Need help on busted piston cause

[koko3052]

I can't see loosing a bunch of oil press. from pipe plugs just not up to torque. Have no other thots about the missing oil.

[Matt C]

Post a picture of the underside of both pistons.

[kd]

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. 

I'm a little late to the party here but it seems that an engine with 5,000 miles on it should have some sort of carbon staining on the tops of the pistons whether externally vented or not. The above statement seems to indicate a clean and shiny top surface. I'm thinkin a lean tune here and would recommend not doing that over again. Get the AFR confirmed on initial start up and have it broken in on the dyno while being tuned.

[02FYRFTR]

Was the interconnect seal that goes between the right side case and the balancer frame in position when you disassembled and is it in the correct position now !!

[les]

Was the interconnect seal that goes between the right side case and the balancer frame in position when you disassembled and is it in the correct position now !!

Make sure to pressure test the interconnect seal.  It should be holding from 28 - 35 lbs. of pressure.  Preferably, the full 35 lbs.

[Flyer]

Post a picture of the underside of both pistons.

Both pistons clean and shiny underneath, normal carbon build up on top. 

KD my statement was misleading, I should have said clean and shiny only on the bottom, normal carbon build up on top.  Dyno breakin would probably be a great idea.

[Flyer]

Was the interconnect seal that goes between the right side case and the balancer frame in position when you disassembled and is it in the correct position now !!

Yes the seal was there and intact. The engine cases had not been disassembled for the 95" build. 

[Flyer]

Was the interconnect seal that goes between the right side case and the balancer frame in position when you disassembled and is it in the correct position now !!

Make sure to pressure test the interconnect seal.  It should be holding from 28 - 35 lbs. of pressure.  Preferably, the full 35 lbs.

New seal is in place,  how do you check the pressure?

[Flyer]

Again, thank you all for your suggestions.  As it is when we fire it up for the first time there will be a mechanical oil pressure gage up front where the sending unit goes.  So if the oil pressure is up and the lifters settle down quickly I will feel good enough to go to the tuner.

[02FYRFTR]

Was the interconnect seal that goes between the right side case and the balancer frame in position when you disassembled and is it in the correct position now !!

Make sure to pressure test the interconnect seal.  It should be holding from 28 - 35 lbs. of pressure.  Preferably, the full 35 lbs.

New seal is in place,  how do you check the pressure?

Refer to any of the Softail manuals and you will be able to check, I use a leak down kit to check

[Flyer]

 

Was the interconnect seal that goes between the right side case and the balancer frame in position when you disassembled and is it in the correct position now !!

Make sure to pressure test the interconnect seal.  It should be holding from 28 - 35 lbs. of pressure.  Preferably, the full 35 lbs.

New seal is in place,  how do you check the pressure?

Refer to any of the Softail manuals and you will be able to check, I use a leak down kit to check

Thanks, I did not know if it was in the manual just didn't have time to look yet.