Here is a another quick question.
What gasket kit did you use o. Your 82 mm piston.
Thank you for ansAwering all questions.

When you do pull the head measure the ID of your head gasket.

Adnoh,

Are you thinking he has a detonation issue because the head gasket is protruding into the squish band which will cause the piece of head gasket to constantly glow red acting as an ignition source which will cause pre-ignition?

Rand

I used a Cometic Top End Gasket kit - 82mm. Will take measurements and post along with pics. Hope to get done today/tomorrow.

Pulled the lid off the cylinder and looky-here - a new breather hole in the piston!



Pretty sure that wasn't there when i put it in. ;)
(CO, so much for slapping it back together on the cheap with this piston!)
The cylinder walls look good and doesn't look like there was any leaks around the gasket on top





Well the good news is a light hone and a new piston, rings and gasket kit and she can go back together but what the he11 is going on here?
Here is my take: it probably wasn't a gas issue, there were no air leaks and the cylinder and head have not been modified. Timing? Intermittent CDI (Capacitor Discharge Ignition) issues? Anybody got anything else?
Also, FYI, I did replace the coil with a new one from E-Bay same time as most recent rebuild.

Also in the good news column, I don't want to get rid of it anymore. I really do enjoy the wrenching part, it's wrenching on the same thing over and over that really sucks.

Just slap some JB weld on it, then good as new
make sure there is no aluminum in the bottom, a little on the bearings will make them skid like a clay skate board wheel hitting anything on the sidewalk, anyone remember those

Well there's your problem .
That's one hundred percent fuel detonation in my opinion. Proof you are running crap fuel.

I did consider the JB weld :) that stuff is awesome!

Any ideas on rinsing the insides to remove any remnants of aluminum without splitting the halves? Any reason not to use diesel fuel? I did that a long time ago on my old GTO when I broke a lifter. Any reason it won't work here?

On a positive note here -- based on what I see in the pics, that cylinder looks in very good condition. Run a hone up and down a couple of times and put in a new piston and rings. Like Kuma said make sure no bits of aluminum in the bottom. Good to go -------- with GOOD FUEL.

I have done that and with compressed air. The problem is that you can't guarantee there are no bits still left in there. You will have to be the judge on that. Another issue is that you can't really get a good look at the rod bearing to see if anything is in there. That's a really small hole so probably most went out the exhaust before it finally poked through. Splitting the cases is the best option but if you are trying to see if this Engine lives then you could take the DF route. I have gotten away with it before. You will have to be the judge when you pull the cylinder and look down the hole.

Everyone of these fuel related except the last two.

Not every hole in a piston is due to bad fuel.

That will also happen if you don't get your premix right and or she's running too lean on wide open throttle.

The first piston I ever burned up was exactly like this scenario and it was from running too lean and doing high speed passes down Pismo beach on my FL250. The one thing I didn't take into consideration was an excessive amount of humidity due to riding directly on the beach next to the water.

Rand

Feel pretty confident the mix was good - running Motul at 32:1

Here is the connecting rod bearing



There is definitely some metal fragments there and saw a couple of small nuggets in the area right under where the cylinder sits. I really don't want to take short cuts but would love to be able to rinse the case with diesel and compressed air. Is the general consensus I should split the cases and go through the lower end in a more formal fashion?

If you have the time and the will I would split it and clean. It also gives you a chance to get a good close look at the rod bearing for any contamination. Your call.
One other thing I thought of, something really smells here. Everyone else with a Pilot does not seem to have this many issues. It's the FL350 that has all the problems. So my question: Could it be that Turner pipe ?? A lot of a two stroke is the pipe. I wonder if this thing is not as advertised ?? Ask the original owner who changed the pipe and carb if it was running good until this change was made. When did he pop the first Engine ??

Edit: I am sure everyone is sick of all my posting but I am temporary unemployed and all I do is play in the shop, walk my brothers dogs and yap yap yap on this site. This site is a social safety net for me right now. Thanks for listening.

My money is on carb issues. Just my opinion.

carb has been completely disassembled and cleaned (multiple times!) and soaked in ultrasonic cleaner. would appreciate if you can detail any thoughts here. it would have to be something intermittent that is causing it to lean out. it is a pretty simple piece of hardware and it seems if the slide moves correctly and all airways are clean, it should work.

he popped it right after he put the pipe, carb and clutch on. I do have the stock exhaust too.
oh, and keep on with the yap yap yap, the help and feedback is always welcome!

good morning Rand.
Yea thinking it may have been, after looking at the piston and the fact it was cosmetic. do not think so.
Im going to go back through the whole thing this morning compiling info. Getting all the correct facts in order will help .

