Need help on busted piston cause

[Flyer]

I tore down a friends engine and am preparing to rebuild it.  The engine is an 03 88b that had 95" jugs and SE 10:5 cast pistons as well as a SE cam plate hyd tensioner upgrade.  One of the pistons came completely apart destroying the front cylinder and bending the end of the rod.  So I am examining useable parts saving the cases because it is an anniversary model.  The 95 cylinders and pistons had about 5,000 miles on them when the piston pin pulled out of the piston.  So my examination left me puzzled as the surviving piston pin was blued from overheating and the inside of the piston did not look like it even had oil on it.  The front piston pin from the cylinder that failed is stuck in the rod.  So it appears there was not enough oil getting up to the piston pin.  I did apply air to the surviving oiler and it was not plugged.  So shouldn't there be enough oil flinging around inside from the crank rod bearing surplus oil and the piston oiler jets?  I did measure the lifter bores and within spec under .002.  Any suggestions would be appreciated as I am uncomfortable just putting it back together without some understanding.

[Hybredhog]

  How much oil was left in the sump? In theory, even with splash oil from the spinning flywheels, should be enough to lube the wrist pins, but might seize piston. Does rear have seizer marks. Without seeing it myself, I'd be leaning to no oil supply at all, and lifters usually clatter first iif that's the case.  Bottom line is cases have to come apart.

[Matt C]

Sounds like detonation. That destroys more "Potty mouth" anything

[rigidthumper]

Look at the underside of the piston- bet it's black, (if so,  detonation is indeed the cause).  HD Hi comp cast pistons didn't tolerate detonation well, cracking/breaking under stress wasn't uncommon.

[Flyer]

Thanks, guys.  There was plenty of oil, although kind of bad looking IMO.  The bottom of the surviving piston was completely shiny, and did not even seem to be coated with any oil?  However on the surviving piston the piston pin actually turned blue???  So to me it looked like no oil at all. 

I did split the cases and of course the crank and all bearings are being replaced.  I am just trying to understand why the unusual apparent lack of oil that possibly caused the wrist pin to seize and destroy the front piston.

[dsvracer]

i would check the piston oilers to see if they are working properly.

[dakota224]

How`s the oil pump look? How much run-out was there? I bet the problem starts there.

[CW#]

 

Sounds like detonation. That destroys more "Potty mouth" anything

[2006FXDCI]

i would check the piston oilers to see if they are working properly.

What is the best way to check them ?

[prodrag1320]

i would check the piston oilers to see if they are working properly.

What is the best way to check them ?

Just blow air thru them.i made a test fixture with a regulator,

[rbabos]

i would check the piston oilers to see if they are working properly.

What is the best way to check them ?

Just use a rubber tipped blow gun. Back the air regulator off and increase pressure until you hear the ball vibrating and allowing air to pass through. This shows the pop off pressure +/-. I think it was around 12-15 ish.
Ron

[rbabos]

Technically they are cooling jets not oilers although the excess ends up in the underside of the piston and cyl walls. The piston will survive from the oil from crank fling and oil travelling up the con rods from the oil to the big end bearings without piston squirts.  Now if oil was starved to the crank pin will take out the pistons but the rod bearings will be toast too.
Ron

[2006FXDCI]

Thanks for the info Kirby and Ron 

[Flyer]

I really appreciate all of the input.  I am not an expert, just a learner.  Just haven't seen blued wrist pins before.

When the piston broke the rider was going 80 and pulled the clutch immediately.  However there was just enough rotation to twist the front rod.  So the crank is junk.  Interestingly enough the oil pump looks unscarred and all the bearings roll but they will still be replaced SAOP.  Basically the only thing going forward is the SE cam plate and oil pump and rockers and the crank cases.

I did check the piston oiler however not with regulated air pressure.  I will do that.  Thanks for the tip.  I will also check the rod bearings for looseness and see if the destroyed piston top is in that baggie of parts they gave me to see what it looked like.

The surviving rear piston had no signs of detonation and was completely shiny and clean like new even on the underside.  It also had a blued wrist pin.  Initially I had just assumed that it was understandable for a cast piston to break, but then looking at the surviving piston it showed a lack of cooling.  Could a tune be so far off that the piston would overheat enough to turn the pin blue leading up to the piston failure?  I think I will dig through the parts bag they gave me of broken parts to see if the piston top is still there. Also the tune was a canned map that matched the engine precisely with a PC3.

