Pulling Crankshaft/bottom end out of YZ250F.. Do I need this special tool?


8 replies to this topic
  • freebs

Posted August 05, 2009 - 09:49 PM

#1

Just got my service manual and I am looking up how to pull out the crank as I need to replace it, but it calls for a special puller tool to pull it out. Now I have built a number of automotive engines before where they call for special tools and you really don’t need them. Is this one of thoughts cases? Or am I going to need to need this tool?

From what I can see, it is just 2 bolts that are mounted to a plate that thread into holes inside the case, than a center bolt that goes between the other two and threw the plate either pulls or pushes the crank out... kind of like a pulley puller

  • melon16

Posted August 05, 2009 - 10:38 PM

#2

the only tool you need is the puller for the flywheel--a couple taps on the end of the crank with something to prevent damage to the crank in between and it comes out easily.

i just replaced the connecting rod/lower bearing/pin on my 06wr250fv

  • freebs

Posted August 05, 2009 - 11:15 PM

#3

the only tool you need is the puller for the flywheel--a couple taps on the end of the crank with something to prevent damage to the crank in between and it comes out easily.

i just replaced the connecting rod/lower bearing/pin on my 06wr250fv


thats what I thought, but it says do not use a hammer in the book, so I wasnt sure if there was another reason for it or not.

well looks like I will just pull out the hammer and block of wood to get the job done

And if the flywheel is anything like on my buddies Kawi 2 stroke... Just a regular pulley puller to pull it off and a light touch on the impact gun to get it on and its done

  • MartyMOOSE

Posted August 06, 2009 - 05:25 AM

#4

thats what I thought, but it says do not use a hammer in the book, so I wasnt sure if there was another reason for it or not.

well looks like I will just pull out the hammer and block of wood to get the job done

And if the flywheel is anything like on my buddies Kawi 2 stroke... Just a regular pulley puller to pull it off and a light touch on the impact gun to get it on and its done


Put the flywheel on before you fit the outer RHS side case and you can jam up the primary gears with a piece of alloy and tension it. The rattle gun method is not real good for a flywheel IMHO.

MM

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  • freebs

Posted August 06, 2009 - 10:26 AM

#5

Put the flywheel on before you fit the outer RHS side case and you can jam up the primary gears with a piece of alloy and tension it. The rattle gun method is not real good for a flywheel IMHO.

MM


I just use it to suck the flywheel on... than I back the nut off and torque it on properly. But this way I know the flywheel is pressed on as far as it can go.

  • mkporn

Posted August 06, 2009 - 12:35 PM

#6

I just use it to suck the flywheel on... than I back the nut off and torque it on properly. But this way I know the flywheel is pressed on as far as it can go.



Be careful with the impact on the flywheel. The threads on the crank are pretty soft and are very easy to pull.....They will strip easy and you will be pulling it back apart to either tap the end of the crank for a stud or replace it all together.......Trust me, a 3/8" butterfly has enough torque to spin the threads.....:thumbsup:

  • freebs

Posted August 06, 2009 - 02:33 PM

#7

Be careful with the impact on the flywheel. The threads on the crank are pretty soft and are very easy to pull.....They will strip easy and you will be pulling it back apart to either tap the end of the crank for a stud or replace it all together.......Trust me, a 3/8" butterfly has enough torque to spin the threads.....:thumbsup:


:worthy: thanks for the heads up, I will see if I can find another way to have the flywheel pressed on rather than using the threads to do this

  • mkporn

Posted August 07, 2009 - 05:34 AM

#8

It's on a tapered shaft, there is no reason to press it on. The fly wheel will go right on and just tightening the nut to the right amount is enough to get it where it needs to be. Unless the end of the crank has nicks on it, the fly wheel will pop on perfectly. The nut is simply holding it in place and the torque on it is to hold the nut firm, the nut simply is there to keep the flywheel seated, I have ran a bike with a piece of hose shoved over the threads to hold the flywheel on (quick trail fix for someone that was not exactly paying attention to how they put their bike together).....

As for pulling it, just go buy a $20 internal puller, the correct on fits a ton of bikes and if you do much bike work you will use it again and again, it's worth it to just buy it and forgo terying to use a regular puller with fingers...

  • freebs

Posted August 07, 2009 - 07:53 PM

#9

It's on a tapered shaft, there is no reason to press it on. The fly wheel will go right on and just tightening the nut to the right amount is enough to get it where it needs to be. Unless the end of the crank has nicks on it, the fly wheel will pop on perfectly. The nut is simply holding it in place and the torque on it is to hold the nut firm, the nut simply is there to keep the flywheel seated, I have ran a bike with a piece of hose shoved over the threads to hold the flywheel on (quick trail fix for someone that was not exactly paying attention to how they put their bike together).....

As for pulling it, just go buy a $20 internal puller, the correct on fits a ton of bikes and if you do much bike work you will use it again and again, it's worth it to just buy it and forgo terying to use a regular puller with fingers...


Yea I saw a cheap puller at the local bike shop I was thinking of picking up.

But speaking of pullers, I was watching a youtube video for pulling apart and rebuilding the bottom end, and it defiantly looks like I am going to need this special puller for the crank. Not so much to get the old one out, but to basically press the new crank assembly in. It looks like tapping it out with a rubber mallet will work but putting it in is going to be hard and possibly ruin something by tapping it back in... Anyone have experience tapping it back in?

Also if you have pulled the entire case apart, how hard it is to get the transmission gears back in? In the video they say it is fairly difficult to get back in. My worry is things springing apart and being an absolutely pain to get back in… ahah I may built LS7’s corvette engines and other 800+hp engines but when it comes to transmissions.. AHHHH ahah they are my biggest fear and I always hand that off to someone else …




 
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