Advice on an RD 250 build

Discussion in '2 smokers' started by sprouty115, Dec 1, 2012.

  1. sprouty115

    sprouty115 Long timer

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    OK, so I just got back from the dealer and this is what I found:
    - The bike was torn down to the point where the mufflers, cylinder heads, cylinders, pistons, left and right covers, and the clutch were all off.
    - The pistons and cylinders both had slight scoring so it definitely could use a top end.
    - The stator was still on but I could hear a loud clunk with each revolution of the crank. I'm not sure exactly how they determined it was bad but there is something going on there.
    - The "bent crank" was supposedly on the clutch-side, but there was no visible run-out and no indicator to confirm anything.

    We discussed the bike, and the gist of the conversation was that they would prefer that I source all the parts and deliver them, then they do the work. Of course the follow-up to that was - "but remember it's a really old bike and anything could go wrong..." It turns out the $2K figure was simply a swag to see if I was really interested in having them work on it. It wasn't based on specific parts or labor. Oh well, live and learn.

    I told them to put it all back together and I'd be back to pick the bike up next week. The bottom line is they must have had over 60 bikes lined up for service and this didn't strike me as something they do often or were particularly excited about getting involved with.

    So back to the house it goes. I'll take a look at it and sort it out even though I really don't have time to tear it apart unless I get a reprieve on the two projects ahead of it. Definitely too clean to sell and I can't bear to part it out. Might be time to have a discussion with my son.

    BTW, thanks for all the advice. I think I was initially expecting feedback that basically said suck it up, that's what it costs. So thanks for the different perspectives, especially the idea that this may not be the right first-bike.
    #21
  2. markjenn

    markjenn Long timer

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    I think you're doing the right thing. Working on an old bike like this is a very specialized activity and you need to find the right old-timer to assist you. They're out there, but you have to ferret them out.

    Take the $2K you were planning on spending to fix it up and find a more modern bike for your son. Put the RD250 in your garage and start working through the problems one-by-one on your own and on a relaxed schedule. Whether you do the work yourself or take assemblies and farm them out, you'll find that there are literally hundreds of folks on the net who know of specialized shops and individuals who will help you through the process, including many right here. It will be fun. The RD250 is a good bike with a lot of interest and none of the systems are complex or intractable. And it will be worth enough when you're done that you're not going to be pouring money down the drain.

    - Mark
    #22
  3. stainlesscycle

    stainlesscycle Long timer

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    that's the line where i would grab my parts and go. sure there could be issues in there, but nothing really that costly....i wouldn't have 'em put it back together though - they've done half the job for you......


    you're doing the right thing. take your time, and build the motor, farm out the crank job, hell even farm out everything - you'll see 2k could build you a pretty stellar motor. .there are some very good engine builders around if you want to send it out.
    #23
  4. Moonshiner

    Moonshiner aka "B-dog"

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    Yep, I don't think they wanted to work very badly on the little RD. They were trying to talk you out of it.

    You did the right thing.

    Another good forum for 2 stroke support is USA2strokers.com. That's in addition to HERE of course...
    #24
  5. Edmond Dantès

    Edmond Dantès The Kanto Pain

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    It would be ace if you and your son worked on the bike together.
    #25
  6. anonny

    anonny What could go wrong?

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    I agree with the masses, go and pick it up in the state it's in and make it a project for you and your son. He needs to learn how a motor works and we all need to spend time with our children.

    Rebuilding a two stroke is not that big of a task, and I'm not buying the bent crank without putting a dial gauge on it.
    #26
  7. sprouty115

    sprouty115 Long timer

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    Yeah that's the plan at this point. Sort of worked it out with my better-half: grab the bike next week and show it to him at Christmas break. If he digs it, and truthfully I bet he will, then we tear it apart together. I'll send whatever needs work out and collect all the rest of the gaskets, bearings, etc. Then plan a weekend or three when he can get back home and we can put it all back together. Then as time permits we can go through the rest of it.

    The worst that can happen is that he's not into the idea and commitment of an old bike (and I'm fine with that), so I sort out another option for him and end up with a cool RD.

