WR250R Engine Rebuild

Discussion in 'Thumpers' started by WHB_P, Nov 2, 2013.

  1. WHB_P

    WHB_P Adventurer

    Joined:
    Sep 23, 2013
    Oddometer:
    36
    Hello Inmates!

    Preamble
    Thought I’d start this thread to document the rebuild of my WR250R, and solicit thoughts from the very accomplished mechanics on this site. I’ve never torn into an engine before and look forward to the community’s input as I tackle this project. My current pictures are not great, but I will do a better job of documenting progress as I move forward. I hope that documenting my experiences can be helpful to those approaching similar problems in the future.

    Background
    I purchased this ‘08 WRR with 7,000 miles from a fellow inmate, with the understanding that it needed some engine work (having gone for a bit of a swim). The bike was running fine, but consuming oil. There was no smoke in the exhaust.

    Before I get into the pictures and details, I’d like to thank the folks who have put an amazing amount of WRR info on the web: Rick Ramsay, Highfive & Krabill, Basher Designs, and the numerous inmates with highly detailed engine rebuilds on this site.

    Meat & Potatoes
    The first diagnostic I performed was to run a leakdown test. I wasn’t looking for specific numbers, but rather wanted to pressurize the cylinder and attempt to identify any leaks. I could hear air escaping out the exhaust and from the crankcase (I removed the oil filler cap). Seems like the exhaust valves & piston rings are letting some air out.

    If the top end had seemed solid, I likely would have taken the engine to a pro given my inexperience and fear of splitting cases. However, having identified some easily addressable top-end issues, I decided dive in myself. Given that I lack a garage and enjoy the convenience of working indoors, pulling the engine seemed like the right choice.

    Here’s a picture of the engine in my "workshop":
    [​IMG]

    When covering engine openings, I’m a big fan of the used-nitrile-glove-over method in lieu of the paper-towel-stuffed-in approach. I’ll also point out that dropping the engine and lower frame as one unit makes an easy one man job (using ratchet straps to lower it all), and provides a built-in engine stand.

    I also took a look at the oil filter, and didn’t see any metal shavings or evidence of grenading engine, though I have no idea how long it’s been in there:
    [​IMG]

    Tore out a piece for a closer look:
    [​IMG]

    Enough of that. Let’s get started with the teardown. First step is removing the cylinder head cover:
    [​IMG]

    So far, so good:
    [​IMG]

    The factory workshop manual instructs to remove the cam chain tensioner at this point. I stupidly followed along, before having checked valve clearances. Since the engine was not at TDC and it’s hard to rotate without cam chain tension, I decided to keep going without getting baseline clearance numbers.

    Unbolted the cam cap, being careful to “break” torque from the bolts a little bit at a time, and in the reverse order from the tightening sequence marked on the part:
    [​IMG]

    Cam cap bolts are all the same length:
    [​IMG]

    What do we think of the bearing surfaces? Look fine to me:
    [​IMG]

    I realize that my pictures of the cams themselves are fairly blurry, but here they are:
    [​IMG]
    [​IMG]

    Cams looked completely smooth to me, with no visible wear or other issues.

    I proceeded to remove the cams, securing the timing chain to the uppermost bolt hole of the engine mounting frame. Again, helpful to have the frame here if you’re working on the engine outside of the bike. As you may be able to deduce, I cannot find my stash of zipties and had to improvise. Is a project without zipties destined to failure?
    [​IMG]

    Removing the cylinder head is straightforward, with 4 hex bolts and 2 Allen head bolts. All 6 fasteners have captive washers, so no need to worry about those falling into the crankcase. When removing the cylinder head, be mindful not to lose the 2 dowel pins visible in the photo. Also, make sure to take note of where the 1 longer hex bolt goes:
    [​IMG]

    Well, there she is. Let’s take a look at the piston:
    [​IMG]

    The carbon buildup on the right of the piston is actually several millimeters thick, as shown in this photo:
    [​IMG]

    Next step was pulling the cylinder itself. Very easy to do, with only 2 small bolts on the left side. No pictures of the removal, but here’s the bore:
    [​IMG]
    [​IMG]
    [​IMG]

    The first pic seems to show signs of “vertical scratches.” According to the service manual, the remedy is to “Rebore or replace the cylinder, and replace the piston and piston rings as a set.” The vertical scratches seem like evidence of the piston rings being exposed to contaminants or corrosion, which would explain the air passing through to the crankcase when I performed the leakdown test.

    It would be great to get the group’s thoughts on the cylinder bore.

