Bottom End Rebuild

[mike11743]

I have a couple questions reguarding the crank bearings in my 01 Blaster. I have been hearing a sort of very light knock in my motor for some time now. It is pretty noticible at idle, but either goes away or gets drowned out at idle. I have a very small amount of movement up and down in the stator which makes me think crank bearing is starting to go. This movement however is so slight that I can barely feel it, and definitely not see any movement. Well anyways to get on to my questions...I have started pulling apart a junk motor that I have for practice and I have successfully split the cases. The crank slid out of the left side case, but the other bearing and crank are still all stuck together in the right side case. How do I go about seperating all this? Also can I just beat the old bearings out with a socket or something?

 

[Antec1200X]

was gunna say stuff it in a oven,but chances are who has a oven ppl can stuff motor parts in

 

[Busted Warrior]

There is a tool at harbor freight that allows you to separate the bearings from the crank. And use a steering wheel or harmonic balancer to push the crank out of the side case.

 

[mike11743]

Does anyone think I should continue riding this thing? I have like 100ish lbs of compression, but I can feel a very very slight movement in the stator. Like i'm talking barely any movement. It runs fine and the plug shows it's not running lean.

And then my second question. I have an extra motor with bad crank bearings that I was practicing taking apart. I'm using hammers and screwdrivers just to see if I could do it, and I got it all apart, but bent the crank which doesn't bother me because it was junk anyways. So I want to take my good motor aprat, but i'd obviously be using the proper tools. So what exactly do I need?
I have the flywheel puller and a homemade clutch holder. I know I need a torque wrench, a harmonic balancer puller to seperate the crank and case. Anything else?

 

[Braaaptor]

Mike, you are taking a chance running an engine with questionable bearings. It may run fine for awhile longer, or a bearing may fail altogether and leave you stranded and/or cause more damage. If you have only 100psi compression in your 'good' engine, it is already needing a new top end. Vertical play in your main bearings also sounds like it is almost time for crank bearings. Sure, it runs OK for the moment, but there's no telling for how much longer. Plus, damaged bearings can cause an air leak and you'll lean it out and fry a top end if the damage/wear gets worse over time. Which it will.

If I were you, I'd stop running the Blaster for now and go ahead and rebuild your engine before it dies altogether. The 'knock' you are hearing is probably NOT the crank bearings, rather, it is 'piston slap'. This problem needs to be fixed before it gets worse and you break a piston skirt. If it isn't piston slap, its a rod bearing. Either way, not good.

To get the cases apart, use a tool called a case splitter. I think you can get one from Motion Pro. Not 100% sure. Anyhow, there is a DIY thread here on the forum on how to split your cases, using this tool. NEVER beat on or pry things apart, no matter how badly you want to get in there. Not trying to be a dick, just sayin'...

 

[mike11743]

Yeah I guess i'll just stop riding it. I was gonna try to get like 10 more hours which is like 2 months of riding for me out of the top end before rebuilding it, but if the crank bearings are bad, might as well do it now i guess before i do any major damage. Oh and as far as beating the old motor apart, I just wanted to see how it all worked because if there were like a million pieces inside and I didnt think I could handle it, I'd just let someone else do it so I don't screw up my good motor.