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My crank went out in my crf250r last week and we think it was due to lack of maintenance from the previous owner because I haven't had it long. I'm on a budget and after spending a lot of money on other parts in the motor, I was looking at buying a used crank for it. Is this a good idea for somebody on a budget or do I need to save up a couple hundred more dollars to buy a new one?

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I wouldn't recommend a used crank. If someone has removed theirs it's likely due to timed maintainence. There is a lot of work involved to replace a crank so why chance more work and bigger problems if the used part fails. Fix it right.

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New crank rebuild kit is cheap if you find a reasonable place to get it pressed.

 

The price of even a new crank isn't much compared to the work of installing it.

 

NO on used.

 

Are you going to install yourself?

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RBD will do a rebuild for $60 plus $129 connecting rod and bearing. I'd trust that over one of those Chinese cranks anyday

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RBD will do a rebuild for $60 plus $129 connecting rod and bearing. I'd trust that over one of those Chinese cranks anyday

What exactly do they do to rebuild it? And a local mechanic is installing it for $200.

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Next comes the question - Should I put all new bearings and seals when the lower end is apart?  Should I put new clutch baskets in while it is off?  New piston?  Valve job?  Paint frame while engine is out?  Rebuild carb?

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Next comes the question - Should I put all new bearings and seals when the lower end is apart? Should I put new clutch baskets in while it is off? New piston? Valve job? Paint frame while engine is out? Rebuild carb?

Funny thing is, I already did all that. Everything in the motor was replaced 3 weeks ago except the crank, valves, camshaft, and cam chain because they were "In good condition"- obviously not. That's why I'm on such a tight budget now.

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In that case, I would tend to blame the mechanic and not the previous owner for crank failure.

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Funny thing is, I already did all that. Everything in the motor was replaced 3 weeks ago except the crank, valves, camshaft, and cam chain because they were "In good condition"- obviously not. That's why I'm on such a tight budget now.

Call this guy and i bet he will assemble it for less money too. Not just a local lawn mower mechanic.  http://www.kenoconnorracing.com/   Prices on the website 139 bucks for a rebuild using Pro X   /   Stock honda bearings . 

Edited by Beau 88

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In that case, I would tend to blame the mechanic and not the previous owner for crank failure.

Well when he was rebuilding it he said it looked like they ran the bike without oil a bit cause he could smell that the inside was burnt. What he neglected to tell me was that this could lead to premature crank failure so we reassembled without replacing the crank.

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What exactly do they do to rebuild it? And a local mechanic is installing it for $200.

 

The rod has a bearing where it connects to the crank, you replace that because they wear out and get sloppy. If the PO ran it with no oil that's probably not the only bearing you'll need to replace unfortunately. Do all the bearings in the bottom end, check the cylinder for signs of damage, the cam lobes may also have damage if ran for long with no oil. You'd honestly may be less of a headache to just buy an engine off ebay.

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The rod has a bearing where it connects to the crank, you replace that because they wear out and get sloppy. If the PO ran it with no oil that's probably not the only bearing you'll need to replace unfortunately. Do all the bearings in the bottom end, check the cylinder for signs of damage, the cam lobes may also have damage if ran for long with no oil. You'd honestly may be less of a headache to just buy an engine off ebay.

I've already replaced all bearings in the bottom end just before the crank went bad. Do I have to do this again? And it didn't completely seize or anything I just saw a bunch of shavings in my oil filter. So do I have to replace everything that the oil may have come in contact with?

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Well when he was rebuilding it he said it looked like they ran the bike without oil a bit cause he could smell that the inside was burnt. What he neglected to tell me was that this could lead to premature crank failure so we reassembled without replacing the crank.

 

You're telling us that your mechanic suspected that the motor was run without oil, replaced all the bearings, but reinstalled the old crank?  Either he's an idiot or more concerned with making a buck then the quality of the work he does. I'd have him replace the crack free of charge, that is unless you agreed to reinstall the crank though he suggested not to. 

 

Like mentioned before have your old crank rebuilt, unless it's a Wiseco.  You will also want to replace the timing chain, something that should always be done with a full rebuild.

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You're telling us that your mechanic suspected that the motor was run without oil, replaced all the bearings, but reinstalled the old crank? Either he's an idiot or more concerned with making a buck then the quality of the work he does. I'd have him replace the crack free of charge, that is unless you agreed to reinstall the crank though he suggested not to.

Like mentioned before have your old crank rebuilt, unless it's a Wiseco. You will also want to replace the timing chain, something that should always be done with a full rebuild.

I am new to the mechanics of a bike and the mechanic said that the crank was in good condition and that there was no need to replace it so I trusted him and did not replace it. I figured that a guy that has rebuilt tons of motors has a bit more knowledge than a kid that hasn't had a bike in 5 years.

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Lot of work to rebuild a bottom end. Spend the extra money and get a new quality crank. You will pry end up regretting it if you dont.

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I've already replaced all bearings in the bottom end just before the crank went bad. Do I have to do this again? And it didn't completely seize or anything I just saw a bunch of shavings in my oil filter. So do I have to replace everything that the oil may have come in contact with?

 

The shavings you were seeing was the start of the end of the crank.

If you've already replaced all the other stuff just split the cases and replace or rebuild the crank.

You should be good to go for quite some time.

 

Some guys here are badmouthing your mechanic. I don't know the guy from a hole in the wall.

He probably measured the run out and clearances, and it all measured good.

Unless he's familiar with Honda rod failures, he wouldn't know the rod was on its way out.

That doesn't make him a bad mechanic.

He might be very good at removing and replacing, and reassembling, everything back to spec.

That in itself is an accomplishment today.

 

crank tolerances don't mean shit in the life span of a crank.

Its been said in this forum a thousand times... 

You found this out the hard way, but now you know. That make you more knowledgeable than a lot of folks

Edited by nesc103y

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