RT3 Motor in a Box

Discussion in '2 smokers' started by spokester, Apr 5, 2016.

  1. spokester

    spokester Long timer

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    An old buddy of mine who does a LOT of off road riding in New Hampshire wanted to spend the long winter refurbishing his recently acquired Yamaha RT3. To expedite the process he shipped me the engine to rebuild. Here's what came in the mail! DSCN9676.JPG

    Being a carpenter, he built a nice reusable box to ship it in. It came to South Carolina UPS for about $140.00 with insurance. Then I laid my grubby mitts on some SWEET Vessel JIS screwdrivers:clap DSCN9686.JPG

    Here's some of the initial findings.... DSCN9687.JPG DSCN9690.JPG

    Connecting rod is well aligned.
    #1
  2. spokester

    spokester Long timer

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    DSCN9691.JPG

    Connecting rod side clearance and small end shake are tight, crankshaft is running true, man, these Yamaha motors are TOUGH! DSCN9693.JPG DSCN9695.JPG DSCN9696.JPG
    #2
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  3. spokester

    spokester Long timer

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    As seen in my previous posts, my unbelievably awesome Czechoslovakian crankcase separator just keeps getting more awesomer!

    Clutch hub and basket along with the kickstarter mechanism and it's related parts are unhappy campers. Imagine the abuse that poor kicker endured over the decades! DSCN9699.JPG DSCN9702.JPG DSCN9703.JPG

    This pushes the crankshaft out of it's bearing and the crankcase... DSCN9704.JPG
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  4. spokester

    spokester Long timer

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    More Yamaha toughness, the cylinder was less than a thou tapered and out of round. The piston had been living happily within. Honed her a bit with the AMMCO rigid hone to restore roundness then finished off with a colossal bottle brush hone. Ended up with a sweet piston to cylinder clearance of just over three thou. Sandblasted the jug and sent her out for powder coating... DSCN9711.JPG DSCN9713.JPG DSCN9742.JPG DSCN9772.JPG

    Spark plug is blocking off the hole for the compression release, he he. To be continued...
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  5. spokester

    spokester Long timer

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    I took my sandblasting nozzle and stuck a pickup tube into a box of baking soda to address some unfortunate deep pitting on the top of the crankcase. It didn't do much to enhance their appearance. Another friend of mine suggested that Duplicolor Silver Brake Caliper paint was a dead match for the die cast aluminum...he wasn't kidding!:D DSCN9781.JPG DSCN9783.JPG DSCN9790.JPG

    I only painted the top affected area, not the whole crankcase. I love to install new bearings:D DSCN9791.JPG
    #5
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  6. dhallilama

    dhallilama Long timer

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    They're stout motors, aren't they?

    I've used the dupli-color silver brake caliper paint- the stuff holds up suspiciously well to chemicals like gas & carb cleaner, too. My Yamaha IT's jug is painted in either that or dupli-color silver high-temp paint (i think its' the same thing)... it's been there for a few years of abuse, gets hit with a pressure washer, gas has leaked all over it, carb cleaner, brake cleaner: looks as good as the day I sprayed it.

    for what it's worth- Greyhound & Fastenall both ship heavy items, usually significantly cheaper than USPS/FedEx/Etc. The drawback being that you have to drop off/pick up from their locations vs the UPS dude schlepping it up your stairs to the front door.
    #6
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  7. spokester

    spokester Long timer

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    Thanks, dhallilama. Good to hear you had good results with that paint. I initially wanted to duplicolor the cylinder for three reasons. I was concerned that powder coating would 1) hold in heat to the cylinder 2) not resemble the original appearance 3) be hard to highlight the edges of the cooling fins. But then...my buddy's nationwide search for a powder coater turned up a guy who just happened to live at the end of my street, so that was just too providential! He offers some unique services, he can even powder coat plastic and wood. Don't ask me how that works!
    #7
  8. spokester

    spokester Long timer

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    It turned out that every part of the kickstart mechanism, even it's related gears, needed to be replaced. My buddy did an amazing job of locating all of the genuine OEM parts needed. Try that without the interwebs! DSCN9788.JPG

    Here's the cylinder back from the powdercoater's, it was still warm! I used a variety of methods to highlight the fins, finishing with fine sandpaper. DSCN9799.JPG DSCN9800.JPG

    This heated metal plug is expanding the bearing's inner race so that the crankshaft will slide right in. I learned this trick from some really old East German two stroke service manuals. The vice grips are so that I don't burn my fingers. Mechanics have fire-proof fingers, but not that fire-proof!:imaposer DSCN9792.JPG
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  9. spokester

    spokester Long timer

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    Some really sweet assembly here, the precision and tolerances of the Yamaha parts are superb! All of the transmission gears and shafts were in fine condition. No iffy dodges were involved in getting this all together :) DSCN9793.JPG DSCN9795.JPG