    Having removed the cylinder, I took a look at the piston. The smudges on the piston skirt in 1st photo are just carbon from my finger:
    [​IMG]
    [​IMG]
    [​IMG]

    At this point, I took a break for some food. Chili-cheese fries and a double Spike’s burger – healthy perfection:
    [​IMG]

    Back at it. I removed the piston, which looked like this:
    [​IMG]

    And the wrist pin, which looked like this:
    [​IMG]

    The workshop manual says that for any “Blue discoloration/grooves” the remedy is to “Replace the piston pin and then check the lubrication system.” I can’t tell whether the two large matte areas I’m seeing are a design feature or a result of inadequate lubrication. Anybody know?

    The last thing I did today was take a look at the head. In order to determine whether valves are seating properly, the service manual suggested pouring solvent into the intake/exhaust and seeing whether any leaked through. I thought it sounded like a good idea:
    [​IMG]

    Intake valves were sealed up tight, but you can see some solvent coming past the exhaust valves. This would agree with the air heard escaping the muffler during the leakdown test.

    That concludes the day's progress. I have a number of questions where I would greatly appreciate the group’s input.

    Cylinder: I would actually prefer not to install a big-bore kit (to avoid the need for a tuner and the tradeoff in high RPM highway vibration). Assuming I try to stay stock, I have the following questions:
    o Does the cylinder appear to need repair/replacement?
    o If I opt to repair, what is the most cost-effective approach? A new Yammy cylinder is nearly $400. Not cheap!
    o Is it possible to just replace the insert?
    o In order to hone out the scratches, would we have to end up overbore?
    o If a repair means boring things out, can I buy oversize rings, or do I need a new piston?

    Cylinder head:
    o I plan to send this out to a motorcycle machine shop and have them do a standard cleanup, with no fancy headwork. Anybody have a good shop in the Boston, MA area?

    Piston wrist pin:
    o Do the matte-colored areas appear to be evidence of an oiling issue, or is that just how it's built?

    Next steps:
    o Should I pull the right-side crankcase cover and take a look at the oil pump screen?
    o Do we think it’s necessary to continue the teardown, split the cases, and replace bottom-end bearings?

    Thanks in advance!
    #1
  2. ruppster

    ruppster Been here awhile

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    I'm not sure of the answers to your mechanical questions, but the cylinder wall looks scratched, maybe you could just hone it and use some new rings. You know you need some upper end work. There is a WR250X engine on eBay for about a grand. I'd add up your rebuild costs before deciding, especially if staying stock cc's. At $400 for a cylinder it won't take long to get there.
    #2
  3. ragtoplvr

    ragtoplvr Long timer

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    If you hone enough to get the scratches out, the piston will almost certainly be too loose, and it will possibly burn oil and have piston slap. That engine is pretty high rpm and those rings are very thin. That normally means touchy about clearance and condition. Overbore or new jug is the best way

    Rod
    #3
  4. AZ TOM

    AZ TOM Long timer

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    Priceless input. Thanks.
    #4
  5. cjbiker

    cjbiker Nobody's Robot

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    :lurk

    I'm glad to hear that there's no catastrophic damage so far. I'd call these guys about getting the cylinder repaired. They can bore it out and replate it. http://www.mt-llc.com/

    I'm curious to know what the valve clearances are. I checked them at 4000 miles and they measured at 0.009" and 0.010" on the exhaust and 0.006" on both intake valves.

    As for the head, I would just lap the exhaust valves to get them to seal and call it good.
    #5
  6. WHB_P

    WHB_P Adventurer

    Joined:
    Sep 23, 2013
    Oddometer:
    36
    Thanks for the advice. My approach to an eBay engine is that it's a complete mystery regarding condition. How does the saying go? "Rather the devil you know..."

    :dunno

    That makes a lot of sense, and aligns with my thoughts. I may be able to find a low-mileage take-off cylinder out of a bike that had the Athena/TR kit installed.


    Fancy meeting you here! Appreciate the link, and I'll plan to get in touch with MT tomorrow. Agree that the head doesn't necessarily need a full re-work, but I'll probably get a quote before deciding.
    #6
  7. WHB_P

    WHB_P Adventurer

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    I'm starting to feel pretty good about the path forward. Only remaining question is whether the group thinks I ought to give attention to the bottom end.

    The one indication of oil starvation would be the marks on piston wrist pin, although I'm still not sure whether these are meant to be there. Anybody familiar?
    [​IMG]

    Finally, I found the following discoloration on the crankshaft, right where the connecting rod attaches. Is normal?
    [​IMG]
    [​IMG]
    #7
  8. rudk

    rudk Been here awhile

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    108
    I don't get one thing....are you "measuring" that engine and its components
    "by eye" or do you have the necessary precision measuring tools (dial indicator, micrometer, rulers etc.)?
    #8
  9. WHB_P

    WHB_P Adventurer

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    Looks like I'll be shipping the cylinder & head out to Millennium Technologies. They'll hone & replate the cylinder to factory bore and have their sister shop, XPort CNC, do a valve job on the head. In the next couple days, I'll pull the right side case cover and check the oil screen for any debris. Assuming that looks clean, I think I'll be leaving the bottom end alone.

