Logo
Click for Honda Manuals, Parts and Model Guides!
Results 1 to 9 of 9
  1. #1

    Question 2003 BF 50 - Cracked Cam Pulley (Pulser Rotor)

    Hi All,

    I purchased a 2003 Honda BF 50 with 85 hours that had a broken cam pulley for a really good deal. My intention was to use it as a spare parts motor for my 1997 BF 50. I was suspecting the broken cam pulley caused damage to the vales, heads, and piston. But after taking the heads off, everything seems to be in order - the valves are not bent, the heads are not scored, the pistons look fine. There is no warping of the block or heads, the fly wheel turns smoothly in fwd/reverse/neutral. I am guessing when the cam pulley broke, it did so at perfect timing and all valves shut and did not reopen. I am now thinking it makes sense to replace my 1997 and fix this one. Other than all the gaskets, the only true parts needed to get this running are the Cam Pulley (Pulser Rotor) and the pulser coil underneath. (I will replace a lot of other things as well if I got this route - spark plugs, anodes, impeller, thermostat etc).

    Does anyone have any ideas on what would have caused the cam pulley to break? I have never seen or heard of this before and am stumped.

    Am I overlooking something that should be checked?


    Thanks in advanced.

    Click image for larger version. 

Name:	broken ca pulley-min.jpg 
Views:	23 
Size:	449.2 KB 
ID:	22950

  2. #2
    Join Date
    Apr 2018
    Posts
    1,193

    Default Re: 2003 BF 50 - Cracked Cam Pulley (Pulser Rotor)

    I would be checking those valves very carefully, some will hit the piston, there is no such thing as all the valves being closed at once. When a valve hits the piston on a BF 50 the amount it bends is barely noticeable other than the fact that the offending cylinder will have no compression.As far as pulley breaking,perhaps fatigue,who knows. Just make sure the cam bearing journals are all okay and that the camshaft spins freely.

  3. #3
    Join Date
    Nov 2009
    Location
    temecula, ca., usa
    Posts
    3,399

    Default Re: 2003 BF 50 - Cracked Cam Pulley (Pulser Rotor)

    I agree with Ian...no such thing as all valves closed at once unless the rocker arms are backed off/removed.

    Compression test before preceding.

    Having said that, engines do jump time and valves don't always bend as a result. So, you could be lucky. And, even if you have a bent valve or two, as long as the piston tops aren't damaged, you could still have a very easily repaired engine there.

    He is also spot on about making sure that camshaft didn't suddenly seize for some reason. Check the cam bearings and journals very carefully.

    Failure analysis of the pulley would be helpful here so running it by a machine shop or two and getting opinions as to why it may have broken could be worth your while. Many machinists have good knowledge of metal failures and they usually have illustrated reference materials for figuring out component failure. It could be as simple as a manufacturing or casting flaw.

    Good luck with your project.

  4. #4

    Default Re: 2003 BF 50 - Cracked Cam Pulley (Pulser Rotor)

    Quote Originally Posted by iang6766 View Post
    I would be checking those valves very carefully, some will hit the piston, there is no such thing as all the valves being closed at once. When a valve hits the piston on a BF 50 the amount it bends is barely noticeable other than the fact that the offending cylinder will have no compression.As far as pulley breaking,perhaps fatigue,who knows. Just make sure the cam bearing journals are all okay and that the camshaft spins freely.
    Hi Ian, thanks for the reply. The valves do not appear to bent, but definitely something I will need to look at closer. Is the best/only way to check by taking the cam assembly apart? Or inspecting the valve seats when rotating the camshaft sufficient?

    For the cam bearing journals, just make sure the bearings are good and no excessive play, etc.?

    This is my first time taking the heads off any dealing with the camshaft..I do have the honda service manual though which has been very helpful.

  5. #5

    Default Re: 2003 BF 50 - Cracked Cam Pulley (Pulser Rotor)

    Quote Originally Posted by jgmo View Post
    I agree with Ian...no such thing as all valves closed at once unless the rocker arms are backed off/removed.

    Compression test before preceding.

    Having said that, engines do jump time and valves don't always bend as a result. So, you could be lucky. And, even if you have a bent valve or two, as long as the piston tops aren't damaged, you could still have a very easily repaired engine there.

    He is also spot on about making sure that camshaft didn't suddenly seize for some reason. Check the cam bearings and journals very carefully.

