Main Bearing Failure

[TRX55]

HEY,NEED A LITTLE HELP, I HAD THE BOTTOM END OF MY 95 KX 250 REDONE WITH NEW MAIN BEARINGS,SEALS AND HOT ROD KIT. I NEED TO KNOW IF ANYBODY KNOWS OF ANY PROBLEMS WITH MAIN BEARINGS ON THIS MOTOR. I'AM GETTING LOUD GROWLING NOISE FROM THE LOWEND WHEN I KICK IT OVER WITH THE PLUG OUT. A COUPLE OF RIDES AGO I HEARD A SQUEEL, SOUNDED LIKE A DRY BEARING, THEN IT WENT AWAY AND THE LAST RIDE, WHEN I WOULD LET UP ON THE THROTTLE IN 2ND OR 3RD THE MOTOR REALLY DRAGGED THE BIKE DOWN IN NO TIME. IS THERE SOMTHING THE MECHANIC COULD HAVE DONE OR NOT DONE TO CAUSE PREMATURE BEARING FAILURE OUTSIDE OF BLOCKING THE OIL FEED HOLES WITH THE CRANK SEALS. THANX FOR ANY USEFUL INFO

 

[Honda26]

REALLY NO WAY THAT SUCKS DUDE SORRY!!!!!!!

no really, dont type in caps. its so annoying.

 

[motodawg]

Doesn't sound good. Take it back to the mechanic now. Do not ride it any more. Something was done wrong. Perhaps the crank halves were not aligned properly when pressed back together or maybe they "slipped" after the fact. If tranny oil has gotten in from a seal torn during assembly or misaligned cases it can also cause symptoms like these. Whatever the reason, it needs to be pulled apart and checked. :ugg:

 

[DEANSFASTWAY]

Maybe he didsnt set the side clearance correctly? I have seen that happen before too tight =no good . It would be pretty hard to block the oil holes . Take it back and check it over. GOOD LUCK

 

[TRX55]

I did use a couple of ounces of tranny oil in the last 4hrs of riding, could be something........ As far as the clearance problem, if i check the thrust bearing clearance and find that it is excessive for 30hrs of run time, could that be an indication of to little or no side clearance?

 

[motodawg]

If you're using tranny oil you've got a serious problem. One that can escalate quickly if you continue to run the bike. Pull the top end. When my sons KX blew a main seal at Cooperland a couple years ago, the bike had lost power, the bottom end was noisy and it just wouldn't rev out. Pulling the cylinder after his moto found that the thrust bearings were already disintegrating, there was mucho play there, and tranny oil was consumed. Had to be rebuilt from the crank up. I know it's a pain in the butt... but you have to pull it apart. No way around it.

 

[TRX55]

Well i took the bike up to guy that did the bottom rebuild and told him the problem i was having when i ride it for a while, he didn't seem to think anything was wrong, even when i insisted that something wasn't right! So i'll just assume he doesn't want to deal with a possible comeback. I took it back home and took it apart, first the top end, then the right side cover. The top end is due for a new piston but the crank is still pretty solid,no binding,excessive play and there is no sign of tranny oil any where, go figure.... The only thing i found worth anything was the powervalve actuator outer and inner bearing felt pretty course when i spun them. Mabye that could be the squeel i heard from time to time. In a nutshell that is about all i could find wrong.. I,ll just put it back together with the new top end and hope for the best! By the way is there anything that could cause the motor to feel so held back when it gets ridden hard for a while? tranny??????????

 

[TFR]

When the guy did the bottom-end rebuild he may not have centered the crank in the cases when he put them together. Alot of D.I.Y. make this mistake and everything might seem ok 'til the bearings get hot. Then your crank could start rubbing against a main bearing. I've seen this alot. If you still have your top end off, stick a feeler gauge down between the crank and case. Both sides should be equal and your crank should spin freely. GOOD LUCK. Jim-2-fastracing.

 

[TRX55]

Hey, Jim that's a pretty good idea, i'am still waiting on the new piston, so i'am gonna check it out. If the bearings are heating up, should the bearings be showing any signs of wear, such as noise when i spin the crank holding the rod end? Would only one bearing be affected if he didn't center it? Last of all should i have any minimal end play when i push and pull on the crank? I appreciate any info on this, I would really like to get a few more harescrambles in before the end of the year comes! Thanks !

 

[TRX55]

.Hey man i couldn't wait, i had to check it out before bedtime. I'am getting .013 between the crank and right case and .054 on the left, pretty obvious to the eye. Is this just cause to have him redo it at no charge to me? After all it was a $400.00 job! I tried to find some assembly info out of my factory manual but to no avail. I hope this is the culprit............ Thanks!

 

[TFR]

That tells me that it was never centered. Unless the journals are worn and you can move it from side to side. Then you need a new crank and I don't feel they should have to cover that other than the fact that it should have been caught during the rebuild. If I had done the work I would stand behind it but I'm guessing they're not going to. GOOD LUCK. JIM-2fastracing.

 

[TRX55]

The saga continues...... Well i ran into another unpleasant surprise tonight. I called someone out west who specializes in crank and top end rebuild he told me i could tap the crank on the side that was too close and it would slowly center itself. I proceeded to do so and it had little effect, i only got it to move about .003in. Well as i was checking the side clearance i noticed the left side of the crank was pushed in on each side of the crank pin right where the metal gets thin and the aluminum weights go. I about blew a gasket when i seen that and i know tapping or even slightly hitting the crank shafts would not cause that kind of damage the other crank half only has about .001 side runout, though it really shouldn't have any. I don,t know if this is why the motor seems to be held back when it gets hot. I really think that dude owes me another crank!!!!!! Thanks for all your help, I"ll let you know how it turns out....................

 

[TRX55]

Well, all is good. I'am gettin it redone at no cost, that's pretty cool...................