How do I test an electrical system?

[Graeme M]

I've never had to worry about that before, but I have reassembled my IT175G and wired it up and... no spark.

Now, I *think* I've wired it correctly. I followed the wiring diagram but I've removed the full harness and have the wires from the mag connect to the CDI as they are supposed to and set up an earth for the various black wires floating around. As far as I can see, both kill switch and ignition switch simply closed the circuit to earth when in Off position. So pulling the ignition switch out should make no difference. And not conecting any lights etc would have no effect either. So...

How do I test the magneto and ignition coil? I have a tester but I have no idea what the various dials and readings mean. What do you connect to what? Or is this something you can't easily explain on a forum?

My tester looks just like this one:

[Snowy 76]

Nice looking tester Graeme.

[Graeme M]

It is, isn't it? I often just get it out and look at it.

[crs-and-rms]

i could copy a suzuki video that would show you how to test it ,you would still have to have the specs for your bike

[Graeme M]

That would be great. I have the manual and the specs.

[yzhilly]

G'day Graeme have you got the specs ? and a Manual . I have a IT200 book i can scan the Elec test pages . I had problems with mine ,fitted a spare stator and tested everything . It was the plug cap . I bought 2 new ones for $7.00 each and carry one in the toolbox . Hilly

[SUZUKI311]

A good source of info i have found to be Bert Neville from Small Coil Rewinds in Geelong- o3 52 788454, Bert has been around for ever and knows his stuff, and is also now the owner of IMRIE testing equipment, which manafacture some of the easiest to use electrical testing equipment for bikes and small engines.

[crs-and-rms]

send me a pm with your details Graeme and i will burn you a copy and send it to you

[Lozza]

Your better off with an analog multi meter, and you will also find a Peak Voltage Adaptor(that Bert kindly charges $75 for a $3 capacitor and a $3 diode ) the adaptor will let you spot the trigger pulse while running, the multi the AC coming from the stator.

You will only need the OHMs (resistance) and ACV has a solid line with dots above it. If you see OL displayed move it up to the next scale. AC voltage will be off the stator(while running), OHMs will be read for everything else. Explaining how to use a multi is to time consuming for words. However it it just basic electrical principals V=RI where V=volts R=resistance in Ohms I= Current in amps
HTH

[yamaico]

Hi Graeme,
Was the bike running before you pulled it down? If so, and you have repainted the frame, chances are you have an earthing issue. Make sure that you scrape the paint off where the ground wires go, and preferably use a star washer between the lug and the frame. Also scrape the paint off under the ignition coil mounting bolts. You mentioned that you had grounded all the black wires, I hope that doesn't include the black low tension wire on the ignition coil, as that one (from memory) goes to an orange? wire from the CDI

[Viper666]

Go here http://www.yamahait.com.au/files/1980%20IT175.pdf then go to service data at the bottom of the list.

Best to do all this with the flywheel off. As stated before EARTH is critical. Make sure all earth leads, high tension coil (Spark plug coil) etc have good contact with the frame or engine. Also the engine has good contact with the frame (No paint or powder coating between frame and engine at least at one mounting point but preferrably all). With the multimeter on the lowest setting, probably 200 ohms, short the leads together. This is a referrence, they should read about 0.1 or maybe 0.2. Anymore and you may have crook leads or flat battery. Then test the engine to the frame this should be under 1.0 ohm preferrably the same as your lead test but allowing 0.2-0.5 ohms. Then test the the black wire from the flywheel loom to bare metal on the frame. This again should be under 1.0 ohm preferrably the same as your lead test but allowing 0.2-0.5 for the earth lead itself then if it is over 1.0 ohm start there first. While the test leads are still conected gently move the earth wire where it conects to the body if the reading alters you may have an intermittent break.

Assuming good earth everywhere test the pulse coil (Little bugger) White/Red wire to Black, should be 12.4 ohms +/- 10%, (No reading means open circut-broken wire or stuffed coil) while the test leads are still conected gently move the wire where it conects to the coil, same test as earth. Then test Source coils, red wire to black 13.6 ohms +/- 10%. Change meter to 2K or 2000 ohm setting and test brown to black, 420 ohms +/- 10%. Plug coil should be primary to earth (Back to 200 ohm setting)(Lead from CDI into coil) 1.0 ohm +/- 10%, secondary (20k or 20000 ohm setting)(Plug cap to earth) 5.9K ohms +/- 10%.Dont worry about the lighting coil it doesn't affect ignition but if you want to test it (200 ohm setting) 0.48 ohms +/- 10%. Again do the wiggle test for all.

As for the CDI, best to borrow a good one if all else checks out as there is no simple test for a CDI.

All else fails take the lot to Bert and he can spin it up on a machine and check everything, pretty cheap too.

One more thing, I had my pulse coil fail so had no spark by kicking but would spark if pushed in gear.
Pull your plug out, put in first on a stand and spin the wheel as fast as you can or push in gear. If you get spark then it is a sign of stuffed pulse coil if spark good or crook earth (Maybe) if spark weak.

If you want to talk my number is 0427 334 186

Viper666

[Graeme M]

That's some excellent info there, thanks a heap. I'll have a good look on the weekend and see what I find. The earth might be well worth looking at to start. And no, I'm not a complete goose, the black wire from the coil goes to orange 

By the way, it's never run while I've had it. It was a very sad basket case type buy, although largely complete. Looks very nice now though!

[Viper666]

P.S. Agree with Lozza wholeheartedly

Your better off with an analog multi meter

Lets you look at things in real time espaecially the "Wiggle test".
Digital meters are very pedantic and can give referrence values rather than true but digital are the best for quick checks just to get readings or O/C etc.

My suggestion to anyone who is not familiar with the use of a multimeter is to get 2. A self ranging digital one, dont have to know what ohms scale to set on when measuring resistance, and an analogue one for double checking and teaching yourself about ranges.

If you dont know what the reading should be, or it is close to the limit of a range the trick is to start at the top and work down. ie start at the highest range, 20MegOhms or 2MegOhms (20,000,000 or 2,000,000 ohms) and if you get a reading (Probably look like a short "000") keep switching down till it reads within the scale.

Viper666