Author Topic: Engine rebuild questions  (Read 345 times)

Offline Dolomite_

  • Newbie
  • Posts: 29
    • View Profile
Engine rebuild questions
« on: February 11, 2024, 10:15:59 PM »
I've just finished stripping the engine, just the valves to do. What are the main things I should check for? The bike has done 28k miles.

I'm already planning on getting new big end bearings etc and replacing the cam tensioner and cam chain.

The primary chain seems fine. How much play should there be?

The pistons seem fine to me, how should I judge if I need to get some up sized ones?

Some of the crankcase bolts were a bit naff and one rounded off, does anyone know anywhere that does some good quality replacements?
I've found these https://www.ebay.co.uk/itm/262689167997 are allen heads fine? I cant seem to find any hex bolt sets.

Offline Athame57

  • SOHC Master
  • Posts: 1058
    • View Profile
    • SeaWitch Artist
Re: Engine rebuild questions
« Reply #1 on: February 11, 2024, 10:56:18 PM »
If a primary chain is stood upright and the top half sags enough to make contact with the bottom half its time to change.
I brake for animals!
1978 CB400F2

Offline Nurse Julie

  • 1977 CB550/4 Mongrel Brat. 1974 UK 500/4 K1. Honda CD250u.
  • Grogu
  • *
  • Posts: 8144
    • View Profile
Re: Engine rebuild questions
« Reply #2 on: February 11, 2024, 11:03:04 PM »
Knackered Vs new

[ Guests cannot view attachments ]
LINK TO MY EBAY PAGE. As many of you know already, I give 10% discount and do post at cost to forum members if you PM me direct.
https://www.ebay.co.uk/sch/julies9731/m.html?item=165142672569&rt=nc&_trksid=p2047675.m3561.l2562

LINK TO MY CB400/4 ENGINE STRIP / ASSESSMENT AND REBUILD...NOW COMPLETE
http://www.sohc.co.uk/index.php/topic,14049.msg112691/topicseen.html#new

Offline Bryanj

  • Grogu
  • *
  • Posts: 10600
    • View Profile
Re: Engine rebuild questions
« Reply #3 on: February 11, 2024, 11:34:07 PM »
Shells rarely need changing, Julies picture is of a useless chain and it you fit new also chage rubber dampers in primary drive.
Check tensioner horseshoe for free movement and tensioner lock bolt ans plunger

Offline Matt_Harrington

  • SOHC Pro
  • Posts: 815
    • View Profile
Re: Engine rebuild questions
« Reply #4 on: February 12, 2024, 08:26:36 AM »
Westfield fasteners will do most of what you want (there is another supplies but I can't think of them on a Monday morn!)
I'd replace the camchain as well.
As Bryn says, unlikely shells need changing. Check if the cylinder bore look OK and if there is a lip at the top.
Matt
___________________________________
CB400F 1976 -  Almost finished
CB400F 1977 - On the road!
Moto Guzzi T4 - 1981 - My tourer (plus a loft full of spares)
Moto Guzzi Le Mans 2 - 1981
Triumph 3T - 1947 (somewhat dismantled!)
CD175 - To be restored

Offline Bryanj

  • Grogu
  • *
  • Posts: 10600
    • View Profile
Re: Engine rebuild questions
« Reply #5 on: February 12, 2024, 08:41:19 AM »
Primary chain use kawasaki, many posts on that for part number

Offline Dolomite_

  • Newbie
  • Posts: 29
    • View Profile
Re: Engine rebuild questions
« Reply #6 on: February 12, 2024, 09:06:01 AM »
Shells rarely need changing, Julies picture is of a useless chain and it you fit new also chage rubber dampers in primary drive.
Check tensioner horseshoe for free movement and tensioner lock bolt ans plunger

The tensioner horseshoe is seized so thats being replaced. The tensioner lock bolt and plunger need repairing, I'm taking the crankcase today to see if it can be repaired as I'm not confident that I could drill and tap the new thread.


Offline Dolomite_

  • Newbie
  • Posts: 29
    • View Profile
Re: Engine rebuild questions
« Reply #7 on: February 12, 2024, 09:09:08 AM »
Westfield fasteners will do most of what you want (there is another supplies but I can't think of them on a Monday morn!)
I'd replace the camchain as well.
As Bryn says, unlikely shells need changing. Check if the cylinder bore look OK and if there is a lip at the top.

Is there a list of the bolts required? I was trying to find a crankcase set so I know I've got the correct bolts. Westfield fasteners just seem to do individual and I dont want to get the wrong bolts  :D


Offline Dolomite_

  • Newbie
  • Posts: 29
    • View Profile
Re: Engine rebuild questions
« Reply #9 on: February 12, 2024, 09:23:50 AM »
There is a fix for the adjuster that has an O ring fitted its a SS unit that requires the original thread to be tapped out.

It is similar to this one - my old purchase supplier is no longer listed mine was about £25.00

https://www.ebay.co.uk/itm/254365035879?fits=UKM_Make%3AHonda&hash=item3b39566d67:g:IaIAAOSwJdBdgzyv&amdata=enc%3AAQAIAAAA8EghuxUfhrhh6U3vmNEX4HnoPUWzZ%2FPzRruuHgaJJ9NT87T7myJXmZF00bygB1jwfGKOFG6A1FJrvAbkO7fMWIJeZSwLgQMsU6azrhsN2G%2FMp0KE%2BKuDXRVwTYw1aQdoYHweSPTSUnQUjqZh4%2BkLI6Zqj%2FXfMGUNdngSUwikIjpG6W%2B90vxeVMv15KShH8iZJLY3fwWwD9NQdaTv0O6SjoUE4TviOvYWkcvIn7Q6vssC%2Bsu2mAR8Yk7R5kk%2Be7mHn8K1M3cplTNQ7q0GZpQgzit6XaeRfImXKLyaDudyIpcNTRpN4tw%2BC9rpSx%2BNzoMyNA%3D%3D%7Ctkp%3ABk9SR_z5ycmzYw

I've got the replacement one where you need to tap out the original thread. But it looks like the previous owner did such a bodge job it cant just be tapped out. It looks like the original thread is there and someone has tried to drill it at an angle.

Offline McCabe-Thiele (Ted)

  • Grogu
  • *
  • Posts: 5847
    • View Profile
Re: Engine rebuild questions
« Reply #10 on: February 12, 2024, 09:26:14 AM »
A good engineering shop might be able to fit an alloy plug and sort it out - I had to do similar on one of my fork legs.
Honda CB500 K1 (new pit dug out ready)
Honda CB400 four super sport (first money pit)
http://www.sohc.co.uk/index.php/topic,23291.0.html

Offline Bryanj

  • Grogu
  • *
  • Posts: 10600
    • View Profile
Re: Engine rebuild questions
« Reply #11 on: February 12, 2024, 04:38:35 PM »
I think the firm is noxandrattles that does a ki with an oversixed bush to fit in crancase

 

SimplePortal 2.3.5 © 2008-2012, SimplePortal