    Also thanks for the links. I've looking around and found this: http://www.aircooledrdclub.com/smf/index.php?topic=25398.0
    #27
  8. stainlesscycle

    stainlesscycle Long timer

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    #28
  9. mtothef

    mtothef Been here awhile

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    #29
  10. Shocktower

    Shocktower Long timer

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    You need to post a video of the ecited boy with the new to him 2 stroke bike, BTW if he's not happy I'll be your son self supporting and we can do the bike together :roflDad :lol3
    #30
  11. sprouty115

    sprouty115 Long timer

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    Just a quick update: We showed the bike to my son on Christmas day and he was definitely very happy about it. But I also discussed in detail the work that would be required, both to get it back on the road and to kep it running. He definitely took the conversation seriously and we agreed to discuss it further after he had some time to think about it.

    In the meantime we both decided the bike was worth getting road worthy so we dug a little deeper into the engine to see exactly what was going on. So after all the presents were opened we snuck back out to the shed and here is what we found:

    • We pulled the clutch-side case and primary drive gear and then and measured the crank run-out. It showed .007 TIR. OK, so the crank needs to be re-built.
    • Then we yanked the engine (took about an hour) and brought it into the basement to be able to work on it on a proper bench with better light and with some heat.
    • The first thing I noticed was that the screws and bolts indicate that the bike has been worked on. Most of the phillips heads are pretty beat up and others have been replaced with hex-head bolts.
    • Next, we pulled the heads and cyclinders and I showed him where the scoring was. They'll get cleaned and sent out soon too.
    At that point we were sort of running out of time so we figured we'd call it quits. Then an odd thing happened - as I was moving the engine around I tipped it up slightly onto the clutch-side and out of somewhere rolled a single stainless ball bearing about .25" in diameter? The cases weren't split yet so this sort of surprised me.

    Anyway now I'm into it and looking for a way to keep my son updated so he can follow along (the idea of us doing the work together won't really work for now). I may start a build thread or post it to a blog or maybe just keep this thread going? (thoughts anyone?).
    #31
  12. bykpimp

    bykpimp Live and let ride

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    I believe that ball bearing goes on the end of the clutch push rod shaft.
    #32
  13. sprouty115

    sprouty115 Long timer

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    Excellent, thanks.
    #33
  14. markjenn

    markjenn Long timer

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    I'd suggest you just post here. You already have a following.

    I like your approach. Do the minimum to get it mechanically sound and running and don't worry about the cosmetics. Way too many folks start by tearing the bike down to the last nut/bolt and money on paint and polish. Most lost interest and the project becomes a basket case. Get it running and on the road.

    - Mark
    #34
  15. sprouty115

    sprouty115 Long timer

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    Actually that's a good point, and I also could use the help the deeper it gets. I'll send him a link and have him join in.
    [​IMG]


    OK, I've got the case split and here is what I've found so far...
    [​IMG]



    Crankshaft - This thing is definitely whacked. The primary side actually has .010" TIR; the stator-side has .027"; the web/counter-balancer(s) show visible wobble (left/right). Heck there are even some jaw marks where someone clamped the crank in a vice! I've already sent an email to Lyn Garland at Vintage Specialties and he gave me pricing for a rebuild (around $600). But I think I'll email him back and see what his concern level is about the condition of the crank. I do have a local option for a used crank and stator for $120, which should be in better condition than what I have.


    (vice marks in web - also note how the bearing wasn't positioned/rotated correctly by the person that did the last tear-down, the raised dot is supposed to mate with machined notches that are in the front where the cases meet)
    [​IMG]



    (points cam with deep pits)
    [​IMG]



    Pistons - they both show signs of scuffing but there is no damage to be concerned about. They also measure 2.116" (53.76mm). I believe this is the stock size, even though one of them has #5 next to the arrow on the piston crown. The cylinder bores also show some slight scuffing and measure 2.128" (50.05mm). I plan on doing the top end too and Lyn Garland recommended Bore Tech in Ohio, so I sent an email off to them for some info and pricing.

    (piston top - cleaned up a bit with a wire brush)
    [​IMG]

    (piston side)
    [​IMG]



    Obviously I wasn't expecting this from a bike that is supposed to have only 6K miles on it, especially since the rest of the bike is so clean. Oh, well...next up cleaning the cases and more inspection.
    #35
  16. lrutt

    lrutt SILENCE.....i kill you

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    pistons actually look fairly normal for those miles, what does the cylinder look like.

