Page 1 of 3 1 2 3 LastLast
Results 1 to 10 of 25
  1. #1

    Weird msx 140 crank

    Hi, after a while of tinkering in spare time I think I found the fault of why my msx 140 was misfiring.
    Just took engine out today and got each cylinder to tdc and it looks like the middle cylinder may be firing too late as flyweek trigger fins are quite a bit after tdc on mid cylinder. (check pictures)
    the other two cylinders are spot on in the middle of the trigger fins at tdc. (check pictures)


    my question is why is it doing this?
    all cylinders including the middle is reaching the proper tdc, compression good, and the con rod isn't bent..
    what could be the cause of the it of the out of sync crank/flywheel just on the middle, but still have proper tdc on all cylinders.

    The first picture is the middle cylinder, the other two is mag and pto.


    Thanks
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	image.jpg 
Views:	76 
Size:	107.5 KB 
ID:	325584   Click image for larger version. 

Name:	image.jpg 
Views:	67 
Size:	98.0 KB 
ID:	325585   Click image for larger version. 

Name:	image.jpg 
Views:	70 
Size:	117.9 KB 
ID:	325586  


  2. #2
    Banned User
    Join Date
    Jun 2010
    Location
    Milwaukee WI
    Posts
    16,708
    +1
    1,324
    Did you check the crank for twist/ out of phase? Sheared flywheel key?

  3. #3
    Hi, no sheared flywheel,
    could out of phase cause it to be this much out? And the piston still hit tdc?

    how do you check for crank twist? And how can this be fixed if it is this?

    cheers

  4. #4
    Click avatar for tech links/info, donation request K447's Avatar
    Join Date
    Jul 2007
    Location
    near Toronto, Canada
    Posts
    36,596
    +1
    1,276
    Quote Originally Posted by FasterBaby View Post
    Hi, no sheared flywheel,
    could out of phase cause it to be this much out? And the piston still hit tdc?

    how do you check for crank twist? And how can this be fixed if it is this?

    cheers
    Check for correct 120 degree flywheel angle between each piston reaching TDC.

    One method. Wrap masking tape around the perimeter of the flywheel. Set MAG to TDC position, mark tape and label MAG.

    Do the same for CEN and PTO.

    Mark where tape overlaps itself. Then remove tape. Measure distance between each pair of marks. Should be the same for all.

  5. #5
    Hi cheers..

    ok i checked they are out of phase (middle cylinder firing too late) ...

    but what is the problem with the crank? And how can it be fixed?

    Can a twisted crank be fixed by truing? Or is it another fix?

    How do i check if the crank is twisted when the crank is out?

  6. #6
    Click avatar for tech links/info, donation request K447's Avatar
    Join Date
    Jul 2007
    Location
    near Toronto, Canada
    Posts
    36,596
    +1
    1,276
    Quote Originally Posted by FasterBaby View Post
    ... they are out of phase (middle cylinder firing too late) ...

    but what is the problem with the crank? And how can it be fixed?

    Can a twisted crank be fixed by truing? Or is it another fix?

    How do i check if the crank is twisted when the crank is out?
    The crank needs to be looked at by a shop that knows what they are doing.

    The crank is pressed together, working on it requires a 25 ton type press.

    I cannot say exactly how the crank got out of phase. Perhaps it was assembled incorrectly.

  7. #7
    K447,
    this i prob a dumb question, but would you check out my first picture posted on this thread and tell me if that is normal for the middle cylinder?
    i was thinking the three fins together are the trigger for the cps to fire that cylinder? Is that right?

    and as the middle cylinder was not lined up at tdc in the middle of three flywheel fins to cps, like the other two cylinder. I thought the crank was out.

    Does tdc of each cylinder line up with the three fins on flywheel with the cps? (First picture is middle cylinder tdc on flywheel with cps on top)

  8. #8
    Click avatar for tech links/info, donation request K447's Avatar
    Join Date
    Jul 2007
    Location
    near Toronto, Canada
    Posts
    36,596
    +1
    1,276
    I do not have any of my Ficht flywheels handy at the moment.

    The 120 degrees between piston TDCs is easy enough to measure using the tape around the flywheel method, or you can measure the angle directly in some manner.

    Don't just look at the flywheel fins. Look at the flywheel angles between each cylinder and the next. Everything is measured from the MAG piston and flywheel position MAG.

    Also keep in mind that the flywheel timing signals to the EMM do not come when the piston is at TDC. The timing triggers happen well before TDC so the EMM can properly sequence the fuel injection and then the spark, all this happens before TDC.

    What do you know about the history of this engine?

    Was it recently rebuilt? Has it ever run properly since the rebuild?

  9. +1 by:


  10. #9

    Join Date
    Aug 2006
    Location
    Homer Glen Il.
    Posts
    8,704
    +1
    109
    pull the heads and put up one piston to the top and then one of the other two should be up exactly the same , I usually line them up to one of the tops of the cylinder ports that way it's easier to tell if there off . also do it for all three pistons to tell which one is off or buy a dial indicator and use a mic to check them but my way works fine for a quick check

  11. #10
    Ok, i was wrong the crank if bloody fine Oops thought i was on to something.....

    next job while the cases are split i am going to change crank seals,

    but is there a trick to getting the pto coupler off? Service book doesn't say.

Page 1 of 3 1 2 3 LastLast

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. how to remove coupler from msx 140 crank
    By car22car in forum MSX/Matrix
    Replies: 8
    Last Post: 10-20-2015, 08:49 AM
  2. MSX 140 2003 will crank will not start
    By ATXMSX140 in forum MSX/Matrix
    Replies: 9
    Last Post: 06-29-2012, 12:15 AM
  3. WTB - Parts Looking for MSX 140 crank case set in ready to assemble condition
    By K447 in forum Polaris Classifieds
    Replies: 20
    Last Post: 06-20-2012, 10:33 PM
  4. 2003 MSX 140 - no spark, no display response when cranking
    By 1100zxi in forum Polaris Open Discussion
    Replies: 5
    Last Post: 06-28-2011, 10:47 AM
  5. MSX 140 crank
    By winterstick in forum MSX/Matrix
    Replies: 6
    Last Post: 06-07-2008, 07:48 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •