Fuel, fire and compression. and still nothing

[Hammermechanicman]

In

BTW, do plugs throw a thicker spark at lower RPM's? Say like when one is being cranked?

We sometimes think a 10,000 rpm 2 stroke engine will have a hard time sparking that fast but in reality it is a non issue. Cranking speed or 14000+ rpm the magneto puts out the same energy. Consider my 1966 396cid chevy with a standard 3 ohm coil and points. Turning at 6000 rpm the distributor is turning 3000 rpm and opening the points 8 times per rev. 3000 x 8 = 24000 spark pulses per minute. Above 6000 rpm you needed a magneto or a dual point distributor. The operating speeds of small engines from cranking speed to 15000 rpm is insignifigant to a magneto ignition. Some chainsaws have speed limited coils. At somewhere around 12000rpm the saw starts "blubbering" and folks think the coil can't keep up when in reality it is designed that way.

 

[bertsmobile1]

The faster a magneto spins the higher the voltage , the faster the votage rises & more powerfull the spark
IT is the exact opposite to a battery & coil .
Think about adjusting the speed of a generator, too slow & you are undervoltage & too fast and you go over voltage .

The term coil saturation is used to describe the time it takes for a coil to become fully charged and it is a set time
The faster the magneto is spinning the less time is available to do this , so the coils on small 2 strokes are wound to be able to be fully saturated at whatever the operating speed of the engine is .

 

[StarTech]

Don't get trapped in the illusion. Thinking somewhat outside the illusion helps.

The service manual will provide you a hint of what may be bad....Get a copy of it or someone here that has it should read it and then post the info. Hint: It is in section 7. Bert's and Scrubcadet thinking is on track if this is the cause. Won't be the first time I have seen it.

Also technical bulletin 25.2005 needs to be referenced when comes to the flywheel. The IPL only references one flywheel and ignition coil setup but does note the TB.

Something I haven't needed but I should get it anyways.

 

[PTmowerMech]

Don't get trapped in the illusion. Thinking somewhat outside the illusion helps.

The service manual will provide you a hint of what may be bad....Get a copy of it or someone here that has it should read it and then post the info. Hint: It is in section 7. Bert's and Scrubcadet thinking is on track if this is the cause. Won't be the first time I have seen it.

Also technical bulletin 25.2005 needs to be referenced when comes to the flywheel. The IPL only references one flywheel and ignition coil setup but does note the TB.

Something I haven't needed but I should get it anyways.

The part numbers on the flywheels matched. The engine finally turned over, as I stated before. And after the other flywheel was installed. But not immediately after changing the flywheel. There was still a LOT of pulling and spraying (carb cleaner) before it finally hit.

So, the finally diagnosis was that it was haunted. And I finally pulled on it enough times that the ghost just gave up.


If this small engine stuff doesn't work out, I'm going to be a ghost buster. ?

 

[PTmowerMech]

Well this darn thing is making a fool out of me, still. Got the new carb on and it fired right up. But it just wouldn't adjust right. WOT, while turning the screw would get it spot on. But hold it there (WOT) for about 10 seconds and the tone would change. Let off the trigger and it dies. Just after idling fine for about 5 minutes.
Then wouldn't crank again. Or would crank.

Just fires off when it wants to. Hard to tell by the spark tester if it's losing spark when shutting down. It looks like it's not a spark problem.

Note to tells, don't let your stomach touch the spark tester at WOT. OUCH!!!!!!!

 

[Fish]

I would say that you may have a blown seal, or some other air leak.
So a leakdown test would be something to think about.

 

[Hammermechanicman]

Yeah, you need to check the crankcase bolts for being loose and if they are tight do a pressure and vacum test. Also check the impulse hole to the carb is clear.