    If I were simply taking a high-mileage engine down for a "refresh," it would make sense to measure parts and compare to the specs in the workshop manual, such as cylinder bore and taper dimensions. To continue with the cylinder example, because this engine has visible damage there, there isn't a need to measure to know we'll need to make changes.
    #9
  10. rudk

    rudk Been here awhile

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    A lot of bikes have those vertical scratches on the cylinder walls if you look at the long term reviews like for ex. german "Motorrad" magazine.

    2012 Honda CBR600F

    [​IMG]


    [​IMG]



    2010 Honda CBR1000RR

    [​IMG]



    Triumph Tiger 800 XC

    [​IMG]


    If the parts are in spec according to the manufacturer operating tolerances they usually don't replace anything. That's why I've been asking how you measure them. Anyway, good luck.
    #10
  11. StevenD

    StevenD Hmmmm, dirt!

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    cylinder looks pretty much ok... can you feel the markings or not? measure it before spending a whole lot of cash on replating a bore that meight be ok still.

    Wrist pin markt, normal. blue color on crank is normal as well.
    #11
  12. rdouthit

    rdouthit Adventurer

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    +1
    #12
  13. pne

    pne Been here awhile

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    honestly I would have just put it back together and kept running it. I had my wrr from new, and it used oil too despite never having gone for a swim.
    #13
  14. WHB_P

    WHB_P Adventurer

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    Thanks for the input. I can't feel the cylinder scoring, and agree that it seems pretty minor. Not sure if I'll still send to MT, but probably will for peace of mind.

    Thanks!

    The oil consumption was to the point of needing a top-off every 200 miles. For a bike that I hope to do some distance on, that didn't seem very fun.
    #14
  15. WHB_P

    WHB_P Adventurer

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    Thanks! I agree that those markings don't look any worse than my bike. I've attached the page from the Yamaha service manual with measurements and instructions in the event of "vertical scratches."

    [​IMG]
    #15
  16. NJ-Brett

    NJ-Brett Brett

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    If it was me, I just would have went for the big bore kit.
    If you use oil on a plated bore bike, I would just replace the cylinder, piston, rings and wrist pin.
    In many cases, a new cylinder is about the same price as having it replated, and its new!

    It pays to price out a big bore kit, a new stock cylinder on bike bandit, and the replate.

    When you have dirt/water into the motor issues, the bore and rings are the first things to go, and the other stuff holds up fine in most cases.

    I have an old XT200 that was run with no air filter and no oil changes, and the rings were totaly shot, the bore (not plated) was worn but ok, and the rest of the motor was great.

    The plating used is hard, modern rings are thin, so you might have been able to get away with just doing rings, but I would do it up right and do the piston, rings, wrist pin, and cylinder as a set, and its like a new motor.

    And I would not do that without fitting a big bore kit for more torque.
    #16
  17. HardWorkingDog

    HardWorkingDog Harvey Mushman

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    Agree with most of ^^^, with the exception of a big bore. I'm not convinced it's a good route, funny how many of the owners put in a big bore kit and wind up selling the bike a few months later...

    The new cylinder is going to be a bit more than a replate--say $100--the replaters know the market. And every time I've gone the replate route I tell myself never again :lol3 The peace of mind with a new cylinder is hard to discount.
    #17
  18. kawagumby

    kawagumby Long timer

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    I've noticed that too. I've also noticed that several guys who did the big bore said it was not the best use of the money, in retrospect.
    #18
  19. WHB_P

    WHB_P Adventurer

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    Thanks for the thoughts. My plan is to replace piston, rings, wrist pin, and plate cylinder (~$190). Stock replacement cylinders are $390 at the cheapest, and a big bore kit is just over $700.

    In this case, new goes $200 over replate, so I'll probably stick with the plate.

    :thumb I'd rather spend the money on gas and tires.
    #19
  20. pne

    pne Been here awhile

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    I'm convinced of this as well (both accounts). The draw of the wrr is the rock solid reliability and you are definately giving that away with the big bore kit. Same with the replate, I could never trust those companies to do as good a job as OEM. I've had some replated cylinders that lasted about 12 hours before they were toast. I gotten back jugs where they "matched" a piston to, measured both, and it was off by all accounts.

    If there's no scoring on your jug, sell that on ebay and it will help offset a new jug.
    #20