    That price for a rebuilt crank is pretty good. Just make sure the tack weld it up after pressing together so it will stay put. for all that work, I'd get the crank rebuilt vs used. At least you'll know EXACTLY what you have. Stator should be easy to source.

    You could always buy a used motor/bike and have all the spare parts you need. Chances are you'd only need a top end job then. Just a thought.

    Don't scrimp on that bottom end though, and make sure you have a reputable shop do the bore job. Personally I'd stick with stock pistons and go with the recommended clearances vs Wiseco forged with larger clearances. Wisecos will rattle more and unless you plan on racing, the stockers will work just fine. Do a good job of testing your autoluber just to make sure it's working, then properly bleed it when you get it back together. Run synthetic 2 stroke oil.

    I just got my little Suzy T250 going last year. Didn't need near as much as yours but sure is a fun little ride. Will cruise at 60mph all day long as it's not even on the pipe yet at that speed.

    Good luck.
    #36
  17. sprouty115

    sprouty115 Long timer

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    Cylinder bores look about the same.
    Looked around for an engine, in fact I'm still looking. Frustrating doesn't begin to describe the process.
    As for the crank, even if I get another one I'll have it rebuilt. Bore Tech was recommended for the cylinders by Lyn Garland who gets high praise over on the 2-Stroke World site. Still waiting to hear back from them.
    Thanks for the suggestions on the pistons and autoluber (currently disconnected).
    #37
  18. markjenn

    markjenn Long timer

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    As I recall, there are some RD specialist engine rebuilders scattered around that do good work. You might consider just throwing the engine in an ice chest and shipping it to them. They know exactly what to look for and the tricks to getting a reliable engine.

    - Mark
    #38
  19. sprouty115

    sprouty115 Long timer

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    That would be the sensible thing to do, but I've already bit the bullet (and truthfully I'm really enjoying it).

    [​IMG]
    Top end by Soapy Loofah, on Flickr
    #39
  20. sprouty115

    sprouty115 Long timer

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    Crank - Got that sent off today to Vintage Specialties. Lyn gave me the heads up that it fits in a medium size flat-rate USPS box and ships for $11.75.

    Also figured out how the crank got bent on the stator side - take a look at the back of the rotor and the giant chisel marks.

    <a href="http://www.flickr.com/photos/37135917@N00/8347926206/" title="Rotor back with chisle marks by Soapy Loofah, on Flickr"><img src="http://farm9.staticflickr.com/8090/8347926206_000dcc964d_c.jpg" width="800" height="598" alt="Rotor back with chisle marks"></a>


    BTW, the back rotor (the piece with the all the marks) is loose and can rotate pretty easily. I assume it's not supposed to be able to do that?

    Compare this with the image above.
    <a href="http://www.flickr.com/photos/37135917@N00/8346868973/" title="Rotor back with marks by Soapy Loofah, on Flickr"><img src="http://farm9.staticflickr.com/8056/8346868973_fbba231968_c.jpg" width="800" height="598" alt="Rotor back with marks"></a>


    Cylinders - spoke to Bill at Bore Tech about the getting them bored and honed. $65/cyl, seems pretty reasonable? He suggested adding .50mm to the bore size (I measure 50.05mm) and ordering the appropriate pistons. That would put me at 2nd-over. He also suggested ordering the pistons and sending them to him along with the jugs. Doesn't seem to be as much out there for the 250 as there is for the 350, but there are some available from HVC Cycle.

    Other fun stuff - cleaned up the heads.
    <a href="http://www.flickr.com/photos/37135917@N00/8347979604/" title="Heads -bead blasted by Soapy Loofah, on Flickr"><img src="http://farm9.staticflickr.com/8329/8347979604_71d259ebbb_c.jpg" width="800" height="598" alt="Heads -bead blasted"></a>

    Started making a list as all the gaskets, seals and screws will need to be ordered and I don't want to forget anything.
    https://docs.google.com/spreadsheet/ccc?key=0AqqQvo3iGeMUdDB3bmp3NjVnQ0xsdkNxa3l6QWVxeFE
    #40