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Thread: '86 250R refurbish

  1. #46
    Join Date
    Apr 2017
    Location
    Wausau Wi
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    116
    Quote Originally Posted by Red Rider View Post
    Yep, I agree. Every time I see these, I forget that the price is only for 1 roller. $25 for the set would be an honest price, and would still make them a nice profit I bet. Be sure to post pics of your fabwork.
    Welp I didn't have any scrap the right size in the shop for UHMW so I had to break down and order some. But the bearings and the material came out to $16 bucks. Should net me around 5 rollers. Stuff should be in Friday so probably a next monday/Tuesday job. The 1.375 comes out yo 34.925 OD, my target was 34-35 this should fit the bill and remove an OP. Anyway here are some crusty shop notes (for posterity) since I didn't have one to measure. The second picture is the bearing sitting on a socket that is the target diameter of the outer shoulder, I was just playing with ratios and proportions.



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  2. #47
    Join Date
    Apr 2017
    Location
    Wausau Wi
    --
    116
    In the down time the real fun has started... I know the the pictures don't show the best but these is the before shots. The standing has begun, we made it to 400 grit tonight before I had to pick my arm up off the floor. I'm not looking for perfect, just trying to knock down the mountains and smooth out the craters.

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  3. #48
    Join Date
    Apr 2017
    Location
    Wausau Wi
    --
    116
    I took the fender up to 1500 grit tonight. (First 3 pictures) Plastic was, for the most part, as smooth as Steve McQueen. 4th picture is about 10 minutes into the left side. And finally the last picture was about 20 minutes of polishing, still have some work but it's coming along.

    In other news, the bearings and UHMW rod came in so I might be able to squeeze out some bearings tomorrow afternoon.




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  4. #49
    Join Date
    Jul 2011
    Location
    Colorado
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    141
    How does the UHMW material compare to delrin?

  5. #50
    Join Date
    Apr 2017
    Location
    Wausau Wi
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    116
    Quote Originally Posted by Stingray View Post
    How does the UHMW material compare to delrin?
    That is a slightly loaded question as it depends on what you are looking for.

    Delrin is a much more stable and easy machining material. It wont cold flow and will maintain precision tolerances much better than UHMW.

    UHMW (ultra high molecular weight polyethylene) is a very dense, hence high molecular weight, plastic which makes it very good, better than delrin, at impact and abrasion loading. Though it is a bear to machine and is known to cold flow it's not the best choice for high precision tolerances. It is also half the cost of delrin.

    So neither is better over all, just situationally better. And the shock, impact, and abrasion loading advantages are why I went UHMW for this application.

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  6. #51
    Join Date
    May 2006
    Location
    The Open Road
    --
    4,729
    Quote Originally Posted by Kamnahrt View Post
    ... Though it is a bear to machine and is known to cold flow it's not the best choice for high precision tolerances. It is also half the cost of delrin...
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    That's putting it lightly.

    I don't care how you hold it down, UHMW is incapable of being machined in perfectly parallel or square sides. That stuff defies all the laws of physics and geometry both. And the bigger the piece, the worse your results, speaking in a precision tolerance sense.

    (Sarcasm) I swear you'd be just as successful ing it into the desired shape as cutting it

    Can you tell I had to mill a bunch of it just last week? I can't remember being that frustrated except the last time I turned a bunch of Inconel for a month



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  7. #52
    Join Date
    Apr 2017
    Location
    Wausau Wi
    --
    116
    Quote Originally Posted by ironchop View Post
    That's putting it lightly.

    I don't care how you hold it down, UHMW is incapable of being machined in perfectly parallel or square sides. That stuff defies all the laws of physics and geometry both. And the bigger the piece, the worse your results, speaking in a precision tolerance sense.

    (Sarcasm) I swear you'd be just as successful ing it into the desired shape as cutting it

    Can you tell I had to mill a bunch of it just last week? I can't remember being that frustrated except the last time I turned a bunch of Inconel for a month



    Sent from my Z958 using Tapatalk
    Well I might have down played its wonderful machinability which is not unlike pushing a rope. Also, my condolences to you patience for having to dick with that stuff for a week. I have never had to turn any inconel but if its any like titanium I feel your pain!

  8. #53
    Join Date
    Apr 2017
    Location
    Wausau Wi
    --
    116
    Had some time to sneak out to the shop today while the boys were at lunch. I still need to deburr some of the fuzz off but I ran out of time. Il admit not as pretty as the $25 ones but they should hold a chain.



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  9. #54
    Join Date
    May 2006
    Location
    The Open Road
    --
    4,729
    They'll be dirtier five minutes after you drag a chain across them anyway

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  10. #55
    82 250r's Avatar
    82 250r is offline At The Back Of The Pack Arm chair racerAt the back of the pack
    Join Date
    Mar 2007
    Location
    Utah
    --
    278
    Looking at your sanded fenders gives me flashbacks. Took me 5 days to sand mine to 1500.
    It was well worth it...they still look good 5 years later.

    Your build looks awesome!
    Marc

  11. #56
    Join Date
    Apr 2017
    Location
    Wausau Wi
    --
    116
    The project had been on a slight hold recently. The porter was slammed so it took a little long than expected but I finally have the top end back. The head has been decked .010, a mid range port and re bore to the next piston size ( 68mm). Next to blast and powder to get it back to the year correct silver.



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  12. #57
    Join Date
    Jun 2010
    Location
    House Springs MO
    --
    5,496
    I looked into doing chain rollers back when I started with the delrin bushings. I even bought the bearings and bits to make it work, but never got around to it. Your project looks great keep it up.

  13. #58
    Join Date
    Apr 2017
    Location
    Wausau Wi
    --
    116
    Quote Originally Posted by bkm View Post
    I looked into doing chain rollers back when I started with the delrin bushings. I even bought the bearings and bits to make it work, but never got around to it. Your project looks great keep it up.
    Thank you sir, they weren't bad at all 15 minutes in the lathe and you're pressing in bearings.

    I know this isn't R related but hey it's my party il cry if I want to. Here are some pics of the ol big red getting a hot supper this weekend. Clearing some paths through the back 40 and setting up some food plots.



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  14. #59
    Join Date
    Apr 2017
    Location
    Wausau Wi
    --
    116
    Well gentlemen I called away on work for the past 3 weeks out of country so there hasn't been a lot of progress. I had a couple presents awaiting me when I got back. A new rotating assembly from hot rods, I do enjoy there packaging. All of the bearings and seals are en route and lastly got to throw the cases into the blaster tonight and hoping to put her in the wash tank tomorrow.

    The only thing I need now is a new countershaft retainer/timing holder. I do have a question for the masses about the adjustable timing retainer. Is it worth the extra 20 bones to add that feature to be able to find tune the timing in? Do these bikes respond well to timing changes?

    Thank you guys for looking and the input!



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  15. #60
    Join Date
    Jan 2012
    Location
    Carthage NY 250r rules
    --
    2,345
    When your ready to install your crank put it the freezer night before and heat your crank bearing it will slip right in.The hot rod cranks are press fit .
    250r rules

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