Failed Wrist Pin Bearings

[jonnyrebel2004]

I had the woods port, by Eric Gorr, done to my motor and got it back last week. I thought while I was at it I would just buy a Wiesco pistone kit and replace the piston, rings, and wrist bearings. So I put it all back together and everything went in very smoothly. I broke the motor in properly and was very cautious when breaking it in not to over do it. I got it jetted right, by doing a plug chop test and thought I finally had it finsihed. We then headed off to Little Sahara for the weekend. It ran GREAT. So I decided to have it put on the dyno while I was there to double cheak my jetting. It said I was just a little rich on my mains but nothing to worry about. This was on Sunday morning... It ran great the rest of the day Sunday until about 5:00 it acted like it was starving for gas and died on me. I messed with that for a few min and got it started and it ran just as good as it did all day. I was going around a turn and it started to lug like it was starving for gas so I hammered it to try to get gas to it and my rear wheels locked up and it died. Upon trying to kick start it I found out the motor was locked up. So we came home today and tore it apart only to find that the wrist pin bearings on the right cylinder has came apart and went everywhere in my motor. I now have parts of wrist pins sticking out the top of my piston. It scored the side of the cylinder so bad it looks like it is going to need to be re-sleved. When I pulled the other piston out I found that the caseing around the wrist pins was starting to fall apart too and it would have only been a matter of time before it went too. I bought the wiesco set off Ebay. The went in smooth, I didnt have to force anything in. I wanted to know if it was a bad set of wrist pins or what that caused them to do this? Im so sad just when I thought shee was finished it is even a bigger mess than I had. Sorry this post is so long.

 

Thanks Travis

[fastbanshee4u]

I had the woods port, by Eric Gorr, done to my motor and got it back last week. I thought while I was at it I would just buy a Wiesco pistone kit and replace the piston, rings, and wrist bearings. So I put it all back together and everything went in very smoothly. I broke the motor in properly and was very cautious when breaking it in not to over do it. I got it jetted right, by doing a plug chop test and thought I finally had it finsihed. We then headed off to Little Sahara for the weekend. It ran GREAT. So I decided to have it put on the dyno while I was there to double cheak my jetting. It said I was just a little rich on my mains but nothing to worry about. This was on Sunday morning... It ran great the rest of the day Sunday until about 5:00 it acted like it was starving for gas and died on me. I messed with that for a few min and got it started and it ran just as good as it did all day. I was going around a turn and it started to lug like it was starving for gas so I hammered it to try to get gas to it and my rear wheels locked up and it died. Upon trying to kick start it I found out the motor was locked up. So we came home today and tore it apart only to find that the wrist pin bearings on the right cylinder has came apart and went everywhere in my motor. I now have parts of wrist pins sticking out the top of my piston. It scored the side of the cylinder so bad it looks like it is going to need to be re-sleved. When I pulled the other piston out I found that the caseing around the wrist pins was starting to fall apart too and it would have only been a matter of time before it went too. I bought the wiesco set off Ebay. The went in smooth, I didnt have to force anything in. I wanted to know if it was a bad set of wrist pins or what that caused them to do this? Im so sad just when I thought shee was finished it is even a bigger mess than I had. Sorry this post is so long.

 

Thanks Travis

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sounds to me like you need to make a phone call and bitch.what kind of oil and did you mix it?

[jonnyrebel2004]

sounds to me like you need to make a phone call and bitch.what kind of oil and did you mix it?

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You mean like crankcase oil or premix oil?

[Duninshee]

Wiseco takes very good care of their customers I would give them a call and explain what happened. I had a defective piston and they took care of all the work. They even threw down for shipping. I had it back in 2 weeks. Call em. It won't hurt.

 

sounds to me like you need to make a phone call and bitch.what kind of oil and did you mix it?

 

He is asking what type of oil do you mix in your gas and at what ratio. I.E. (32:1, 40:1 ect....)

[SANDSTAR]

Save all of the packing and boxes that your piston kit came in. Wiesco won't question it when you send the stuff back in their own packaging. They should pay for the bore, too. Check out the head,as that could be damaged as well. If it needs sleeves, you might think about a big bore kit

[SDD]

Why bother with doing a big bore kit if your cylinders are toast. Perfect time to step up to Cheetah Cub cylinders. As far as your failure it sounds like lack of lubrication. What does the bottom of the piston look like on the side that didn't let go? Does it have a black spot under the piston? Since your the one that put everything back together it's going to be hard to prove that something actually failed. Did you lube the wrist pin bearing when you assembled the motor... I know you probably did but what did you use?