I can say I have never seen a centered blow hole on a water cooled pilot piston with out a dramatic change in something.

Mean while how about a few pics of the plug that was in it. then after you document the plug , type ,# and all angle pics. Cut the base off the plug and then take new pics. One shot deal so get your pics right before hacking.

The way the piston and cylinder look it leaned out on top end during a sustained WOT (Wide Open Throttle) run. No if ands about it. In no way was that a mid range lean. Remember every one this is a wiesco piston.

I would also like to confirm that yes it was a PT pipe and Stock silencer.

I would also like to confirm CR not static compression. You can simply get me the number either in English (Being humorous)or mm. Take your caliper and set it on the base (tail) on top of the cylinder and run the tail down until it reaches the top of the exhaust port. please provide this number. I can enter into my data spread sheet. I used my data for your Engine set up using known numbers and it came out ok so I need this to confirm.

Once data is collected in order the info will be processed in this faction with a cause and effect hypothesis.
I ask you be penitence with any changes you make to this Engine until all question can be answered. Other wise order new parts and stop there. Then we all can use our experiences to help solve in a logical manor.

Mean while lets keep up the good work on the Q&A. its all reverent.

Thank you Adnoh

forgot. Please add pic of under side of piston.

I stated I feel that it was a WOT (Wide Open Throttle) sustained run. I offer this as why I concluded this.
First the piston pic at TDC (Top Dead Center). I arrowed the this up for explanation:

#1 The hole was right under the plug. The hole is also conical. This leads to the blow hole.
#2 If you look at the area around the outside of the piston I arrowed It shows a fairly whale
(no pun intended to blow hole) laid out heat signature. He said whale, ha ha.
#3 This shows that the excessive load was quick and thermal expansion was taking place at a high rate.
#4 If you continue to follow this white looking band around the pistons crown edge as it narrows you will see
that it is continues in nature. I like this it is a distinct pattern that proves the rings were doing there job in
way of heat transfer to the cylinder wall and transfer to the coolant. I can rule out poor machining and break in.

I post this for answers. After reading above statement. guesses to what these are and why they look the way they do.

After all this is a learning and informational site.

These tell a story.

I have had 2 pistons that burned a hole in the center like yours and another that a buddy sold me because he burned a hole in the piston too.

1)I shredded a belt and locked up the Engine by getting bound up in the power bloc clutch on a WOT (Wide Open Throttle) run.
2)I did not tighten the spark plug tight enough and it came loose, again on a WOT (Wide Open Throttle) run.
3)My buddy took off the air box and ran a cheap pep boys hi-flow air filter without changing jetting, again at WOT (Wide Open Throttle).

Hopefully this info may help:)

I agree with adnoh, a dramatic event had to happen in a very short time to burn a hole in the piston. I have ran an Engine that had piston to cylinder wall clearance issues and never burned a hole in the piston.

Here is another marked up piston pic.

This shows the way the engines intake/ savaging system was preforming.
I kind of like what I see here. It tells me some port modification need to take place.

So as you look at this picture try to take in a geometric shape, orientation.

Please feel free to goggle this comment words if need be it will help.

This also is an indicator of quick heat at high rpm.

This also proves additional port work is required for such rpm.

Once we look closer at the head pic this will fall in line with I'm saying.
If you your not sure or saying I do not get try this. Look at the last two lines towards the exhaust port. Now tilt you head to the left this will create an obtuse angle of degrees offset from center line of the exhaust port or a vector angle reference.

This angle is bad very bad and tells one that some port angle and duration changes are in order.

Now after looking at this pic go back the previous one where I ask for comment. check out the relation ship of angles area and port openings.

Pilot Bird Brings up an very good if not great point. Heat dissipation or exchange through the plug is very important.

I pulled these off the web for reference. A loose spark plug can lead to an over heated tip and pre-ignition. Now you can why I wanted close up pics of plug.

Thanks Pilot Bird. Back on track for me.

Back the question pic. The two lines are the rings end gaps. Most of you already knew that. The import key to distinguish these from the others lines they left on the cylinder. The ring end gaps will leave these non contact marks in a high heat transfer from the rings to the cylinder and not to be confused with scuffing.