TDC locking bolt

Discussion in 'Crazy-Awesome almost Dakar racers (950/990cc)' started by fmfpunk, Dec 26, 2007.

  1. fmfpunk

    fmfpunk Hooligan in training

    Joined:
    Jun 3, 2006
    Oddometer:
    1,177
    Location:
    La Verne, CA
    Getting ready to check my valves, and wondering what's the purpose of this locking bolt.
    Guessing that it's to hold the crank from moving while you have the cams out, because there's no TDC marks on the crank, only on the cams?

    What can i use in place of this special tool?

    thx.
    #1
  2. cpmodem

    cpmodem Orange Caveman

    Joined:
    Nov 29, 2004
    Oddometer:
    7,103
    Location:
    masa yee yah tee 59° 14' 9" N / 135° 26' 42" W
    Before I had the locking bolt, I just used a long phillips screw driver.
    #2
  3. Tim McKittrick

    Tim McKittrick Long timer

    Joined:
    Dec 29, 2003
    Oddometer:
    1,919
    Location:
    Wasilla Alaska
    Just make one- when you remove the bolt that fills the stop bolt hole in the right case take it by the hardware store and get one of the same thread pitch but about twice the length. Or, if you're like me, root about in the bins of crap in your workspace unti you find one. Then make a point on it with your grinder or a file. If you make it about a 30 degree taper it'll work just like the factory tool. Done! Add it to your tune up tools.
    #3
  4. VintageThumper

    VintageThumper Gotta ride!

    Joined:
    Jun 6, 2006
    Oddometer:
    1,061
    Location:
    Salinas, CA
    If you want the official bolt, it's 0113080802. If you want to make your own, it's 8mm x 80mm x 1.25mm thread pitch. As Tim said, it has about a 30 degree point on one end, and is machined for a hex key in the other. But I'm sure a regular screwdriver slot would work too. Here's a pic...

    Attached Files:

    #4
  5. fmfpunk

    fmfpunk Hooligan in training

    Joined:
    Jun 3, 2006
    Oddometer:
    1,177
    Location:
    La Verne, CA
    thx guys. I'll grind one here at work.

    But would u explain why you need the bolt? If you don't uses the bolt is it possible to screw up cam timing?

    thx.
    #5
  6. HellsAlien

    HellsAlien a has-been that never-was

    Joined:
    Nov 16, 2004
    Oddometer:
    2,759
    Location:
    Baja Sur winter. PDX summer (that's like 6 wks!)
    Yes it is possible, the valve springs pushing back from the "other" cylinder not being valve-checked can roll the crank. Spin the crank with a wrench and you will know what I mean.

    If you do pull the cams be sure you understand the markings on the gears, they are not intuitive or easy to read, esp on the front cylinder. I mark the teeth with red paint to aid reassembly. Have fun, is not that tough a job!

    Thread hijack: So whats the hot deal on FMF repacking for the 950? My Q's are getting loud!
    #6
  7. tahoeacr

    tahoeacr Long timer

    Joined:
    Jan 7, 2007
    Oddometer:
    2,223
    Location:
    Lake Tahoe
    I've done the valves at least three times and never bothered with it. Never had a problem. The only time I had a prob was when I had a degree wheel on the crank trying to check the lift of the cams. You could probably leave the bike in gear to add a little resistance.

    Get that thing goin and let's go race the Adelanto GP and pester Paul. Tell him I said hi.
    #7
  8. BLUE(UK)

    BLUE(UK) Long timer

    Joined:
    Dec 2, 2004
    Oddometer:
    3,423
    Thanks to VintageThumper for the pic,i made two using normal bolts of the correct thread and grinding a point on the end of each.
    I have now done my valves-just need to rebuild it-anyway,i ordered the KTM bolt so i dont need the two i made(they work perfectly adequate),so if any UK people want one(there is 2 available),first 2 people to PM me their address gets one in the post.

    Yep,FREE!!(KTM locking bolt is about 4quid and will most likely need ordering.

    As i said,first 2 people.
    #8
  9. Venteuri

    Venteuri I don't give a shit

    Joined:
    Sep 3, 2007
    Oddometer:
    17,261
    Location:
    Queretaro , Mexico
    Why does it need to have angle in the point?

    Can I use a screw on the correct dimension?
    #9
  10. emelgee

    emelgee Been here awhile

    Joined:
    Jun 4, 2006
    Oddometer:
    870
    Location:
    Sheffield, UK
    It'll make it easier to locate in the corresponding recess - the point will kind of guide it into the hole.
    #10
  11. cpmodem

    cpmodem Orange Caveman

    Joined:
    Nov 29, 2004
    Oddometer:
    7,103
    Location:
    masa yee yah tee 59° 14' 9" N / 135° 26' 42" W
    ... especially on the rear cylinder (due to valve spring pressure forcing the crank past TDC). One trick I use when inserting the locking tool is bring the cylinder just short of TDC then insert a phillips screw driver or other pointed tool into the locking tool's hole and put slight pressure against the crank as I slowly turn the engine to TDC. That way I can feel the recess that the locking bolt needs to go into and stop the crank from slipping past. I then insert the locking tool. The top of the locking tool should be flush or slightly recessed with the engine case. Hope this helps some folks.
    :freaky

    Should look like this:
    [​IMG]

    NOT like this:
    [​IMG]
    #11
  12. G$

    G$ Lack of Adventurer

    Joined:
    Apr 5, 2005
    Oddometer:
    990
    Location:
    Above Jamestown, CO
    For everyone who contributed to this thread, I just like to say thanks. This as well as many other threads here are invaluable. :clap

    G
    #12
  13. ridewestKTM

    ridewestKTM Long timer

    Joined:
    Jun 7, 2007
    Oddometer:
    1,755
    Location:
    now in Katy TX
    All said are good points - I made one out of aluminum so no chance of damaging things -good bad whatever it works. BUT as another thread discussed; what the hell do you do if you forget to back it off and turn the crank and either break or bend the bolt??? That'll ruin your day, week month. As said may be just don't use the bolt, and hope you can find TDC if it moves while you have a cam out. Here is what I think I'll do in future: Tie a lanyard between the lock bolt and my crank-turning tee -or some derivation of that scheme, so I can't turn the crank without at least making me think about the bolt.
    #13
  14. 990adventuredes

    990adventuredes Adventurer

    Joined:
    Aug 20, 2012
    Oddometer:
    10
    Location:
    Dublin Ireland
    would this locking bolt work to stop the engine rotation to remove the ignition rotor ? i am using a manual torque wrench.
    #14
  15. RedRupert

    RedRupert Brit in the Soviet Union

    Joined:
    Jun 12, 2006
    Oddometer:
    633
    Location:
    Riga, Latvia / Bergerac, France / Colchester, UK
    Yes.
    #15
  16. Tim McKittrick

    Tim McKittrick Long timer

    Joined:
    Dec 29, 2003
    Oddometer:
    1,919
    Location:
    Wasilla Alaska
    It might work- but it's a poor notion as if it fails you risk damaging the case and crankshaft.

    I'd use the old airman's "rope trick" instead- feed a short length of small diameter cord through a sparkplug hole into one of the cylinders on it's compression stroke to jam between the piston and head and stop the motor from turning. The soft cord will prevent the engine from spinning but won't damage anything as you remove the rotor bolt.
    #16