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Thread: crisis?

  1. #1
    Member amolaver's Avatar
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    So the intake adjuster lock nut backed off and got loose in there. i fished the nut out and it is has some dings on it, but otherwise seems ok. i bought some replacement nuts and reset the valve lash...and got no results. removed the covers again doublechecked the clearances; all good. bad news is that with the covers off i can hit the starter and see no action from the rockers. i'm guessing the nut rolling around in there either broke the cam or the chain.



    any suggestions for how to troubleshoot past this? i've never had a head off a motor, but i guess an old-tech motor like this is probably one of the best to give it a whirl. looking to any and all suggestions / tips. thanks



    ahm

  2. #2
    Member amolaver's Avatar
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    really, no suggestions? engine was running fine, then died. no bad noises noted, but clearly something bad happened. after resetting the valve clearance and thumbing the starter, i see no movement from the rockers. i take that to mean one of a coupe bad things might have happened:



    1) cam chain broken / derailed (not sure if thats possible)

    2) cam itself broke.



    looking for guidance on a) theories on broke, and a process to take the head off that is likely to cause the least amount of further damage. is it as simple as removing the head/frame bolt and the 4 long bolts going through the head, then lift off (assuming chain is not still intact)?



    i really don't want to take this to a dealer as i know they'll end up charging me as much to fix it as buying a new tw would cost

  3. #3
    Member amolaver's Avatar
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    [media]http://molaver.org/tw200.camchain1.jpg[/media]



    [media]http://molaver.org/tw200.camchain2.jpg[/media]



    so, more info to the pile. it would appear that when the valve adjusting nut spun off the adjuster, it managed to lodge itself between the upper cam gear and its keyed nut, causing mayhem. i can see that the gear's keyway is beated to death, as is is the keyed nut.



    thoughts at this point? scrap the motor? is the cam gear driving the cam directly (ie, the cam itself is dicked) or...? suggestions on how to proceed?

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  5. #4
    Senior Member davidsonsgccc's Avatar
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    there is link to service manual download in the technical section. you should be able to find an exploded view of you engine mechanical workings.maybe you can replce cam only?
    not a TW owner but i play one on this forum.

  6. #5
    Member amolaver's Avatar
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    i've got the service manuals, but they are a little light on the 'noobie, do this first' type of instruction i've got the cam out, and it is clearly trashed. the dowel pin broke out of it, which mangled the keyway in the camchain gear. i can order the parts and probably even put them back in, but 1) how do i 'time' the chain to the new gear, and 2) any way to know if there is any valve damage? i'd hate to put it all back together and realize i broke a valve.



    i just don't see the description of a process to remove the head in the service manual. am i missing it?



    ahm

  7. #6
    Senior Member lizrdbrth's Avatar
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    Quote Originally Posted by amolaver View Post
    i've got the service manuals, but they are a little light on the 'noobie, do this first' type of instruction i've got the cam out, and it is clearly trashed. the dowel pin broke out of it, which mangled the keyway in the camchain gear. i can order the parts and probably even put them back in, but 1) how do i 'time' the chain to the new gear, and 2) any way to know if there is any valve damage? i'd hate to put it all back together and realize i broke a valve.



    i just don't see the description of a process to remove the head in the service manual. am i missing it?



    ahm


    No way to tell about valve/piston damage without either pulling the head or installing the new cam and hoping for the best. In either case odds are some schrapnel found its way into the bottom end through the cam chain tunnel, so I'd pull the motor out of the frame, drain the oil and pull the sidecovers and give it a good solvent flush, minimum.



    I can explain it to you, but I can't understand it for you.

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  8. #7
    Member amolaver's Avatar
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    managed to get the head off (just those two little allen heads plus the 'big 4' and carb boot), and inspected the valves. they all look clean - no chipped edges, piston top looks good. have pictures of the cam and cam gear - not pretty. the dowel from the cam is just gone. i wish i could just post pictures here w/o having them hosted somewhere else, but whatever. while it may come back to bite me, i'm not going to solvent flush the bottom end. i'll dump the oil, fill it with cheapo stuff, run it for 10 minutes, dump it and clean the filter, repeat. i know you have the more thorough plan, but i just don't have the inclination.



    anyone know if you order the cam, the dowel shows as a separate part - must it be pressed in to some spec, or...?



    ahm

  9. #8
    Member Babaganoush's Avatar
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    Quote Originally Posted by amolaver View Post
    anyone know if you order the cam, the dowel shows as a separate part - must it be pressed in to some spec, or...?



    ahm


    Hi AHM,

    I recently had a similar problem in the Spring when my engine ran like crap and died on me 15 miles from home. I pulled the head and found the intake nut and screw had come loose and were found in the bottom of the valve cavity. My cam and chain were OK but the intake valve and guide was broken. I bought the parts from Powers Edge :

    http://www.powersedge.com/pages/part.../2/Yamaha.aspx . Look up your year and you will be able to tell what parts you need. Make sure the valve adjustment screw will thread OK. My rocker arm was boogered up in the thread and almost made me have to tear the engine down again. I made a special tool to pull out the intake rocker shaft. I bought a 2ft threaded rod and bolted a block of wood to the end. I threaded the rod into the end of the shaft and had the other end with the wood block in the jaws of a vice. This let me slam the head toward the ground with the block of wood stopped by the vice (same as a slide hammer). The shaft made its way out easily and without damage. I had a machine shop install the valve guide. the parts were less than $85.00 and the machine shop was $90.00 (which I thought was kind of expensive). I recommend buying an new adjusting nut and screw since the threads are so fine they are easily damaged and don't forget a new head gasket. Check over the head carefully so you only have to place one parts order. Good Luck,



    Dave

  10. #9
    Member amolaver's Avatar
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    [media]http://www.molaver.org/tw200.head.jpg[/media]

    [media]http://www.molaver.org/tw200.cam.jpg[/media]



    sorry to hear about your troubles. this sounds like the two possible outcomes of the nut coming off; yours, going down the intake tract, and mine bouncing off the rocker and heading for the cam/chain/gear.

  11. #10
    Senior Member Snake2715's Avatar
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    wow keep us updated, I am new to this bike, so I have no suggestion, other than take your time, but it sounds like you are an experienced, self proclaimed newb.



    Also Photobucket does an excellent job if you need a picture host.

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