So moving forward - replacement crank, forged pistons, new cylinders, all bearing SAOP, different set of heads.  We will see if we can reuse the SE Oil pump and Cam Plate and rockers.  Just trying to avoid whatever caused the failure, and when you don't know for sure it just leaves you a little uneasy.  We all love that mystery don't we?

Thanks to all. 

[rbabos]

I really appreciate all of the input.  I am not an expert, just a learner.  Just haven't seen blued wrist pins before.

When the piston broke the rider was going 80 and pulled the clutch immediately.  However there was just enough rotation to twist the front rod.  So the crank is junk.  Interestingly enough the oil pump looks unscarred and all the bearings roll but they will still be replaced SAOP.  Basically the only thing going forward is the SE cam plate and oil pump and rockers and the crank cases.

I did check the piston oiler however not with regulated air pressure.  I will do that.  Thanks for the tip.  I will also check the rod bearings for looseness and see if the destroyed piston top is in that baggie of parts they gave me to see what it looked like.

The surviving rear piston had no signs of detonation and was completely shiny and clean like new even on the underside.  It also had a blued wrist pin.  Initially I had just assumed that it was understandable for a cast piston to break, but then looking at the surviving piston it showed a lack of cooling.  Could a tune be so far off that the piston would overheat enough to turn the pin blue leading up to the piston failure?  I think I will dig through the parts bag they gave me of broken parts to see if the piston top is still there. Also the tune was a canned map that matched the engine precisely with a PC3.

So moving forward - replacement crank, forged pistons, new cylinders, all bearing SAOP, different set of heads.  We will see if we can reuse the SE Oil pump and Cam Plate and rockers.  Just trying to avoid whatever caused the failure, and when you don't know for sure it just leaves you a little uneasy.  We all love that mystery don't we?

Thanks to all.

Thing about detonation is it will raise the temps in the chamber fast and big time. Could explain the blued pin and why the piston did a melt down to the point it just plain fell apart if the duration of the detonation was long enough. It might not even been audible in this case.

Ron

[FXDBI]

I really appreciate all of the input.  I am not an expert, just a learner.  Just haven't seen blued wrist pins before.

When the piston broke the rider was going 80 and pulled the clutch immediately.  However there was just enough rotation to twist the front rod.  So the crank is junk.  Interestingly enough the oil pump looks unscarred and all the bearings roll but they will still be replaced SAOP.  Basically the only thing going forward is the SE cam plate and oil pump and rockers and the crank cases.

I did check the piston oiler however not with regulated air pressure.  I will do that.  Thanks for the tip.  I will also check the rod bearings for looseness and see if the destroyed piston top is in that baggie of parts they gave me to see what it looked like.

The surviving rear piston had no signs of detonation and was completely shiny and clean like new even on the underside.  It also had a blued wrist pin.  Initially I had just assumed that it was understandable for a cast piston to break, but then looking at the surviving piston it showed a lack of cooling.  Could a tune be so far off that the piston would overheat enough to turn the pin blue leading up to the piston failure?  I think I will dig through the parts bag they gave me of broken parts to see if the piston top is still there. Also the tune was a canned map that matched the engine precisely with a PC3.

So moving forward - replacement crank, forged pistons, new cylinders, all bearing SAOP, different set of heads.  We will see if we can reuse the SE Oil pump and Cam Plate and rockers.  Just trying to avoid whatever caused the failure, and when you don't know for sure it just leaves you a little uneasy.  We all love that mystery don't we?

Thanks to all.

Could have been the tune or a number of things combined. How many miles on it after the 95 was done? and who did the 95?  Some pictures would make it easier to figure out wtf happened. Other wise its all a bunch of guessing and a bunch of guess work. Lots of cast pistons out there doing just fine.  Bob

[Flyer]

The engine had 5,000 miles after someone else installed a SE 95" kit with the 10:5 pistons, SE Oil pump and hydraulic conversion cam plate and some woods ( I think tw6) cams.  All bolt in and stock heads.  At that time they put a PC3 on it with a canned tune.  Owner said it ran great.  I will try to post a pic later but in the meantime just imagine you are looking at the bottom of a "brand new" piston with a piston pin blue where is rotates in the piston.  The piston was actually that shiny.