    Failure analysis of the pulley would be helpful here so running it by a machine shop or two and getting opinions as to why it may have broken could be worth your while. Many machinists have good knowledge of metal failures and they usually have illustrated reference materials for figuring out component failure. It could be as simple as a manufacturing or casting flaw.

    Good luck with your project.
    Hi jgmo, thank you for the input - it is much appreciated. All the piston tops do not have any markings on them at all, unlike what I was suspecting to see. I wish I swapped the cam pulley and did a compression test before removing the heads....hindsight 20/20 I guess.

    Those are very good points - that is my main concern on what might have caused this initially. I have a local machine shop I have used in the past, I will get their opinion.

    Thank you much.

  6. #6
    Join Date
    Apr 2018
    Posts
    1,193

    Default Re: 2003 BF 50 - Cracked Cam Pulley (Pulser Rotor)

    Easy way to check valves, remove the cam shaft, invert the cylinder head and fill each combustion chamber with water and check in the inlet and exhaust ports for leaks

  7. #7
    Join Date
    Nov 2009
    Location
    temecula, ca., usa
    Posts
    3,399

    Default Re: 2003 BF 50 - Cracked Cam Pulley (Pulser Rotor)

    When I used to do a lot of this kind of thing (corona danger list occupant now;>) I was really into valves sealing after lapping. I used a technique a much smarter wrench than I showed me...

    If you have the head off and rockers loose, you can prop it upside down so the valve heads are flat and then just spray some carb cleaner on each valve head until it begins to pool around the valve edge. If it stays pooled for a bit as the cleaner evaporates away, you have a good seal. If the spray won't pool or drains away quicky, you have a poor face seal and you will see the cleaner run down the stem and on to your work bench.
    This might also work for you here to find leaks.. IE: bent valves.

    The best way though, at least for a novice, is maybe take the head with you to the machine shop when you go to ask questions.

    Good luck.

  8. #8

    Default Re: 2003 BF 50 - Cracked Cam Pulley (Pulser Rotor)

    Ian, jgmo, thank you - it is much appreciated.

    I did the tests to see if the valves would leak....sure enough, cylinder #2 is leaking from exhaust and intake from both water and carb cleaner. The other valves seemed to have a good seal. But I went ahead and ordered new valves and valve seals for all cylinders.

    Question on gasket sealant...for the Head Cover gasket/packing, the service manual says use: Three Bond #1201 or #1215or equivalent. I am having troubling finding either of those. Is there an alternative typically used? Hondabond HT maybe?

    Should gasket sealant be used on the head gaskets as well?

    Any other tips, information, things to do while the heads are off, feel free to share whatever you feel like typing

  9. #9
    Join Date
    Nov 2009
    Location
    temecula, ca., usa
    Posts
    3,399

    Default Re: 2003 BF 50 - Cracked Cam Pulley (Pulser Rotor)

    No sealant on the head gasket!
    Are you working with the shop manual?
    Follow the torque instructions to the letter. Do not use lubrication on the threads unless the manual specifies lube.
    If the head bolts are TTY (Torque To Yield) you will need to use new bolts.
    Clean the bolt threads and the bolt holes in the block carefully and use compressed air to push any loose debris out of the bolt holes.


    I like to use Right Stuff sealant on water and oil gaskets. It is also an excellent gasket maker if you don't have original material gaskets.
    It doesn't work at all with gasoline though.

    With new valves I would recommend having your machinist measure the seats. More than likely the valves and the seats will need a bit of dressing to achieve a proper seal. It is well worth the expense to do this for reliable operation. Nothing is more frustrating than to put everything back together only to have misfiring on startup.

    Good luck.

Similar Threads

  1. Replacing Pulser Coil 03 DT150
    By lanes in forum Suzuki Outboard Forum
    Replies: 0
    Last Post: 09-22-2019, 10:32 PM
  2. Variable speed pulser
    By pedro76 in forum Mercury Mariner Outboard Forum
    Replies: 0
    Last Post: 10-23-2013, 11:11 PM
  3. 2003 bf 225 pistons all cracked # 4, 5 and 6
    By escape fisherman in forum Honda Outboard Forum
    Replies: 5
    Last Post: 10-16-2012, 08:19 AM
  4. Looking for a Pulser Coil BF75S
    By stairwaytoseven in forum Honda Outboard Forum
    Replies: 0
    Last Post: 02-28-2010, 08:22 PM
  5. Cracked block and repair for Volvo 2003
    By edenrose in forum Volvo Penta Diesel Archive 2004-2009
    Replies: 2
    Last Post: 02-20-2007, 10:18 PM

Posting Permissions

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