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I got one of those max but I couldn't work out how it was supposed to work

You can get a $10. tester but not sure how well they will work on a mower Norm.

Thanks Max,
The PET 4000 seems to be the go but it is worth more than all the mowers I am trying to fix Might be better to send them to scrap and clean this place up

I thought I'd just list the differences.

What Each Tool Does
PET‑4000

A basic spark-gap tester that checks whether a coil can produce a spark under realistic conditions (cranking or running).

Uses an adjustable gap (about 14–29 kV) to stress-test coil output.

Simple, quick “spark/no‑spark under load” tool — ideal for spotting weak or dead coils on small engines.

GTC505

A full ignition analyzer that measures spark voltage, burn time, dwell, RPM, and can show waveforms.

Diagnoses misfires, weak coils, or inconsistent ignition across cylinders.

Works with distributor, Distributorless Ignition System, and coil‑on‑plug systems — suited for professional diagnostics and tuning.

When to Use Each
Situation / Need Better Tool
Quick go/no‑go test on small engines PET‑4000
Suspected weak or intermittent spark GTC505
Multi‑cylinder or coil‑on‑plug systems GTC505
Simple “is there spark?” budget check PET‑4000
Detailed diagnostics or tuning GTC505
Key Trade‑offs
PET‑4000: Simple, cheap, but only shows “spark or not.” No data on spark quality or timing.

GTC505: Powerful and precise but more complex and expensive; may be overkill for basic engine checks.

Quick Summary
PET‑4000: Best for quick, stress‑under‑load spark checks on small engines.

GTC505: Best for in‑depth ignition analysis, especially on multi‑cylinder or electronic systems.

For ordinary lawn‑mower or generator diagnostics — use the PET‑4000.

For tricky misfires, tuning, or professional shop work — choose the GTC505.

Cheers
Max.

You could get one of these pictured and adjust spark gap while engine is running.

That is an idea Max, idler pulley would have to be mounter inside under the cover plate but yes it is doable

I wonder if there is an easier way Norm to mount the motor solid on the base and just fit in a tensioner pulley on the slack
side of the V belt ,fit an adjustable pulley to keep the belt tight or a spring loaded pulley, the wreckers are just under $20. for
an IDLER PULLEY.

Also a new idler pulley is cheap ..

Hi Max,
It is just a bit of 100mm heavy pipe, welded a blank end on it, put it in the lathe and bored the center out, pretty simple when I finally worked it out.
As for fitting the PT's on the early bases I have fitted one using a modified F/C sliding plate. Bit of messing around but I just have to find my drawings of how I made it . The problem stems from the F/C using the plate as their slider but the PT bases use the base as the slider. I have a few of the 4 stroke slider plates and I have looked at them before but they didn't lend themselves to be adapted for some reason

Where did you get the seals? They appear to a wacky size! 0.875 x 1.560
I'm in Melbourne

Hi Norm,

That looks much better now ,you have a lot of the weight on the outer ring ,instead of in the centre ,this allows for a lighter weight
but it has more effect to keep the motor turning.

I can't tell if you've adapted that from something else or machined it to suit.


I would have thought getting a PT to fit a full crank plate would be simple if you use the PT off a Tornado base with a longer crank and just
use an adaptor plate ,Victa had adaptor plates when putting a full crank on a 4 stroke base (the sixties self propelled mowers) I've used these
adaptor plates and turned the plate upside down to fit a 4 stroke motor on a 2 stroke base ,the Victa plates are difficult to come by but you can use most of the Villiers adaptor plates from the sixties and seventies or just make something.

Cheers
Max.

Hi Colin,
I'm surprised you got the wrong chain, I know you have been dealing with chains for a very long time (Only joking)

Well see if this one is closer.

#40 Roller Chain 1/2" x 5/16" 43 drive links. The other chain was probably a 3/16" version for the non differential models.

Stockman 231901

or

Stockman 231901 chain

IPL Manual Download

22-25I3-25E94-25K94-25H94-25C95-25K95-25K96.pdf

Take with a grain of salt as I am a few skips and a hop from the there.

I'm a little bit late to this party!
Here is a picture of my magneto.( I hope it loads!)

Runs clockwise looking at the mag. My coil is in the correct position and is producing a nice spark.

I built a mini-bike in 1967 using one of these motors, so I have a nostalgic soft spot for them.
I recently acquired one and am in the process of getting it running.

I need a Carby and the bits that attach to the magneto to wind the rope on to pull start it.

G'day leslloyd,

Please don't contemplate deleting your post, actually, I don't think you can... although I could be wrong on that admission .

Having said that, I'm sure that there will be somebody here that will be able to assist you with your predicament...

Regards,

mice_elf

Turns out it was the incorrect one.to narrow so back it went.No help here,can i delete ?

Now that neon tester shown it good to indicate a spark is present just won't show the strength of the spark. This is where a spark gap type is needed. I several Kawasaki that showed a spark but the overall strength so weak that it couldn't fire the plugs under the compression load.

Yes your Dad took hit instead of the calf. That is the strange thing about electricity. It is whatever farthermost away seems to always takes the hit first on power surges. In your Dad's case whatever closest to ground potential.

I once had a laptop modem to take a hit even it had to go thru my computer first when there was a lightning five away at the phone company's hub building. I was just checking after hours for the next day service calls and to upload daily reports. Good thing I had copy of the company's software on the home computer as it took a week to get it thru to my area's manager that I needed a new modem.

This is my latest idea and so far no sign of any kickback and this is not too time consuming to make Kinda makes me think PT's on 24 isn't such a bad idea. What I now have to work out is how to mount PT's on the earlier F/C 24 inch bases. Happy for anybodys thoughts

Bit like my old man when we lived on the farm and a calf kept getting through the fence, old man picked it up in his arms and shoved it nose onto the wire. Problem was the calf didn't have its feet on the ground but the old man did. Mum couldn't stop laughing

So she done got wise to your tricks.

Usually the young trusting ones that fall for this trick.

It sorta like holding onto an electric fence wire and getting someone to touch you. They only fall for it once. That was a fun thing when I was a kid. Of course I had on rubber boots.
.

Or the old charged up condenser trick that is pulled on new mechanics.

Had request to look at a non-starting, petrol-leaking generator at a nearby property, Chinesium rubbish with stuck needle valve and muffler filled by mud wasps, got it started and then chatting about old machinery and they had a couple of defunct mowers sitting out in the open some years, since replaced by a ride-on.

Two Victa Craftsmans, one green Model #BC082 AA90 which I brought home, the other orange which will be picked up next time I'm going past. Said to be seized but turned over OK and started up with a few mls of 2 stroke down the plug hole. Cleaned out the grotty tank and it's a good runner although revving much higher than I like.

I have been trying to avoid acquiring any more 2 strokes but, hey, how can you say no when they just jump into the back of your car?