Why Phazer2 Meltdown??

[racerrob6m]

Okay Yammi gurus, here we go, thoughts & opinions as to why did she go
poof!!

Okay, my 3rd ride of the season, but 1st ride for my wife & her 93 Phazer2 which has under 400 miles on fresh pistons that are 2 years old.Sled has 2400 total.

Fresh fuel, same settings as the last 2 seasons, temp was around 28-30 degrees. Did some boondocking of trail 1st for around 3-4 miles. 2-3" fresh snow, good solid base. Then jumped on the trail for a couple miles, got up to 50 or so for a mile, then off the trail, then back on ran for another 2 miles, not hard & then she heard the motor starting to sound "funny, knocking noise, around 40mph, she slowed, motor started to run rough, she stopped & here is what we found after we towed it back & loaded for home & in the shop.

Good compression fan side, only 20-30 pto side. Here are the pics.
Now my ideas are:
A) Left Carb sucked dirt, leaned out...?
B) I noticed that there is some oil in the pan left side, is there a crank seal that could be leaking, sucked air in lieu of oil, leaned out & poof??

And then, the "knocking" noise, did I also lose the crank bearings?? Did not get that far into it yet, am guessing as bad as it "ratteld" when I spun it over with the electric start, probably so. Hmmmmmmmmm.

Thanks, Rob

 

[extreme4max4rules]

u got a broken ring, check the piston for the pin that stops the ring from walking around, either the pin broke off or pin pushed in to the piston to far and that allowed the ring to walk around till it hits a open port and chops up the ring thats not a lean burn down, when u re ringed did u replace the pistons or are they stock. i had the same thing happen to me on my 800 i put new piston and ring on the hole that went down the piston pin pushed in and the ring walked around and chop chop done, how ever my head looks like ur piston lol. make sure ur bottom end is clean or it could take out ur seal. allso make sure nothing is floating around in ur pipe . Al Larson

 

[daman]

Wash looks plenty good on the good side,maybe even a tad rich,the bad
side i don't see any detonation/lean(erosion on the exh. side of the piston) condition on the piston,witch tells me jetting was fine and not the issue.

like said above did you maybe have a failure of a pin and the ring walked?? Hmmmmm..

was the rebuild with OEM parts????

 

[daman]

what kind of R's were your turning??????

 

[PZ 1]

The piston damage was caused by a foreign object in the combustion chamber. It could have broken a ring but it does not appear that the damage was from a ring. It may have been something that entered from the intake. A loose screw or other small piece of metal from somewhere in the system. Or something that entered into the intake of the air box. The intake air is not filtered. Could be a piece from a crank bearing.
Were the pistons changed because of a failure? If so, there may have been a piece of metal still in the crankase from then that finally dislodged and went upstairs.

You will have to take it apart and see if it was a piston ring or retaining pin or search for what it was. The object or parts of it may be stuck in the piston crown or the head.

 

[racerrob6m]

Yep I wondered about all the "dents" in the piston. And, when I carried the pipe out, I noticed a little noise, like a small peice of metal in the pipe.
Hmmmmmmmmm??

The ring thing was on my mind too as the cylinder wall on the exhaust side
is scored with a nice groove (003" to .005" deep) that looks like something
came loose or broke & then scraped up & down along with the hammered
look on the top of the piston.

In regards to the ring & piston job, I did not do it. That was done by someone else, so I cannot speak for what they had all done. Was just told it was done. But now, I will be doing it correctly. Will finish tearing into it & checking the bottom end bearings too tomorrow night I hope.

Also, do not recall, do these jugs have the NiCasil coating like the Exciters of this era did? With that score on the bad one, I probably should just get a new cylinder or not??

Thanks for the input guys.

 

[racerrob6m]

Daman, regarding the rpm's, this sled is set REAL conservative, ya know the "wifes" so clutching is mild etc.etc.

While I was not on it, I do believe that at 40-50mph, it would be turning in the 5500 or so range. I think this one tops out at 6500 or so.

Rob

 

[Mysledblows]

Phazer jugs are iron bore. Just bore to next over and put pistons in. I've got a good head somewhere if you need one. I've also got a good set of slightly used .20 over pistons for a phazer. Let me know if you want to try and make a deal..

 

[racerrob6m]

Thanks guys, will know more tonight when I tear into the jugs & bottom end.
Since I am in there, I am going to do it right.

Ryan, will check what size its at now, might be able to do something here.
Not sure what the stock bore is so will have to check that out.
I do not know what the previous guy did when he said it had new rings, dont know if it was bored over size then or not.

 

[Mysledblows]

STD is 72mm, .20 over is 72.5mm, .40 over is 73mm

 

[racerrob6m]

Hey thanks Ryan, will know more tonight when I finish teraing it down.

Following is a great link to piston diagnostics, with thanks to
SamuelJackson over at the Vmax4 site,

http://www.pwab.org/PISTONDIAGNOSTICGUIDE.htm

Pretty darn interesting & good to have for any sled wrench to have in his bag of tools!! I printed it for my collection of info.

 

[racerrob6m]

Started tear down

Now what I did find in the tear down is the rod bearing for this piston is completely gone, so as someone posted earlier, it looks to be a rod bearing failure & some of the needle bearings went through the that cylinder.
I am attaching pics of the shrapnel I shook out of the Y pipe & pics of the piston, rod & crank case assy. the sharpnel in the Y pipe must be what I also heard in the pipe itself when I removed it last night. It looks alot like the dents in the piston huh.

You will note the discoloration on the rod end & up the rod. It got real hot when the bearings failed. Do not know how bad the crank is as I have not split the case yet. Hopefully, the crank is salvageable. There is roughly 1/4"-3/8" play in the rod to crank shaft connection right now. The cylinder walls actually dont look too bad. Will have to hone it out.

Mic'd the cylinder diameter to see what size was in there. Mic'd at 72.45 on the top side & 72.50mm on the bottom, checked it a few times hmmm??
So it was bored over once so will probably have to go to the next size.

Now, why did the rod bearing fail, 2400 mile sled, sucking air somewhere ??

Rob

 

[PZ 1]

The most likely cause for the bearing going bad would be rust. It happens when a sled sits for a long time, from moisture in the air. The bearing rollers cannot tolerate the pits made by rust.
The crank can be rebuilt at a shop that does 2 stroke crank work.

You are very lucky that the rod did not let loose and take out the crankcase. It would not have taken too many more revolutions.
There may be some grooves in the case, but it is okay unless it has cracked or has spread at the parting line.

You may want to see if you can find a used Phazer engine or a whole parts sled.

.