Getting funny readings when doing pin point tests.

Starts up great, idles all day. Runs great when cold. When warm no power, acts like a rev limiter. RPMs surge, like someone killed the key and turned it back on. Used to believe it was vapor locking, but this last trip it started acting up way to fast to be vapor lock.
I did try running with gas cap off or loose.

Originally thought it was fuel. Been through the Carb 3 or 4 times now with multiple runs through an untra sonic cleaner. Confident that is not the problem. It is the OEM carb. Fuel petcock was oxidized badly, replaced it. Fuel comes out of the tank plenty fast. After each carb rebuild it has never gotten better or been different in any way.

The last time I rode it hard I had to keep the rpms down and it was fine. This time I rode it hard and it won't pull it's own weight after it warms up.

I need to recheck the valve lash, but it doesn't have 10 hours on it since I checked it last. This is getting worse over time. Not really run time either.

So I moved on to electrical. Started checking it out.

Started the atv up and let it warm up. Got it as hot as I thought I could. Shut off and started resistance testing.

Ignition coil. Spec Primary 1.8-2.8 ohms I get 3.6
Secondary spec 10-16 K ohms I get 18.6 K
Ordered a replacement coil, it came and it measures worse than the one that is in there. So have not installed.

Pickup coil spec 390-590 ohms I get 597 ohms.

Stator coil spec. 0-.7 ohms. I get .9 ohms.

Battery voltage, not running 11.95
Running 13.45, it holds 13.45 with lights on, revving engine. Stays right there. No change.

Spark plug is new, again.

CDI box, This was really confusing. I get resistance where I should, and not where I shouldn't. BUT I should be reading K ohms or less and I read Meg ohms for almost everything. To me it shouldn't be running it is so far out of spec.

This thing has been babied. It still looks new, has original tires on it yet, and with decent tread. It has never sat outside even one night. No deep water runs, or mud runs. It used to run circles around my friends honda 300s. Now it is a joke.

It is 26 years old so I said fine. I ordered, igniton coil, regulator, cdi box, spark plug. Figure I will swap pieces one at a time. But I hate throwing parts at something since often the replacement parts are worse than the original.

Is my stator far enough out of spec? Shouldn't matter should it? Since my charging voltage is good?

Kind of sitting here thinking I need to put a timing light on and just watch it when running to see if spark stops?
Maybe put a test light on the primary side of coil see if it keeps pulsing, or if the constant 12v goes away at all?

Any thoughts appreciated.

 

I guess you already know, but it is not CDI ignition. Kawasaki used the same set up as cars had back in the 1980s, which imitate the old contact breaker (negative make and break) system electronically. When I started reading your question, I instantly thought it will be overcharging (voltage regulator) but I see you have checked it and found it right. May be worth checking when the fault is on. In fact with these "only comes on when hot" faults they only show when the fault is on. About 18 months ago I got an Ozark which would die when hot. Ran fine for 5 to 10 min, then just cut and wouldn't start again until cold. I suspected the pulse coil, but it tested right. Even sent the stator unit to a rewind specialist to be tested and they said it was OK. Anyway, eventually the fault came on when I was able to test it and the pulse did test as wrong. Only reason I hadn't just fitted a new coil was Suzuki would only sell the whole stator. Anyway checked eBay and aftermarket pulse coils were available for £20, fitted one and got an instant cure.

 

Last night I pulled the baffle out of the muffler. I thought it was a spark arrestor but nope, just a baffle. Started it up and blew a bunch of chunks out. Wasn't plugged but worth checking I suppose.

I am headed out of town for a couple days and I don't have parts yet anyway. But when I get back to it I think my plan is to hook up a timing light to watch spark. While also putting a voltmeter on the positive side of the coil, and maybe even a test light on the negative side of the coil.

Then if I can get it to act up then it should point me in the right direction, or at least the next direction pretty fast.

 

I was able to play a little. Coil does not ever lose voltage.

But timing light tells me I do lose spark.

Tried a test light on negative side of coil but pulses too fast I can't tell if it is losing signal or not.

On a brighter note my regulator/rectifier showed up.
Voltage before was 13.4v. Voltage now is 14.2. So I think that is a win but still not running better.

When my ignitor box shows up I will try that next.

So current possibilities are pickup coil, cdi/igniter box, or coil.

 

Just to Update, I installed a new ignition/cdi box from amr racing. no change.

Installed the new ignition coil. Fixed.

Now I just hope my out of spec ignition coil doesn't destroy the ignitor box. LOL.

Running hard, it is pulling steep climbs in 2nd and 3rd gear as good as it ever has.

But it does seem to run out of fuel on long hard, wide open runs. Of course this doesn't happen often, but I am wondering about adding a fuel pump or modding the needle in the carb or something to allow more flow.
It comes out of the tank plenty fast, With the bowl off the carb it is obvious the restriction is in the needle.

 

As I wrote above, it is a 12v coil on the 300, as long as you use a 12v coil it should be OK. CDI coils are a totally different thing, I would not use one of those on the 300. I would be surprised if coils for the 300 are not available, cheap on eBay, anyway.