Crank harder to turn

Blackjack31
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Blackjack31
I am restoring a 1988 cr125 and had the crank rebuilt, new crank bearings, new transmission bearings, new cylinder, new head. Everything. Well when I put the cases back together and spun the crank I noticed it was very hard to turn. I split the cases again and pressed in the crank bearings more. One went in a little more and the other didn’t. I put it back together and it was a lot easier to turn but still wasn’t just spinning like crazy. I could turn it with my hand no problem but sometimes it would get stuck on the bottom. I’ve read post about them not being in all the way but people were having to turn it with a wrench. It’s not near that hard to turn. But it was a little stiff. My friend said he had his yz250 done and it was like that. The shop said the ball bearings just needed to break in a little. Like I said, it wasn’t a crazy resistance that requires a wrench but I couldn’t just put a little pressure and it spin like crazy. What’s y’all opinions? The motor is now completely assembled and I would rather not go back into it but if it’s messed up then I guess I’ll have to. I pulled the crank into the case halves also. Heard that can be an issue. I’ve put a crank in but didn’t replace the crank bearings when I done it. Apparently new bearings is what can cause the stiffness? Thanks. Sorry for the long description.
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Paul_Pitzonka
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Paul_Pitzonka 9/13/2019 1:03pm
9/13/2019 1:03pm Edited Date/Time 9/13/2019 1:11pm
You need to center the crank (you’re going to get varied opinions on this) ... I normally take a measurement and figure out how much clearance on each side of the crank web is required and center the crank on install... (it’s easy enough to do with a set of long feeler gauges). I freeze the crank and heat the main bearings; then place my desired feeler gauge thickness on the primary side an set the crank in... while leaving the feeler gauges in place install the other case half... crank always spins incredibly free like this... (I’ve never had an issue with a binding crank or any running problems by installing them this way. the ball bearings needing to break in is total Non-sense)... You may be able to center the crank by pulling on the opposite side with the crank installation tool... also some guys give them light taps with soft mallets or dead blows to free them up (I don’t have the courage to do that myself)...
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Blackjack31
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Blackjack31 9/13/2019 2:21pm
9/13/2019 2:21pm
Alright. I will give this a try. Can I do those by taking the clutch cover over, loosening the case bolts, and using the puller? Rather then splitting the cases for a 3rd time?
Paul_Pitzonka
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Paul_Pitzonka 9/13/2019 3:42pm
9/13/2019 3:42pm
Blackjack31 wrote:
Alright. I will give this a try. Can I do those by taking the clutch cover over, loosening the case bolts, and using the puller? Rather...
Alright. I will give this a try. Can I do those by taking the clutch cover over, loosening the case bolts, and using the puller? Rather then splitting the cases for a 3rd time?
Yes, you can try to pull opposite the side that’s bound... I would pull the cylinder so you can watch if it’s moving.

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Blackjack31
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Blackjack31 9/13/2019 4:20pm
9/13/2019 4:20pm
Blackjack31 wrote:
Alright. I will give this a try. Can I do those by taking the clutch cover over, loosening the case bolts, and using the puller? Rather...
Alright. I will give this a try. Can I do those by taking the clutch cover over, loosening the case bolts, and using the puller? Rather then splitting the cases for a 3rd time?
Paul_Pitzonka wrote:
Yes, you can try to pull opposite the side that’s bound... I would pull the cylinder so you can watch if it’s moving.
Geez haha. I’ll give you an update. I gotta put together a yz250 first 🙄
Blackjack31
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Blackjack31 9/13/2019 4:21pm
9/13/2019 4:21pm
I thought that also but the shop is a very popular shop and the bike now has like 50 hours on it. And still runs strong 🤷🏼‍♂️
kb228
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kb228 9/13/2019 5:16pm
9/13/2019 5:16pm
Also had a yz250 that had some resistance on a fresh rebuild. It didnt snag or hang up, just had resistance.

I was told to take a dead blowhammer and whack the end of the crank to “set” the crank in the bearings. It helped a lot.

BUT, Since youre snagging up it sounds like a bearing isnt straight in the bore
Paw Paw 271
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Paw Paw 271 9/13/2019 10:17pm
9/13/2019 10:17pm Edited Date/Time 9/13/2019 10:20pm
Sounds like the crank is too far into one bearing. Most likely the clutch side. Just give that end of the crank a good smack ( towards the center) with a soft ( brass) or rubber hammer. The other possibility is that the crank is not trued correctly. Check the crank ends with a dial indicator when turning it to be sure. If not true, remove it and have it trued correctly.

