Results 1 to 7 of 7
  1. #1
    CB750 New Member itcan's Avatar
    Join Date
    Mar 2015
    Location
    Cape Town, South Afriuca
    Posts
    2

    Noisy Primary Chain

    I have a 1981 Honda CB750F. When starting the engine, there is a knocking sound coming from the center of the engine - in the area near the starter motor mounting bolts. On inspection, it appears that the Primary Gear Chain Tensioner is worn. I could not find a new tensioner and the part is no longer available through Honda. I then reassembled the engine - correctly to spec. Upon starting up again the noise has increased. If you rev the engine, the noise goes away at about 2000 RPM. To my mind, it seams like the increased RPM increases the oil pressure and thereby increases the Primary Chain Tension. Or am I wrong in my diagnosis? Any idea where I can get a new Primary Chain Tensioner?

  2. #2
    CB750 New Member itcan's Avatar
    Join Date
    Mar 2015
    Location
    Cape Town, South Afriuca
    Posts
    2
    Seems like this is a sleepy forum or my problem is too technical!!
    I stripped the engine completely and found the inlet and exhaust timing chain tensioners to be finishes. In addition, four of the exhaust valves are slightly bent and one valve cotter is missing. So.... anybody know where I can get timing chain tensioners, exhaust vales and a cotter from?

  3. #3
    CB750 Enthusiast Motorhead's Avatar
    Join Date
    May 2016
    Location
    Israel
    Posts
    51
    My source of parts was always davidsilverspares.co.uk.

    Sent from my A0001 using Tapatalk

  4. #4
    CB750 New Member Bradplaysguitar's Avatar
    Join Date
    May 2018
    Location
    Victoria, BC
    Posts
    1

    Engine noise

    Quote Originally Posted by itcan View Post
    Seems like this is a sleepy forum or my problem is too technical!!
    I stripped the engine completely and found the inlet and exhaust timing chain tensioners to be finishes. In addition, four of the exhaust valves are slightly bent and one valve cotter is missing. So.... anybody know where I can get timing chain tensioners, exhaust vales and a cotter from?
    Hey did you ever solve your problem? I think Iím having the same issue on my 1981 cb900f

  5. #5
    Old Bike Nerd grepper's Avatar
    Join Date
    Oct 2012
    Location
    Lowell, MI
    Posts
    460
    The tensioner on the Primary change runs off of oil pressure, so they can get noisy at low idle. Sometimes just syncing the carbs will smooth is out, as a smoother running engine will produce consistent oil pressure.
    Drive fast and take chances

  6. #6
    CB750 Addict Skelee's Avatar
    Join Date
    Nov 2017
    Location
    Hamilton, Canada
    Posts
    138
    Some sites for parts
    4 to 1 honda
    Cb750 supply
    Fortnine
    Dime city cycles

    Have you adjusted the cam chain?

    Sent from my SM-A520W using Tapatalk

  7. #7
    Old Bike Nerd grepper's Avatar
    Join Date
    Oct 2012
    Location
    Lowell, MI
    Posts
    460
    As far as buying new tensioner parts, oem is hard to find. Here's an alternative
    https://www.google.com/url?sa=t&sour...6QGxSL2HZiGne2

    Sent from my XT1254 using Tapatalk
    Drive fast and take chances

Similar Threads

  1. Linkless chain????
    By marty shawn in forum The SOHC Garage (1969-1978)
    Replies: 2
    Last Post: 02-17-2015, 09:49 AM
  2. Noisy chain
    By Cargos in forum The CB750 Garage
    Replies: 0
    Last Post: 07-22-2014, 10:38 PM
  3. Chain lube
    By dan1951 in forum The CB750 Garage
    Replies: 4
    Last Post: 07-22-2014, 07:14 AM
  4. Chain mismatch help
    By RedSchmutz in forum The CB750 Garage
    Replies: 6
    Last Post: 10-19-2013, 12:07 AM
  5. Chain conversion
    By K2750tracy in forum The CB750 Garage
    Replies: 5
    Last Post: 11-19-2012, 10:51 AM

Tags for this Thread

Posting Permissions

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