FS55RC, extensive t/shooting & repairs done. Dang it...still won't start. Long read, apologies.

[Martepm]

Howdy all.
Been looking for insight on above issue for a long time & on numerous sites....to no avail. There is a hidden problem somewhere here I'm missing.
Seen some scholars respond here so thought to make one more attempt to request some input to figure out what I am missing.
This is a doozie for sure & there isn't much left!

To give some background, I have just closed my industrial petroleum maintenance & compliance testing company. Retiring after 26 years. (Thank God!)
So yes, I'm a t/shooter & very mechanically incline, in the electronic's field also.
Since I have time now, thought to repair some weed eaters & blowers friends have given me over the years. Some I repaired & gave back. Others were dumped off & they bought new ones.
I like to tinker in the garage in my spare time to keep my mind sharp. Thus, I'm their dumping place.

To the point & 1st project...my own 06' FS55RC with easy2start. By calculations about 200-300 hr's of use at/for home in the 16 yr's I've had it. Gradually over the years it got harder to start & keep running.
Compression is at 130 lbs. The following have been replaced so far; fuel & air filters, fuel line, carb, spark plug, coil & flywheel.

*Spark seemed weak so replaced coil,... no joy.
*New complete fuel system. Bulb filled up quickly & looked like it was ready to fire up,... no joy.
*Had spark but wondered about timing. Sure enough flywheel key got sheared off. Installed new flywheel with green loctite to prevent future movement & let it dry for a week. Used business card to set coil air gap, making sure both induction points didn't move,... no joy.
*Removed muffler & removed spark arrestor screen even though it was clean,...no joy. Cylinder walls & piston looked as good as one would expect with little use. No scoring, hardly any wear.
*Today installed new starter rope & spring (wore it out in this process) & tried that, no joy.

Took starter off & got smarter..used 1/2 elect drill to turn motor over (clockwise spin) to check spark, still looked good. Several times tried spraying starter fluid in carb, then in cylinder & spin motor with drill...nothing. Spark plug seemed dry to me. Tried same with 50:1 Stihl oil&gas, nothing again and even noticed vapor being expelled out exhaust without a hint of attempting to fire up. Plug again seemed dry to me. Put a sample of both fuels on bench & tried a lighter. Both lit with ease & burned for about 20 sec's. Previously sprayed head with starter fluid & placed spark plug on it, it lit & burned off.
Just to check compression again as one might ask....130 lbs. Added oil, rotated motor in tilted circular motion to cover walls/rings then spun with elect motor to coat the rings & walls. Attached gauge after that and now have 170 Lbs.

So there you go. By all right's it should have at least fired. Still...nothing, not even a hint of ignition. I'm completely dumbfounded now.
From my many years of t/shooting...in general,...one thing is clear....all the improvements I've made have had no effect whatsoever.
Thus, there is another unknown issue that hasn't been addressed.
Just now learning about crankcase pressure. Perhaps?...but it should have fired after spraying in carb or cylinder.....correct?

Noticed, spark plug seemed dry throughout these test's. Yet it had the ability to ignite starter fluid once outside the cylinder. (WTH?)
Checking TDC, highest piston point...was between both magnets on the flywheel, on the coil side of steel induction frame.

Wanted to sell this & others for added income. At this point I'm about even for what I can sell it for, maybe $125.
Hate to throw it in garbage after spending that amount to get it running again, if you know what I mean.
Hoping one of you scholars can step in to help recover my expense so at least I'll break even & learn from my mistakes.

Sorry for long post but being as specific and factual as possible,....as this is not your normal everyday issue in the many, many "won't start" post's I've read.
My thanks in advance.
Mart

 

[Rivets]

The one thing you have not checking are the crankshaft seals. At that age they are probably dried out and not sealing the crankcase. This would result in the air/fuel mixture being pushed out of the crankcase around the seals and not into the cylinder. This is the only thing I can see which you have not considered.

 

[Martepm]

Thanks Rivets, just learning about that now.
Is there some test to determine their integrity? Haven't gotten that far yet.

 

[Rivets]

Just like any oil seal, you can tell how dry they are by poking them with a screwdriver. Rubber should be flexible. At that age and the amount of $$$ you’ve stuck into the unit I’d probably just replace both of them

 

[StarTech]

Also check flywheel key for shearing.

 

[Martepm]

Flywheel key shearing was addressed & found at fault. Flywheel replaced.

 

[sgkent]

did you replace the spark plug? Compression changes the voltage needed to fire so a carbon track that might jump under compression might be fine outside the cylinder. Personally at this point I would pull the plug, squirt a half teaspoon of fuel into the cylinder thru the plug hole and try again.

 

[Martepm]

Yup, been there, done that as mentioned in original post.
With all due respect in helping....way past that point in t/shooting. A far reaching & more deeper issue is at hand.
So you might understand, read about 8-14 hr's of post's on this subject from multiple sites.
I'm far beyond the "normal" everyday t/shooting.
Something else is at hand that hasn't been covered.
But thx for input.

 

[bertsmobile1]

Actually it has probably sheared again as it is a taper and putting anything, including loctite on a taper prevents it locking tight
The other biggie is the transfer ports
As rivets has already mentioned the crankcase is pressuriised by the descending piston and when the hole in the side of the piston aligns with the hole in the cylinder wall the charge in the crankcase is forced into the combustion chamber .
These often get damaged
Now historically we do not want to know what you have done
When we need is for you to do what we ask now and give us the results of the NEW test
SO a couple of things , in no particular order
1) as already requested do a new fuel down the plug hole test
2) remove the flywheel , check the timing key and clean both side surgically clean
Bring the piston to TDC and mark the side of the flywheel where it enters the coil legs with a white paint pen .
4) strobe the flywheel with the plug laying on the side of the block and look at where the index line you just made is
It should be about 30 deg away from the coil leg when the strobe flashes .
This is a rough test to verify that the flywheel is the correct one for your engine
5) Pull the carb off the engine but leave the fuel lines attached
Turn it sideways & blow air through it to simulate normal running
High volume low pressure is best
If the carb is working properly you should get a strong flow of atomised fuel coming out of the engine end
Do this with a tank chockers full then 2/3 empty .
6) if you have a propane torch, adjust to a fine flame and play it across the plug hole.
You should see the air:fuel ignite as it comes out of the cylinder when you crank it with your drill .
An old diesel engine glow plug works well for this
7) And of course the old hot plug is also worth a try
Heat one up with an oxy torch using a very lean flame to burn off the residue that you can not see that may have deposited on the plug when the engine did not fire.
As you probably already know modern fuels ( which are not petrol ) can be very conductive at combustion pressures .
Install the plug wile too hot to hold in bare hands & see if that will fire .

And so we know exactly where we stand
I ask people to do tests that all of the techs here will understand the reasoning behind
If you do them & respond then I ( or others ) will take things further based on these results alone ( what was done in the past is meaningless ) .
If you can't be bothered to either do them or respond with the results then I can't be bothered devoting any more time to your problem .

The order is not important , however it best suits you is fine
Doing all of them is important

Lots of new parts sourced from evilpay / ammozone are actually rejected defective parts bought as scrap metal then sold to cheapskates on line .

 

[Martepm]

Nicely done Bert. Appriciated. Exactly what I was hoping to find here.
I printed your instructions for the work bench & will go thru them one by one.
I too had suspicions about the replacement flywheel but found myself trying to convince my myself that couldn't be the problem.

This has become a personal challenge & a driving force to figure out what is happening.
I will be back to report findings once all are completed.
My thanks for all the input.