Paw Paw
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Blackjack31
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Blackjack31 9/14/2019 1:08am
9/14/2019 1:08am
Paw Paw 271 wrote:
Sounds like the crank is too far into one bearing. Most likely the clutch side. Just give that end of the crank a good smack (...
Sounds like the crank is too far into one bearing. Most likely the clutch side. Just give that end of the crank a good smack ( towards the center) with a soft ( brass) or rubber hammer. The other possibility is that the crank is not trued correctly. Check the crank ends with a dial indicator when turning it to be sure. If not true, remove it and have it trued correctly.

Paw Paw
I do believe it could be the clutch side because it was moving pretty freely until I put the clutch basket on and that’s when it got a tighter. Also, somebody had beat the end of the crank on the stator side and messed up the threads. How do you avoid this? I’ve even messed up threads using a rubber mallet.
Paul_Pitzonka
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Paul_Pitzonka 9/14/2019 7:51am
9/14/2019 7:51am Edited Date/Time 9/14/2019 7:55am
This... I was under the assumption the crank was hard to turn by itself... if it’s binding only when attached to the clutch you definitely have a bent shaft or part... take a dial indicator and see if you can find any excessive runout on any of the shafts...
Blackjack31
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Blackjack31 9/14/2019 1:24pm
9/14/2019 1:24pm
But why would the clutch make it harder? The clutch isn’t connected to the crank shaft.
Paul_Pitzonka
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Paul_Pitzonka 9/14/2019 1:35pm
9/14/2019 1:35pm Edited Date/Time 9/14/2019 1:57pm
Blackjack31 wrote:
But why would the clutch make it harder? The clutch isn’t connected to the crank shaft.
It most definitely is unless you removed the primary gear from the crank...
Blackjack31
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Blackjack31 9/14/2019 3:33pm
9/14/2019 3:33pm
Blackjack31 wrote:
But why would the clutch make it harder? The clutch isn’t connected to the crank shaft.
Paul_Pitzonka wrote:
It most definitely is unless you removed the primary gear from the crank...
I did. It’s like when I kept adding weight onto the crank it would slowly get more resistance. When the cases put together, added a little resistance, when the primary drive gear was put on, a little more, stator, a little more, clutches, a little more. That’s why I think the crank itself is being pressed weird. That’s why I don’t think it’s the crankshaft being bent cause it’s not only the clutch but the clutch did add more. Also the crankshaft was rebuilt by one of the most respected motocross mechanics. I can get him to look over it again I guess.
TexasVet
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TexasVet 9/16/2019 7:29am
9/16/2019 7:29am
Been here. The bottom line is that SOMETHING IS WRONG! When assembled with just the crank in the cases, the

crank should(must be buttery smooth). Crank trueness(word?) and lots of other things. Heating the cases and freezing

the bearings is a must! Cock those bearings in the slightest, and you will score the bearing bore. Properly heated and

frozen(I'm not talking red hot)(if I know I'm going to do this at home, I put the bearings in the freezer overnight, wife

loves this!). Then heat the bearings and freeze the crank(repeat). The bearings should just drop right in their bores.

The crank assy. also. And if you are going to tap on the crank-put the nut on it! BTW-this is standard practice. Do all

of your "adjusting" while its hot/cold(ie quickly). If this were mine, STOP and investigate. Starting with the crankshaft

out. But then, there is always wrong parts, missing shims/washers on and on. Lastly, just because someone has a

"respected reputation" doesn't mean he can't make mistakes. Get ready to buy a new crank and bearings..at least.

No power tools should ever be used on a motorcycle. Nor anything other than a plastic mallet. Get an accurate torque

wrench. Do not do this without a shop manual.
sandman768
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sandman768 9/16/2019 12:37pm
9/16/2019 12:37pm
I had similar situation with an 87rm125 I rebuilt earlier this year. The crank was rebuilt and the web width was too wide, the factory manual list crank web min-max width, worth a check.
grimsypro 9/17/2019 2:57am
9/17/2019 2:57am
TexasVet wrote:
Been here. The bottom line is that SOMETHING IS WRONG! When assembled with just the crank in the cases, the crank should(must be buttery smooth). Crank...
Been here. The bottom line is that SOMETHING IS WRONG! When assembled with just the crank in the cases, the

crank should(must be buttery smooth). Crank trueness(word?) and lots of other things. Heating the cases and freezing

the bearings is a must! Cock those bearings in the slightest, and you will score the bearing bore. Properly heated and

frozen(I'm not talking red hot)(if I know I'm going to do this at home, I put the bearings in the freezer overnight, wife

loves this!). Then heat the bearings and freeze the crank(repeat). The bearings should just drop right in their bores.