[RBD]

Wrist pin bearing failures are not that common... Two questions; Were the bearings new? And are you sure that it wasn't the clip that let go and did the damage?

 

I have seen many problems from piston pin clips coming out. Some Wiseco pistons are hard to get the clips seated properly (not enough room as it hit up against the pin before seating).

[jonnyrebel2004]

Wrist pin bearing failures are not that common... Two questions; Were the bearings new? And are you sure that it wasn't the clip that let go and did the damage?

 

I have seen many problems from piston pin clips coming out. Some Wiseco pistons are hard to get the clips seated properly (not enough room as it hit up against the pin before seating).

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All clips were still in place. This was definately a bearing failure. They were new bearings and were lubed prior to installation. Engine ran probably 10 hours before failure. Right one came apart and did massive damage. Left one bearing cage was gone with only needles and cage ends left. Go figure......

[badassbanshee479]

my brothers 99 yz125 did the same thing when we rebuilt it with the wiseco top end kit, I seem to think that the rod end is egg shapped and the bearing got bet out of it, I am going to take the crank and rod some where and have it checked I will let you know what I come up with

[banshee04le]

What octane fuel are you running, whats your static compression and how much

timing advance are you at? Your description of how it would run sounds like you

were experiencing pre-detenation. Pre-det will hammer your bearings harder than

anything until it blows a hole in your piston...your bearing came apart before that

happened. Severe pre-detonation under hard accelaration will feel like your starving

for fuel as the bike stalls but you will feel some vibration or shake...thats called

the "death rattle". I had a wrist pin bearing cage fail due to this but luckily I caught it on

teardown before it came apart. It was a wiseco bearing also. I buy oem bearings

now.

[RBD]

What octane fuel are you running, whats your static compression and how much

timing advance are you at?  Your description of how it would run sounds like you

were experiencing pre-detenation.  Pre-det will hammer your bearings harder than

anything until it blows a hole in your piston...your bearing came apart before that

happened.  Severe pre-detonation under hard accelaration will feel like your starving

for fuel as the bike stalls but you will feel some vibration or shake...thats called

the "death rattle".  I had a wrist pin bearing cage fail due to this but luckily I caught it on

teardown before it came apart.  It was a wiseco bearing also.  I buy oem bearings

now.

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That sounds like a very good explanation to me.... good thought!

[jonnyrebel2004]

I am running AV100LL. I have a Noss cool head with 20cc domes and I run Engine Ice coolant. I have +4 timing. I dont know my cmpression because my gauge is broke. Based on this do you still think it was pre-detonation? I talked to David a Noss before I ran it and he said AV100LL would be ok with my setup, so I dont know what went wrong.

[banshee04le]

I am running AV100LL. I have a Noss cool head with 20cc domes and I run Engine Ice coolant. I have +4 timing. I dont know my cmpression because my gauge is broke. Based on this do you still think it was pre-detonation? I talked to David a Noss before I ran it and he said AV100LL would be ok with my setup, so I dont know what went wrong.

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What plug are you running? BR8 or 9 would be good. I would suggest running 110 for

an extra margin of safety. Anything less than 110 octane is not "race gas"

If the bike was shutter stalling on you, I think that was the problem.

[jonnyrebel2004]

What plug are you running? BR8 or 9 would be good.  I would suggest running 110 for

an extra margin of safety.  Anything less than 110 octane is not "race gas"

If the bike was shutter stalling on you, I think that was the problem.

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What do you shutter stalling? So are you saying my ocatne was too low? I am running what ever plug is stock...I think its a B8ES...does that sound right?

[banshee04le]

What do you shutter stalling? So are you saying my ocatne was too low? I am running what ever plug is stock...I think its a B8ES...does that sound right?

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Your plug is fine. I'm just saying that a bike that is running really strong and

then intermittently feels like it wants to stall on you and then a wrist pin bearing goes

sounds like predetonation. Get a hold of a compression gauge. Maybe you got

some bad fuel. Run 110 and get you some 18cc domes and the bike will rip even

harder.