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Crank Installation Method

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I'm going to be installing my new crank in the next week or so and just wondered what method you guys use when getting the cases back together. I have it clear in my mind how the main bearings are going to go in (cases in oven, bearings in freezer) I'm just not totally clear on pulling the crank into the bearings. I thought about just using the case bolts to pull it all in but I expect that this will put undue stress on the big end bearing and may cause misalignment/premature failure?

 

I've also seen the Tusk tool that can be used to pull the crankshaft in one side at a time. This seems like a good way to go but we don't seem to have those tools over here. Any help on alternative methods to achieve the same result as this tool without using it would be greatly appreciated. I'm thinking maybe some kind of plate and using nuts/washers?

 

Thanks in advance,

 

Jim 

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Just put the crank in the freezer for at least 24hrs. Now place a slug over the inner race of the main bearings and heat with a torch. Crank drops right in first side. Quickly heat the main bearing of the second case the same way and drop on. When done properly it all falls together with no force. Much better method than a crank puller IMO.

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Just put the crank in the freezer for at least 24hrs. Now place a slug over the inner race of the main bearings and heat with a torch. Crank drops right in first side. Quickly heat the main bearing of the second case the same way and drop on. When done properly it all falls together with no force. Much better method than a crank puller IMO.

 

I have done it this was twice now.  But you don't need to put the crank in the freezer, room temperature works.

 

I would suggest practicing with your old crank and bearings to get a feel how to do it.

Edited by H-B-R

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Just put the crank in the freezer for at least 24hrs. Now place a slug over the inner race of the main bearings and heat with a torch. Crank drops right in first side. Quickly heat the main bearing of the second case the same way and drop on. When done properly it all falls together with no force. Much better method than a crank puller IMO.

No problem with a crank puller, both methods about equal.

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Just Google homemade 2 stroke crankshaft puller and choose images. They are really easy to make

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Crank puller here.  I would be really afraid of an expensive mistake without one.  Are you sure they are not available in the UK?

 

I would like to try the heat method sometime, but (fortunately)I very rarely have to deal with crank or transmission problems.  

Edited by rpt50

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Thanks for the input guys, I think I'm gonna give the heated slug method a go, it sounds pretty good to me, providing that I can find a slug the right size that is!

There probably are pullers available in the UK but I haven't seen any so far. Only the tusk ones from the US.

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Thanks for the input guys, I think I'm gonna give the heated slug method a go, it sounds pretty good to me, providing that I can find a slug the right size that is!

 

Are you rebuilding your old crank or getting a new one?

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I was asking because you can use 1/2 of your old crank as your slug.  You just have to grind down the part that fits inside the bearing a little, this is what I use:

 

cank-slug-install-1.jpg

 

 

cank-slug-install-3.jpg

 

I've read where people have used sockets, but there is so little mass there that it might cool off too quickly.  This stays hot for a long time.

Edited by H-B-R
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I was asking because you can use 1/2 of your old crank as your slug.  You just have to grind down the part that fits inside the bearing a little, this is what I use:

 

cank-slug-install-1.jpg

 

 

cank-slug-install-3.jpg

 

I've read where people have used sockets, but there is so little mass there that it might cool off too quickly.  This stays hot for a long time.

 

 

That is way over complicating things. All you need is a socket or a bearing driver plate placed on top of the inner race.

I like using a bearing driver plate

 

 

https://www.google.ca/search?q=bearing+driver+set&espv=2&tbm=isch&imgil=R8iRDsO9txOjaM%253A%253BVcIO1q9tHqTr3M%253Bhttp%25253A%25252F%25252Fwww.oreillyauto.com%25252Fsite%25252Fc%25252Fdetail%25252FLIS0%25252F59400%25252FN2354.oap%25253Fck%2525253DSearch_N2354_-1_-1%25252526pt%2525253DN2354%25252526ppt%2525253DC0374&source=iu&usg=__5NG-NrpcomCT5cx3WBEmHpSoHz4%3D&sa=X&ei=-3frU8foJ8fsoATk_IL

 

I have done dozens of bottom ends this way. And I personally would not skip the crank in the freezer. Again why make things harder than they need to be.

KISS

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I have done dozens of bottom ends this way. And I personally would not skip the crank in the freezer. Again why make things harder than they need to be.

KISS

How do you get rid of the condensation on the crank and big end bearing?

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How do you get rid of the condensation on the crank and big end bearing?

 

 

A little 2 stroke oil and call it good. Never found it to be an issue.

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How do you get rid of the condensation on the crank and big end bearing?

Put petroleum jelly on the bearing before it goes into the freezer, it'll keep the moisture off of it and will just burn up and go away when you start he bike

Came from ken o'connor in one of this crank rebuild videos (the fact it'll just burn up on combustion, not the idea to put it on before the freezer)

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Came from ken o'connor in one of this crank rebuild videos (the fact it'll just burn up on combustion, not the idea to put it on before the freezer)

 

Yep, his videos are what got me doing it that way.  His "slug" looked pretty hefty, so I figured I needed something with some mass to it.

 

I can see where having the crank cold would help, but based on the condensation that forms on the bearings when you take them out of the freezer, I didn't want to have to deal with that on the crank.  As soon as I get the bearing in the case, I pop the whole thing back in the oven for a few minutes to warm up and dry out the bearing.  I wasn't about to stick the entire engine in the oven.

 

And yes, I over-complicate everything I do.

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Yep, his videos are what got me doing it that way.  His "slug" looked pretty hefty, so I figured I needed something with some mass to it.

 

I can see where having the crank cold would help, but based on the condensation that forms on the bearings when you take them out of the freezer, I didn't want to have to deal with that on the crank.  As soon as I get the bearing in the case, I pop the whole thing back in the oven for a few minutes to warm up and dry out the bearing.  I wasn't about to stick the entire engine in the oven.

 

And yes, I over-complicate everything I do.

 

 

I just gave a solution to the condensation hahaha

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Thanks again for all your help folks! I've got it all back together now and will be firing her up at the weekend. With the fresh cylinder, crank and piston it should be good. I was just wondering before I do if anyone does any checks for crank alignment with the cases and cylinder after a rebuild? Cheers, Jim

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Using the 'hot slug' method. It took a tap to centralise after the cases were completely together though. Went with a bit of a pop. I checked the gaps each side between the crank and the cases and they were within 0.1-0.2mm of each other.

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