is crank bearing bad

[steeler2169]

I fouled out my right plug, had smoke and a knock on right side so i pulled head and jugg piston has no scars no nothing, jugg walls look good so where did my knock come from how can you tell if the crank bearing is bad. and what caused my plug to foul out could it be carburator issue? Im lost and need help

[twizted269]

I fouled out my right plug, had smoke and a knock on right side so i pulled head and jugg piston has no scars no nothing, jugg walls look good so where did my knock come from how can you tell if the crank bearing is bad. and what caused my plug to foul out could it be carburator issue? Im lost and need help

how long have you been running the plug? could be just old. also how old is the top end? i had knocking from piston slap. they looked great but just wore out and was way beyond tolerence. with the top end off see how freely the crank moves with no roughness and how much play the bearings have.

[steeler2169]

The plug got put in sat. and fouled sun. The top end i dont know I bought shee used. how often should you rebuild

Edited March 19, 2009 by steeler2169

[steeler2169]

do you just try to move crank up and down to see for free play not actually turning it.

[Koolguyson]

You could have a bad crank seal. That will cause transmission oil to seep in from the clutch side and into the right cylinder. This will cause your right plug to foul.

 

Hard to check crank bearings with the motor together, but you can check rod play.

[liveordie72089]

Check out my rebuild thread.

 

http://www.bansheehq.com/forums/index.php?showtopic=110739

 

There's a video on there that shows a bad crank bearing. You'll be able to know if it is right when you took off your case. Im not sure if that is your problem because if you would of blew a bearing you would of had metal pieces all over your engine. Well one side. and the bottom of the case would of been like mine.

[deckheight]

A bad bearing normally won't foul a plug unless a peice of something is stuck between the electrode and ground prong.

At any rate, if you want to check the bearings... Take off the piston, inspect the little end bearing and wrist pin under good lighting with a 10X magnifying glass. Then visually inspect the big end rod bearing under magnification, then for vertical movement and side clearance. Also check the head and top of the piston under magnification, this will tell you if there is any "cratering" or "pitting" in the combustion chamber and general location. "Cratering" is from something going through the combustion chamber like tiny peices (sometimes not so tiny) or specks of bearing or bearing seperator that are actually pushing material out of the way. "Pitting" is where the material is just eaten away from detonation. If there is no visual indication of a problem or cratering it is almost certain the rod and main bearings are still good :biggrin:

[Koolguyson]

A bad bearing normally won't foul a plug unless a peice of something is stuck between the electrode and ground prong.

At any rate, if you want to check the bearings... Take off the piston, inspect the little end bearing and wrist pin under good lighting with a 10X magnifying glass. Then visually inspect the big end rod bearing under magnification, then for vertical movement and side clearance. Also check the head and top of the piston under magnification, this will tell you if there is any "cratering" or "pitting" in the combustion chamber and general location. "Cratering" is from something going through the combustion chamber like tiny peices (sometimes not so tiny) or specks of bearing or bearing seperator that are actually pushing material out of the way. "Pitting" is where the material is just eaten away from detonation. If there is no visual indication of a problem or cratering it is almost certain the rod and main bearings are still good :biggrin:

 

 

Err? You can't assume one bearing is good just because another is good. Especially if you have a bad seal on one side. If you can't physically spin the bearings in your hand, then you can't check if they are healthy (remember OP, a crankshaft has 4 case bearings that you can not inspect unless you split the cases). I also wouldn't go as far to check the rod with a 10x magnifying glass or the head. If you have an issue there, you will definitely see it with the naked eye.

 

 

[deckheight]

Say what? "I just explained how to check for an indication of problems for all the bearings on a crankshaft assembly, without splitting the cases... And you are kind enough to remind me that there are 4 main bearings... LOL!

Might take a stab at reading it again... Bearing assemblies normally don't just all of a sudden fail, they typically do it gradually. That said, do you honestly think that even the smallest peices of hardened steel going through a combustion chamber will not leave a mark on aluminum? I have caught enough bearing problems (before actual failure) with the use of magnification to know that it is a valid procedure. In fact, it is the only way that I can detect failure early on and I have 20/20 vision up close. Magnification is also the only way that I can tell the difference between pitting and cratering. And no I do not personally use a 10X magnifying glass, I use something a little more "state of the art". However, being that most readers probably don't know what an otoscope is or have access to one... I suggested 10X glass.

At any rate, you know what you can do with your OP junior:biggrin:

 

Err? You can't assume one bearing is good just because another is good. Especially if you have a bad seal on one side. If you can't physically spin the bearings in your hand, then you can't check if they are healthy (remember OP, a crankshaft has 4 case bearings that you can not inspect unless you split the cases). I also wouldn't go as far to check the rod with a 10x magnifying glass or the head. If you have an issue there, you will definitely see it with the naked eye.