioned in the original post?
Still would seem to have dodgy coils though,with those readings.
Connections from ignitor to coils seem OK,as in no broken wires.
Cheers again.

[oldskool]

are you in melb? I got a suzuki coil tester , check your valve clearance!

[megareg]

I reckon the coil is crapped out, are the readings the same on both coils?? if so, it would be unusual for two coils to be stuffed, I'm not too familiar with the electrics on the gsxr, are the coils in the plug caps?? hmmm.... let me look at a wiring diagram... google is my friend...

[Tone]

Oldskool:nah mate Syd...and I never thought about valve clearances.Would explain the crap running but not the bad meter readings on the ignition bits...sorry for my mechanical ignorance but I'm trying to learn,albeit late!

Cheers

[megareg]

Back again... had a look at alpha parts to see the setup you have, 2 coils, 2 leads out of each coil, then had a look at my Kat's wiring diagram....

To measure the secondary resistance, you will have to set the scale on your meter to 200K or so, I use a Fluke meter, it auto ranges, you then measure between the plug caps, i.e. 1 and 4 then 2 and 3, that should give you around 40K resistance.

To measure the primary resistance, set the meter range to 200, take the spade connectors off the coil, on my Kat, the colours are Orange/White (the positive lead, and is on both coils) and White (the wire from the ignitor) these are the colours from the coil that fires plugs 1 and 4, measure across the 2 spade connectors, you should get around 3 ohms.

While you have the spade connectors off the coil, measure between one of the spades and the frame, there should be an open circuit there i.e. high resistance (change the range of your meter to the highest resistance). Then measure between one of the spades and the plug caps, you should have high resistance there too, according to what I see of the diagram...

And if you can borrow another set of known good coils, try that!!

Hope that helps... my 200th post too!!

Cheers

[Tone]

Reg,yes I'm getting the same readings from both coils which would be a bit of a coincidence wouldn't it?
Cheers

[megareg]

Yeah, it would be unusual, it seems like you should be looking elsewhere, try making sure all connections are clean and tight, make sure your earth (negative wire from battery to motor)is good, and yes, valve clearance too, although you may find that the problem may change with the temperature of the bike, oh, and have you done a compression test?? look at carbies too, i'm sure others on this site would have a better idea than me on the problem, just a bad time of the year...

Cheers and good luck.

[Tone]

Onya Reg,I'm reluctant to point blame at the carbs as they were only recently overhauled and bike ran like a charm after that.Bugger all k's done since that work.
I'll see about getting a compression tester and while it's all apart may even venture into valve clearance check (big gulp).And will check connections when I get a bit more time...fucking christmas with relos and kids is pretty taxing on any time I get, especially as it takes me fucking ages to do any type of work on the bike.As I'm sure it is for anyone!
As for temp while checking stuff,I got the mrs' hairdryer on the coils before making any readings.
Thanks for your time bud.

[Tone]

Don't know why,but after checking and cleaning connections,blowing out breather tubes,cleaning air filter and re charging battery I put the bugger back together with little hope of anything being for the better...but!!! The bastard started first click on the starter and idled away with no popping,missing or farting.Got me fucked after the dodgy readings on several components after the last few days.But hey,can't complain.
Big cheers to Reg for the time/advice and oldskool for the offer.Ta lads.

[megareg]

Good to hear Tone, may have been a bit of crap on a connection then and all is well.
Cheers