crank bearing failed in 10 hours

[schrode]

I'm not sure but i doubt they balanced the crank.

i'd probably think that was the issue unless something else is glaringly obvious.

 

they balance them during manufacturing but the shipping process can be a rough deal. lots of banging around. i always have a good shop balance a new crank for me before i install it. 

[woods guy]

I spoke with the shop and they think the failure came from dirt getting past the seal on the stator side, but said they won't know for sure until they take it apart.  They offered to tear it down and fix it for free if they determine it's their fault, but the expense will be on me if they find otherwise.  Rather than deal with the inevitable fight I decided to just order the parts and do it myself this time. It cost me about $400 but at least I know it will be right.  I'll take a few extra steps to seal the stator cover water tight too since my flywheel and weight are 100% covered in rust and as I said before the stator cover had a lot of dirt inside it when I removed it.

[MrBlahh]

yeah that sounds like it caused it, any damage to the piston/plating?    afaik nobody balances 2 stroke cranks but they do true the two case halves together

[woods guy]

yeah that sounds like it caused it, any damage to the piston/plating?    afaik nobody balances 2 stroke cranks but they do true the two case halves together

 

I won't know for sure until I tear it apart in a couple of weeks, but I hope not.  I've never heard of truing a case before.  I always thought the pins in the case halves do it for you

[MrBlahh]

sorry that was a typo,  true the crank halves,  brass mallet and machinist v blocks

[harryhandshake]

i'd probably think that was the issue unless something else is glaringly obvious.

 

they balance them during manufacturing but the shipping process can be a rough deal. lots of banging around. i always have a good shop balance a new crank for me before i install it. 

 

 

they dont balance anything. crank is trued up and sent out the door. and half the time they aint even very true.  dont kid yourself, these aint hand built ferarris

Edited May 28, 2014 by harryhandshake

[zotis777]

they dont balance anything. crank is trued up and sent out the door. and half the time they aint even very true. dont kid yourself, these aint hand built ferarris

It's like you neglected to watch the hotrods how it's made...... they're trued accurately before they're shipped.

[woods guy]

I just split the case and found a little water in there. The bearings are rusty and wet, not oily and the wrist pin was real hard to get out of the piston.

I dunked it in a swamp when it had about 5 hours on it so that must have killed it. It looks like I'll have to be more careful with this bike than I'm used to. My drz would have taken it like a champ

Edited May 31, 2014 by woods guy

[woods guy]

I took the cylinder apart today and found water damage in the top end. The power valve was stuck open and the seals around the power valve sleeves had failed and the sleeves themselves are rusty. I'm going to replace the sleeves and seals and clean it up real good before reassembly. What I'm not sure about is the piston. It looks good but the wrist pins was difficult to press out. It took a few hits with a hammer and a socket to get it out and it was run for 5 hours with water in the bike. Am I crazy to reuse the piston? It only has 10 hrs on it

Edited June 3, 2014 by woods guy

[KTMRider4Life]

I took the cylinder apart today and found water damage in the top end. The power valve was stuck open and the seals around the power valve sleeves had failed and themselves sleeves are rusty. I'm going to replace the sleeves and seals and clean it up real good before reassembly. What I'm not sure about is the piston. It looks good but the wrist pins was difficult to press out. It took a few hits with a hammer and a socket to get it out and it was run for 5 hours with water in the bike. Am I crazy to reuse the piston? It only has 10 hrs on it

Straight nuts if you ask me, the part about hitting the pin with a hammer is what really worries me, other than that you coudl measure it and know if it's good minus anything you could see obviously.

[woods guy]

Straight nuts if you ask me, the part about hitting the pin with a hammer is what really worries me, other than that you coudl measure it and know if it's good minus anything you could see obviously.

 

I should probably clarify what i mean by hit it out with a hammer.  I placed a socket extension on the end of the wrist pin and wrapped my hand around the back side of the piston and tapped the wrist pin into my hand.  I hit the wrist pin about as hard as one would drive in a finish nail.  Should the piston be replaced?

[KTMRider4Life]

I should probably clarify what i mean by hit it out with a hammer.  I placed a socket extension on the end of the wrist pin and wrapped my hand around the back side of the piston and tapped the wrist pin into my hand.  I hit the wrist pin about as hard as one would drive in a finish nail.  Should the piston be replaced?

It's cheap insurance but if it looks good and measures fine then it should be good. 

[MrBlahh]

I just split the case and found a little water in there. The bearings are rusty and wet, not oily and the wrist pin was real hard to get out of the piston.

I dunked it in a swamp when it had about 5 hours on it so that must have killed it. It looks like I'll have to be more careful with this bike than I'm used to. My drz would have taken it like a champ

 

well now you know why it failed,  whenever I dunk a bike I make sure I get all the water out,  did it sit after you turned it into a submarine?  Running temp should have boiled off any water left in the power valve area 

[woods guy]

No unfortunately I just pulled it out and kicked it a lot to get it started. I ran it about an hour and then parked it for a week before running it again. The ride the following week is when I realized something was wrong.

[moparmiller]

I took the cylinder apart today and found water damage in the top end. The power valve was stuck open and the seals around the power valve sleeves had failed and the sleeves themselves are rusty. I'm going to replace the sleeves and seals and clean it up real good before reassembly. What I'm not sure about is the piston. It looks good but the wrist pins was difficult to press out. It took a few hits with a hammer and a socket to get it out and it was run for 5 hours with water in the bike. Am I crazy to reuse the piston? It only has 10 hrs on it

Ive had my last 2 piston pins be tight but the crank and rod are tight. Same deal with drifting the pin out.