'93 25hp 2 stroke...violent sputter

[99yam40]

I would think that it cannot be replaced if they do not sell them separate.

You have said in the past you have a service manual for your motor, so it will have the test procedures and specs you should get when testing along with what test equipment is needed.
Get the DVA to read peak voltages if you are not buying the special meter for reading these ignition peak voltages so t=you can compare to the minimum listed in specs in manual.

Oh and you do not have to pull flywheel to read the pulser and charge coils as you read them on the wires going into the CDI and then read the outputs of CDI to the coils feeding the plugs.
Resistance is just one test do with out motor running, I trust the voltage reading a lot better and can be taken while cranking and while running when problem shows up

[Jason2tpa]

Update Please Advise

Hooked up the multimeter (resistance mode) and used the exact procedure in the service manual. For measuring the primary coil the meters positive clamps to the coil positive and the meters negative to coils negative. For measuring secondary coil the meters positive clamps to the coil negative and the meter negative clamps to the high tension cable (which is located in the plug).

Here are the results:

#1 & #2 coil packs had same measurements
Primary coil = 0 (.096-.144)
Secondary coil = 2.3 (1.68-2.52)

Is it just coincidence that both primary coils for both coil packs measured zero?? Ive hooked up the meter exactly as the manual. And yes, i switched meter between different ohms setting. Im at the boat now so if you suggest something else i can try please let me know asap!!

[99yam40]

your meter may not be able to read low Ohm values.
This is another reason I say to do voltage readins

[Jason2tpa]

It values three decimal places (0.000). I'll try the voltage. Manual doesn't list spec values. Or am just checking for any power going to coil packs?

your meter may not be able to read low Ohm values.
This is another reason I say to do voltage readins

[99yam40]

then my guess is you do not have a Yamaha service manual for your motor

But even an after market should have specs on peak voltages on all the coils and CDI output

[Jason2tpa]

I have both owners and service manuals for my specific year and model. No voltage specs listed. I'll do some fishing around online.

But back to the results i got. Is it possible the primary coils for both coil packs are bad? I dont know. I kinda feel i did something wrong, but I didn't. Its a simpe hook up as i described. Cant mess it up.

then my guess is you do not have a Yamaha service manual for your motor

But even an after market should have specs on peak voltages on all the coils and CDI output

[boscoe99]

Update Please Advise

Hooked up the multimeter (resistance mode) and used the exact procedure in the service manual. For measuring the primary coil the meters positive clamps to the coil positive and the meters negative to coils negative. For measuring secondary coil the meters positive clamps to the coil negative and the meter negative clamps to the high tension cable (which is located in the plug).

Here are the results:

#1 & #2 coil packs had same measurements
Primary coil = 0 (.096-.144)
Secondary coil = 2.3 (1.68-2.52)

Is it just coincidence that both primary coils for both coil packs measured zero?? Ive hooked up the meter exactly as the manual. And yes, i switched meter between different ohms setting. Im at the boat now so if you suggest something else i can try please let me know asap!!

To measure very low resistances first simply hold the two probes of the multi-meter together. Let's say the reading is .4 ohms. Make a note of this. This is the resistance of the meter itself.

Then measure the resistance of the primary coil. Let's say it is .490 ohms.

Subtract the .4 from the .490 and the result is .09 ohms.

The Yamaha service manual indicates that the resistance of the primary coil is to be .09 ohms, plus or minus 15% at 68 degrees F. But I suspect this is a type and that it should be approximately .9 ohms or so.

Now keep in mind that .09 ohms is almost no resistance at all. Which is as it should be in the primary side of the coil itself.

The secondary coil is a different animal altogether. SM indicates the resistance is to be 3500 ohms plus or minus 15% at 68 degrees F. The values that you show are on the low side. If what you are reporting is ohms.

Maybe read up some on coil testing. Plenty of stuff on the inner web.

Dan's Motorcycle

[Jason2tpa]

Thanks Boscoe good info. I did make sure to note the resistance in the meter prior to testing the coils. Zero. And you make a great point. However, in this situation it's a moot point because regardless of what the meters resistance is the primary coil measured zero...to three decimals places. So it didn't even record a meniscal amount of resistance. The method I described in detail...as far as which probe goes where...did I measure this correctly? Like I mentioned I followed the manual. Is it strange both coil packs measured zero...primary that is? And yes, I was reporting ohms.

