Page 1 of 3 1 2 3 LastLast
Results 1 to 10 of 29
  1. #1

    Join Date
    Jan 2014
    Posts
    19

    1968 CB350 Top End Rebuild

    Hi all, first post on the forum.

    I am tearing down an original CB350 motor with less than 2,500 miles on it. I've removed the valve cover and cylinder head, but cannot seem to get the cylinder block off of the bottom end/pistons. According to the service manual the cylinders should just lift up off of the pistons, am I understanding that correctly? If so, how can I get this thing unstuck? I've tried smacking it with a rubber mallet on various parts that aren't finned, and it won't budge. I've heard I can't try to pry beneath the fins or they'll break. Any tips?

  2.  

  3. #2
    Super Moderator longdistancerider's Avatar
    Join Date
    Oct 2011
    Location
    Lake California, California (text 408-239-9580)
    Posts
    11,768

    Re: 1968 CB350 Top End Disassembly

    Moved to 350 Engine section
    Welcome aboard
    We'd appreciate a post over in "Member Intro's" to let everyone know a bit about you and the bike. Pictures are always good to see Might even stick a pin in the Member Map and see where everyone is.
    I'm not terribly familiar with this engine but There are a couple of non obvious bolts or screws that need to be removed. Some one more familiar should be along to help out. Do you have the FSM? factory service manual?
    Jim O'Brien
    1979 CM400T "road bike" modified for travelling
    Road Trip http://www.hondatwins.net/forums/11-...here-i-go.html or "where's Jim now?"
    Member Map http://www.hondatwins.net/forums/dcMembermap.php

  4. #3

    Join Date
    Jan 2014
    Posts
    19

    Re: 1968 CB350 Top End Disassembly

    I have the FSM as a PDF on my computer. As far as I can tell it doesn't address any additional steps, if the cylinder head comes off then evidently the cylinders should too. I've posted in the members intro section with a couple of pictures, thanks for the advice! I hope somebody will have an idea for me.

  5. #4
    Supporting Member
    Join Date
    Oct 2011
    Location
    Denver, CO
    Posts
    121

    Re: 1968 CB350 Top End Disassembly

    I used a heavy duty paint scraper like this to gently pry the cases apart.

    [attachment=0:6oa6b5hu]c964ca3c-9fcf-40f3-8606-0f356f1199fe_1000.jpg[/attachment:6oa6b5hu]

    Where in Colorado are you living?
    Attached Images Attached Images  
    1969 CB160
    1972 CL350

  6. #5

    Join Date
    Jan 2014
    Posts
    19

    Re: 1968 CB350 Top End Disassembly

    Quote Originally Posted by DenverDon
    I used a heavy duty paint scraper like this to gently pry the cases apart.

    [attachment=0:31n5ulix]c964ca3c-9fcf-40f3-8606-0f356f1199fe_1000.jpg[/attachment:31n5ulix]

    Where in Colorado are you living?
    Where did you pry at? I can't find a lip to grab onto and pry up on, other than the fins.

    I'm living in Loveland!

  7. #6
    Supporting Member
    Join Date
    Oct 2011
    Location
    Denver, CO
    Posts
    121

    Re: 1968 CB350 Top End Disassembly

    I pried at several places along the cylinder gasket. It was on a cb160 but it should be similar on a 350.
    1969 CB160
    1972 CL350

  8. #7

    Join Date
    Jan 2014
    Posts
    19

    Re: 1968 CB350 Top End Disassembly

    There isn't enough space for me to get anything between the surfaces, not even a similar paint scraper.

  9. #8

    Join Date
    Jan 2014
    Posts
    19

    Re: 1968 CB350 Top End Disassembly

    Success! The cylinders are now off. I found another thread that suggested using a thin metal paint scraper which I don't have around the house, but that gave me the idea to use something of similar thickness, a butter knife! I was worried about marring up the surfaces but careful placement on the gasket avoided any big issues.

  10. #9

    Join Date
    Jan 2014
    Posts
    19

    Re: 1968 CB350 Top End Disassembly

    The cylinder head, cylinders, and pistons have been dropped off at the local machine shop. They likely won't get to any of it until next week. At the minimum the parts will be cleaned, cylinders honed (probably won't need bore, they're cherry), leak test done on the valves. Depending on how much room we have to work with, it was suggested to me that we perhaps deck the head a little bit to bump up compression. Will keep this thread updated as I do more!

  11. #10
    Super Moderator
    Join Date
    Apr 2010
    Location
    Annapolis, MD
    Posts
    4,720

    Re: 1968 CB350 Top End Disassembly

    a leakdown test is done on a fully assembled engine by filling the cylinders with compressed air at TDC and measuring the percentage of air that escapes past the rings and valves.

    you are presumably doing a leak test to see if a thin liquid seeps past your valves.

    sorry to quibble over terms...
    CB350 K5 - Uber Café- Engine build 3
    CL350 K4 - Cafe build done waiting on final assembly
    CB350 K0 - Full restoration w/Hondaline bags & fairing
    SL350 K2 - Bubba Shobert flat track build on deck
    CB-1 400F - unrestored mint rider
    2012 Guzzi V7 Racer - Daily Ride

Page 1 of 3 1 2 3 LastLast

Links

Posting Permissions

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

Search tags for this page (caching method: table, memcache)

cb350 honda valve guide removal

,
cb350 top end inspection
,
cb350 top end leak test
,

cb350 top end rebuild

Click on a term to search our site for related topics.