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rebuilding a crank


too_fazt

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I just got a roller with a busted engine and the crank is in pretty bad shape. i have a crank leftover from my previous build..it spins fine but could use a freshening up. iv never messed with a crank before...would it be better to just buy a used one? any insight would be great.

Edited by too_fazt
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I just got a roller with a busted engine and the crank is in pretty bad shape. i have a crank leftover from my previous build..it spins fine but could use a freshening up. iv never messed with a crank before...would it be better to just buy a used one? any insight would be great.

I would not put a used crank in my engine. There is no way to tell if it will last 15 minutes or 15 years. As far as rebuilding it, do you have a press, bearing seperator and the jigs needed to get it apart and back together again? And then you need the V blocks and dial indicator to get it in phase and running true and then a TIG welder to weld it up once everything is perfect. I have been using Twister for the last few cranks in my bikes and my friends bikes that I work on. The crank that is in my personal bike I got to watch Twister build it completly from scratch because it wasn't done when I went to pick it up, so I saw first hand how it was done and I know it was done right because I stood there and watched every step and saw all the dial indicator readings. It wasn't that I doubted their work, I just wanted to see how it was done. They made it look easy, but I wouldn't try it myself and I have everything I need to do it except the welder. Just my .02.

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exactly, i would not hesitate buying a used crank though from someone reputable on the site such as NYUK if they know the amount of hours on the bike, i would then send the crank out to a builder and have them true and weld it and give it a once over. If the outer bearings and the rod bearings are good then there should not be to much of the problem.

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As far as rebuilding a crank goes, I've done it. Not on a banshee, but on a YZ490. It's a pain in the butt for all that it is. It's just you can't get remanufactured 490 cranks that easily. Price wise though, if you put all new bearings, cheapest you can find, and new crank pin and big end bearings and rod you will have almost as much in a stock crank and stil have all the labor as you would in a remanufactured unit from wiseco or hotrods. I'm not afraid of a used crank if it specs out right. You'll need a feeler gauge and dial indicator to check your tollerances and something to set the crank on to check it's run-out values. The values for crank spec can be found in the banshee manual posted under "useful links" at the top of the mod/repair forum. I am going to use a used crank in my machine, i paid 210 for a stroker crank shipped to my door from ebay from a reputable seller and then checked it's specs when i got it. It speced on the tight side of the specification tolerances so I'm thinkin I should be good. That's just my cheap ass 2cents though.

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As far as rebuilding a crank goes, I've done it. Not on a banshee, but on a YZ490. It's a pain in the butt for all that it is. It's just you can't get remanufactured 490 cranks that easily. Price wise though, if you put all new bearings, cheapest you can find, and new crank pin and big end bearings and rod you will have almost as much in a stock crank and stil have all the labor as you would in a remanufactured unit from wiseco or hotrods. I'm not afraid of a used crank if it specs out right. You'll need a feeler gauge and dial indicator to check your tollerances and something to set the crank on to check it's run-out values. The values for crank spec can be found in the banshee manual posted under "useful links" at the top of the mod/repair forum. I am going to use a used crank in my machine, i paid 210 for a stroker crank shipped to my door from ebay from a reputable seller and then checked it's specs when i got it. It speced on the tight side of the specification tolerances so I'm thinkin I should be good. That's just my cheap ass 2cents though.

You can't replace the pin in a stock Banshee crank. it is cast as part of the web and then machined. The only way to replace it is to machine it out with a mill and then you need to come up with a pin.

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I did not know that. I do know you can get crank pins with the rod rebuild kits. http://www.denniskirk.com/jsp/product_catalog/Product.jsp?skuId=CR178&store=Main&catId=&productId=p147893&leafCatId=&mmyId=3165

 

But i've never dealt with pullin a banshee crank apart, just my YZ and specing banshee cranks. No to thread jack so the reason to weld the cranks on banshees is just to keep those outter webs from spinning? I assumed it was from the fact of how hard it would be to ballance a bazillion piece crank LOL.

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I did not know that. I do know you can get crank pins with the rod rebuild kits. http://www.denniskirk.com/jsp/product_catalog/Product.jsp?skuId=CR178&store=Main&catId=&productId=p147893&leafCatId=&mmyId=3165

 

But i've never dealt with pullin a banshee crank apart, just my YZ and specing banshee cranks. No to thread jack so the reason to weld the cranks on banshees is just to keep those outter webs from spinning? I assumed it was from the fact of how hard it would be to ballance a bazillion piece crank LOL.

 

Why is it that you are rebuilding the crank? I am buying a shee this weekend that the kid says will need a new top end and possibly a crank bearing, should I be weary? I have done a top end before in a previous shee, but Im like you, and have never screwed around with the crank!

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just buy a new crank their easy to put in just get a clymers, ive done top ends before but i was worried about the crankjob i had to do but man its cake, the shee motor splits top and bottom, so easy to do i just finished mine and it runs great, all new top to bottom

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