To measure very low resistances first simply hold the two probes of the multi-meter together. Let's say the reading is .4 ohms. Make a note of this. This is the resistance of the meter itself.

Then measure the resistance of the primary coil. Let's say it is .490 ohms.

Subtract the .4 from the .490 and the result is .09 ohms.

The Yamaha service manual indicates that the resistance of the primary coil is to be .09 ohms, plus or minus 15% at 68 degrees F. But I suspect this is a type and that it should be approximately .9 ohms or so.

Now keep in mind that .09 ohms is almost no resistance at all. Which is as it should be in the primary side of the coil itself.

The secondary coil is a different animal altogether. SM indicates the resistance is to be 3500 ohms plus or minus 15% at 68 degrees F. The values that you show are on the low side. If what you are reporting is ohms.

Maybe read up some on coil testing. Plenty of stuff on the inner web.

Dan's Motorcycle

[boscoe99]

I would put a spark tester on the motor. If you have a good hot spark all of the resistance mumbo jumbo is irrelevant.

You have two input leads to the coil. One is normally grounded and the other gets its voltage from the cdi. Did you measure between those two points with the coil disconnected from everything? Wire colors would be black and orange.

[rodbolt17]

from blk to orange you will see a very low to 0 ohm reading. that's the primary windings. the secondary ,from the plug wire to blk should be around 21K Ohms. most meters in auto range will read 21K as 2.1 with a small K in the display window. myself, if I did not have a peak reading meter I would use a touch of common sense. I would place the meter on the AC volts scale and test the pulser and charge coil outputs when its running well and see what changes when it starts running bad.

[Jason2tpa]

Did some more testing last night. Used the darkness to see if the spark plugs were firing good. Checked gap of plugs 1st as was surprised to learn both gaps were wider than spec. So i closed both down to the low end of spec (.035). They both were at about .045. Fired engine up with one plug in and other capped and grounded. Good blue sparks jumping gap on both plugs. Then i inspected connections going to coil packs. Replaced 2 that looked suspect. Both of these were the spliced in kill wires from lanyard. I ran engine on flush a while in gear and out at operating temp. No sputter. But of course the real test comes when under load. So i launched boat for a quick run. Ran great. Kept it running entire time bout an hour to make sure no sputtering while hot. Ran at WOT for a minute or so at a time. No sputtering. Im hesitant to feel completely relieved. But maybe it was as simple as closing gap and fixing connections. I'll try voltage testing like you suggested. Curious to see results.

from blk to orange you will see a very low to 0 ohm reading. that's the primary windings. the secondary ,from the plug wire to blk should be around 21K Ohms. most meters in auto range will read 21K as 2.1 with a small K in the display window. myself, if I did not have a peak reading meter I would use a touch of common sense. I would place the meter on the AC volts scale and test the pulser and charge coil outputs when its running well and see what changes when it starts running bad.

[zenoahphobic]

Did some more testing last night. Used the darkness to see if the spark plugs were firing good. Checked gap of plugs 1st as was surprised to learn both gaps were wider than spec. So i closed both down to the low end of spec (.035). They both were at about .045. Fired engine up with one plug in and other capped and grounded. Good blue sparks jumping gap on both plugs. Then i inspected connections going to coil packs. Replaced 2 that looked suspect. Both of these were the spliced in kill wires from lanyard. I ran engine on flush a while in gear and out at operating temp. No sputter. But of course the real test comes when under load. So i launched boat for a quick run. Ran great. Kept it running entire time bout an hour to make sure no sputtering while hot. Ran at WOT for a minute or so at a time. No sputtering. Im hesitant to feel completely relieved. But maybe it was as simple as closing gap and fixing connections. I'll try voltage testing like you suggested. Curious to see results.

People need to be aware that if the spark plug gap is too big, or if the leads are just pulled off the plugs, the high voltage is dissipated within the coil itself often leading to breakdown of the insulation between the windings.