    I couldn't decide what color to paint the piston, so I used the silver caliper paint to match the original metal finish. :rofl:rofl:rofl:rofl DSCN9802.JPG

    To celebrate the occasion, I sent my torque wrench back to Snap On to be recalibrated. Actually, I feared I had damaged it torqueing a Buell left hand threaded axle. There's a small label on the wrench saying to NOT use it counterclockwise. I didn't remember this until too late. I don't know why the wrench has a reversible ratchet head? That's what fooled me :):lol3:lol3:lol3 DSCN9804.JPG
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  10. spokester

    spokester Long timer

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    So, the head bolts were solid rust. After giving them the wire brush treatment I clearcoated them. DSCN9780.JPG

    I did me some TDC finding and verified the ignition timing marks... DSCN9803.JPG

    Set me some timing... DSCN9805.JPG

    Then sought approval from my peers... DSCN9807.JPG
    #10
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  11. spokester

    spokester Long timer

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    RIDDLE ME THIS, BATMAN...Why oh why...and I eagerly solicit info from our resident experts here...

    The only place in the crankcase casting that will allow oil, as added in the fill hole in the primary cover, to get over to the transmission side, would be fully blocked off by the drain plug when it's fully installed.

    That is, if you drained the oil, replaced the drain plug, then dumped a quart into the dipstick filler cap (as per the manual), all of the oil would be in the primary cover. There are a few oil deflector plates and oil channels, but no direct pathway for oil between the transmission and the primary.

    I considered a shorter drain plug, or even drilling a hole through this one. I suggested adding the oil with the drain plug only slightly screwed in, waiting for the level to equalize, then fully tightening the drain bolt.

    Any helpful suggestions from our inmates? DSCN9810.JPG

    Mr. kickstarter shaft was one of the parts that needed to be replaced. DSCN9811.JPG DSCN9815.JPG

    Compression release needed some love and a few fiddley parts. DSCN9816.JPG
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  12. spokester

    spokester Long timer

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    Here's the nice new kickstarter stuff. You have to get everything just right here, there's more than one way to misassemble this gadget.

    It was helpful to do a bit of polishing on the parts that allow the engagement segment to slide on the shaft. DSCN9864.JPG

    This made a loud clunk when I dropped it into the letter box! DSCN9917.JPG

    A bit of celebration was considered to be in order, the Yammie motor is under the yellow towel in the back ground! DSCN9819.JPG :photog:photog:photog
    #12
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  13. Scootern29

    Scootern29 Long timer

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    "Some really sweet assembly here, the precision and tolerances of the Yamaha parts are superb!"

    It really is amazing how good the machining and fit of the Yamaha motor is. They are pretty indestructible in my opinion. Your work is top notch. I've been following this thread as I have 5 Yamaha Enduro's and MX's.
    #13
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  14. spokester

    spokester Long timer

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    Thank you, Scootern, I follow all of your posts as well!:D I really appreciate your thumbs up!:clap
    #14
  15. spokester

    spokester Long timer

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    Scootern, do you have any ideas on the drain plug situation?
    #15
  16. Ilbikes

    Ilbikes Been here awhile

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    Hi spokester, I have the DT3 version of that same bike/engine. You may remember, it's the Green 250 that Lanny received for me when I had it shipped from Oregon. I've got the factory shop manual that I think has a diagram of lubrication. Let me have a look tomorrow and see if it will give some insight.
    Gordon
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  17. Scootern29

    Scootern29 Long timer

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    I have never looked that closely at the drain plug area and that is quite interesting. Maybe it is the wrong drain plug? I don't know why drilling a hole next to that one would hurt any thing unless there is something on the back side. That just seems weird to me that Yamaha would do that compared to every thing else in the motor that is well thought out.

    Things that make you go Hmmmmmmm.
    #17
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  18. Scootern29

    Scootern29 Long timer

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    Come to think of it. I may have a drain plug I could measure the length of and see what the difference is.
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  19. spokester

    spokester Long timer

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    Thanks for your help, Scootern. I have e-mailed the owner to get a shorter drain plug. There's not a lot of thread in the crankcase. Just odd how this is, I came very close to overlooking the whole situation. Thanks for your response!
    #19
  20. spokester

    spokester Long timer

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    Thank you, Gordon, I look forward to seeing what you find out. There's not much thread in the crankcase casting beneath that horizontal hole.
    Thanks for checking!
    #20