Need advice on crank install Yz250f

black-smoker
So I'm about to put the cases together, but one thing that has stuck on my mind is that the crank
don't slip in to the new bearings with ease (the old ones did). I made a puller and pushed the crank in to one side, but if i do the same on the other side while putting the cases together i can't tell if there is tension "sideways " in the bearings if you know what i mean? maybe I'm just over thinking this, and the tension will settle when the engine warms up?
Or should i heat up the inner ring of the bearing and quickly push the cases together?

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Paw Paw 271
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Paw Paw 271 3/27/2017 2:26pm
3/27/2017 2:26pm Edited Date/Time 3/27/2017 2:27pm
A few heat cycles will correct that. Be sure to have the new crank checked for run out before you install it. I have seen many new cranks come out of the box out of true and cause early failure.

Paw Paw
pete24
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pete24 3/27/2017 3:37pm
3/27/2017 3:37pm
a buzzard taught me a long time ago to measure the space between the cases and side of crank with a feeler gauge, and tap it over, till its centered with a lead hammer, this also seats the crank in the bearings
TAP it squarely, dont whale the piss out of it
BobPA
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BobPA 3/27/2017 7:36pm
3/27/2017 7:36pm
Put the crank in the freezer over night, should drop right in
black-smoker 3/28/2017 1:14am
3/28/2017 1:14am
Paw Paw 271 wrote:
A few heat cycles will correct that. Be sure to have the new crank checked for run out before you install it. I have seen many...
A few heat cycles will correct that. Be sure to have the new crank checked for run out before you install it. I have seen many new cranks come out of the box out of true and cause early failure.

Paw Paw
By heat cycles, do you mean running the engine to operating temperature? If so, I was thinking that to, the bearings will self-align.

The Shop

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black-smoker 3/28/2017 1:16am
3/28/2017 1:16am
pete24 wrote:
a buzzard taught me a long time ago to measure the space between the cases and side of crank with a feeler gauge, and tap it...
a buzzard taught me a long time ago to measure the space between the cases and side of crank with a feeler gauge, and tap it over, till its centered with a lead hammer, this also seats the crank in the bearings
TAP it squarely, dont whale the piss out of it
That is also something to consider, getting the crank centered.
harescrambled
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harescrambled 3/28/2017 2:11pm
3/28/2017 2:11pm
BobPA wrote:
Put the crank in the freezer over night, should drop right in
That's how I do it...I freeze the crank overnight, and it just slips right into the bearing. I drop the primary gear side in first, then use a crank installation tool to do the flywheel side
Rockinar
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Rockinar 3/28/2017 5:00pm
3/28/2017 5:00pm
I just did a Honda 2 stroke with Honda bearings and factory crank. It pretty much slid right in on the tranny side with no need for freezing or heating anything. Have not closed the case so I don't know about the other side.
adam8781
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adam8781 3/29/2017 10:34am
3/29/2017 10:34am
heat the bearing race with a heat gun and drop the crank into the right side case first, than heat the bearing race on the left side case and bolt it together.

once the bearing race is hot enough to sizzle off water you are good togo, i dont use a torch its easy to overheat the race and mess up balls from excessive pressure when the race expands.

Dozens of engines through my shop in the last few months, i never use a crank install tool this method never fails me
black-smoker 3/30/2017 10:20am
3/30/2017 10:20am
Thanks everyone for your inputs, I got it sorted by cleaning the bearing from some sort of protective wax. It slipped nice and firmly together after that.


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