The crank assy. also. And if you are going to tap on the crank-put the nut on it! BTW-this is standard practice. Do all

of your "adjusting" while its hot/cold(ie quickly). If this were mine, STOP and investigate. Starting with the crankshaft

out. But then, there is always wrong parts, missing shims/washers on and on. Lastly, just because someone has a

"respected reputation" doesn't mean he can't make mistakes. Get ready to buy a new crank and bearings..at least.

No power tools should ever be used on a motorcycle. Nor anything other than a plastic mallet. Get an accurate torque

wrench. Do not do this without a shop manual.
That was hard to read
2
kb228
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kb228 9/17/2019 5:09am
9/17/2019 5:09am
TexasVet wrote:
Been here. The bottom line is that SOMETHING IS WRONG! When assembled with just the crank in the cases, the crank should(must be buttery smooth). Crank...
Been here. The bottom line is that SOMETHING IS WRONG! When assembled with just the crank in the cases, the

crank should(must be buttery smooth). Crank trueness(word?) and lots of other things. Heating the cases and freezing

the bearings is a must! Cock those bearings in the slightest, and you will score the bearing bore. Properly heated and

frozen(I'm not talking red hot)(if I know I'm going to do this at home, I put the bearings in the freezer overnight, wife

loves this!). Then heat the bearings and freeze the crank(repeat). The bearings should just drop right in their bores.

The crank assy. also. And if you are going to tap on the crank-put the nut on it! BTW-this is standard practice. Do all

of your "adjusting" while its hot/cold(ie quickly). If this were mine, STOP and investigate. Starting with the crankshaft

out. But then, there is always wrong parts, missing shims/washers on and on. Lastly, just because someone has a

"respected reputation" doesn't mean he can't make mistakes. Get ready to buy a new crank and bearings..at least.

No power tools should ever be used on a motorcycle. Nor anything other than a plastic mallet. Get an accurate torque

wrench. Do not do this without a shop manual.
grimsypro wrote:
That was hard to read
X100
krgperformance
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krgperformance 9/17/2019 8:53am
9/17/2019 8:53am
since crank was rebuild 100 percent check the run out making sure its .001 or under run out
and check the over all width maybe the crank is to wide and the cases is hanging it up making the crank hard to roll over

TexasVet
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TexasVet 9/18/2019 6:03pm
9/18/2019 6:03pm
TexasVet wrote:
Been here. The bottom line is that SOMETHING IS WRONG! When assembled with just the crank in the cases, the crank should(must be buttery smooth). Crank...
Been here. The bottom line is that SOMETHING IS WRONG! When assembled with just the crank in the cases, the

crank should(must be buttery smooth). Crank trueness(word?) and lots of other things. Heating the cases and freezing

the bearings is a must! Cock those bearings in the slightest, and you will score the bearing bore. Properly heated and

frozen(I'm not talking red hot)(if I know I'm going to do this at home, I put the bearings in the freezer overnight, wife

loves this!). Then heat the bearings and freeze the crank(repeat). The bearings should just drop right in their bores.

The crank assy. also. And if you are going to tap on the crank-put the nut on it! BTW-this is standard practice. Do all

of your "adjusting" while its hot/cold(ie quickly). If this were mine, STOP and investigate. Starting with the crankshaft

out. But then, there is always wrong parts, missing shims/washers on and on. Lastly, just because someone has a

"respected reputation" doesn't mean he can't make mistakes. Get ready to buy a new crank and bearings..at least.

No power tools should ever be used on a motorcycle. Nor anything other than a plastic mallet. Get an accurate torque

wrench. Do not do this without a shop manual.
grimsypro wrote:
That was hard to read
kb228 wrote:
X100
Ok. To the OP-

Stop.

Take your motor to a QUALIFIED MECHANIC.

You are out of your depth.

Better?
2

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