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Help Honda CBF250 aka CBX250 Twister 06 setting up TDC & valves orientation problem

Discussion in 'Honda 250cc Singles' started by hogclassics, Aug 15, 2022.

  1. hogclassics

    hogclassics Active Member Premium Member

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    Hi riders & wrenchers.

    I’ve just replaced the seized & worn piston and barrel off a CBF250.

    The new valves, seals are all lapped the cams and springs are in spec.

    Just realized the chap who was helping me, took the 2 camshafts off (not finding TDC first) and got the cams mixed up. He didn’t take any photos and I came home to find he was away with work. The camshafts were loose in a container needing orientation. The manual doesn’t show any photos of how the camshafts should orientate correctly?

    One video on Utube shows the 2 cams with the woodruff hole at the top.

    When my buddy took the cylinder head off, the cams were upside down with the woodruff holes at the bottom.

    I understand that there are 2 TDC’s one for the exhaust and the other for compression.

    Q) How should the cams be for the TDC compression stroke, with the woodruff to the top of the camshaft or on the bottom of the camshaft please?

    When the cylinder head came off the cams were upside down and not link to TDC compression stroke.

    I would greatly appreciate any advice as I expected to find all the answers in the manual. There is nothing about TDC compression stroke or the correct orientation of the camshafts.

    Many thanks everyone!

    Best regards

    Hog
     
  2. Murdo

    Murdo The Good Doctor Staff Member Contributing Member Ride and Events Crew

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    The camshafts must have the lobes facing away from the valves.
     
  3. hogclassics

    hogclassics Active Member Premium Member

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    Hi Murdo

    Thanks for your reply.

    I actually was hoping for a lot of very informative replies.

    There is not enough info in the manual. I’m doing this for the first time as my buddy left me to it.

    There are 360 degrees of many variables here Murdo. Is there any supplementary visual info I could see please This would me greatly.

    On Utube they show a CBF125 with the camshaft woodruff slots at the top.
    Are they all set like that?

    Thanks again mate

    Hog
     
  4. thebeefsalad

    thebeefsalad Well-Known Member

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    Page 7-20 of the service manual clearly states that the crankshaft flywheel timing mark should be lined up with the notch on the cover. Pictures in the manual show the cam woodruffs are facing up, and cam timing marks should be parallel to the upper surface of the cylinder head
     
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  5. hogclassics

    hogclassics Active Member Premium Member

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    Hi Murdo.

    Many thanks for all your help buddy.
    All sorted now. My mate who helped me tore it apart anf then went away. He took the cams out upside down and not at TDC.

    I put it all together and marked the cogs with Tippex showing the vertical and horizontal lines and the cams lined up.
    The engine rotates and ends up at ‘T’ for TDC compression stroke and all the vertical and horizontally lines are spot on end up with the woodruff at the top.

    The manual really needed this info, it’s important or your motor goes bang!

    The beers or other drinks is on me Murdo.

    Bless ya mate!

    Best regards

    Hog
     
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