One thing about this rider, he always rides hard.

[Flyer]

Thing about detonation is it will raise the temps in the chamber fast and big time. Could explain the blued pin and why the piston did a melt down to the point it just plain fell apart if the duration of the detonation was long enough. It might not even been audible in this case.

Ron
[/quote]

Maybe the rear piston with the blued pin was ready to follow the front.  I really will try to post some pics up,  gonna take a day or two though.

[FXDBI]

The engine had 5,000 miles after someone else installed a SE 95" kit with the 10:5 pistons, SE Oil pump and hydraulic conversion cam plate and some woods ( I think tw6) cams.  All bolt in and stock heads.  At that time they put a PC3 on it with a canned tune.  Owner said it ran great.  I will try to post a pic later but in the meantime just imagine you are looking at the bottom of a "brand new" piston with a piston pin blue where is rotates in the piston.  The piston was actually that shiny.

One thing about this rider, he always rides hard.

Sounds like a failure due to a number of things. Probably burnt up and seized the piston pulling it apart pins are blue from the heat of the piston top. A PC3 will never give you a adequate tune will all those changes, it needed a flash tuner to make timing adjustments.  There will be scrap metal all through that B-engine now and it will need to come out and apart to do a proper job or you will just have a repeat. 5000 miles isn't many miles after a build and not being done properly is the root cause of the failure. Everybody thinks they are a mechanic.  Bob

[Propflux01]

I can't help but wonder if the builder installed new intake manifold o-rings or just reused the old ones? Thinking maybe a good vacuum leak and resulting lean conditions leading to detonation?

[koko3052]

If you didn't notice it riding, the tuner sure would have.

[KingofCubes]

Be sure to remove and clean the oil tank.

[prodrag1320]

sounds like it was detonation,but it would have been pinging like crazy to be bad enough to destroy a piston,and the plugs would have showed massive signs of detonation.surprised no one noticed that.plus im wondering about the "SE 10.5-1 CAST pistons",SE never made a 10.5-1 piston (ide never run 10.5-1 or above with a cast piston anyway)

[jbexeter]

could it have been a downshift instead of an upshift?

I recall years ago a friend was running his duke hard, high revs in 3rd meant to change into 4th but changed into 2nd, pistons looked like twisted rock strata, what's left of them.

as I recall he also had "no idea" what caused it, until he later admitted it.

[Flyer]

UPDATE!

It took awhile to work through some issues on this engine. I took the pieces over to Mike Stegman at Latus in Gladstone Oregon.  We put quite a few heads together.  These are my observations and where I am at while reassembling this engine.

First a few observations.

1.  Cast SE pistons front one destroyed on a 5,000 95" kit with SE hyd cam plate conversion.  The engine had previously run 17,000 no issues.  The person who put the kit on was definitely not an "engine tech" guy if you know what I mean.  Also a rocker armbroke and was repaired in that 5,000 miles.

2.  Both piston pins were BLUE from heat.

3.  Surviving piston oiler was not plugged.

4.  Heads showed no signs of detonation.

The conclusions we all came to was a lack of oil, so where was it losing pressure?

A. I measured the lifter bores were fine.  New lifters are fitted.

B.  Every oil passage was carefully inspected and test fine.  The oil passage in the old crank was not plugged.  A replacement crank was fitted.  Of course all new bearings went in the engine.

C.  Discussions about the SE conversion plate led me to check the oil passage plugs.  All of the plugs took one to two turns to get them up to 55 INCH lbs.  These plugs were not loose, but not tight either.  So- possible oil pressure issue.

D.  The SE oil pump and plate had no scoring issues so was reinstalled after all the oil passages were confirmed to be clear and new bearings fitted.

E.  I am sure the previous mechanic did not use NEW bolts for the cam chain gears.  The new bolt appears to have a thread locker compound on them.  I am sure lots of people reuse the old bolt but can see how doing so could result in some loss of oil pressure.

F.  Rebored cylinders and new SE forged pistons are installed, along with a fresh set of mildly ported heads.  A power vision with a canned tune for break in followed by a tuning session at Latus at 500 miles will follow.

So that's where I am at,  just wanted to share where all the head scratching ended up.  Thanks for all the input and if you have any other thoughts before I button this thing up I would like to hear them.