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Author Topic: Checking the valve timing on a 400.  (Read 12198 times)

Offline McCabe-Thiele (Ted)

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Checking the valve timing on a 400.
« on: April 03, 2022, 04:57:39 PM »
Whilst working on my timing this afternoon I briefly got confused with where TDC is I started to use the 1-4 double mark on the right instead of the "T" on the far left.

That got me thinking if I could have made a similar mistake when I fitted the camshaft in place - I probably did not but I am concerned enough to need to double check.

Is it possible to check the valve timing without having to remove the top cover?
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Offline Bryanj

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Re: Checking the valve timing on a 400.
« Reply #1 on: April 03, 2022, 05:30:20 PM »
Yes Ted, remove the tappet caps from the cylinder by the timing marks and rock the engine backwards and forwards over the T mark whilst observing the rocker arms, on one tdc they will not move(compression stroke) on the other (one turn of crank=1/2 turn of cam) the rockers will each move up and down an equal amount ( exhaust stroke tdc)


Hope that makrs sense
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Offline McCabe-Thiele (Ted)

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Re: Checking the valve timing on a 400.
« Reply #2 on: April 03, 2022, 05:57:58 PM »
Perfectly thanks Bryan.
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This is a neat 500 restoration in the USA.
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Offline McCabe-Thiele (Ted)

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Re: Checking the valve timing on a 400.
« Reply #3 on: April 05, 2022, 02:07:46 PM »
Well despite feeling crap I decided to check if my valve timing is as it should be.
Firsty with number 1 cylinder on Tdc I moved the engine forwards and backwards over the T mark neither moved. I then rotated the engine a half turn (2-3 T mark) I only observed movement on number 1 exhuast - number one inlet did not move.

Looks like I've messed up Bryan so I will need to get it sorted groan........it was going so well.
« Last Edit: April 05, 2022, 02:15:06 PM by McCabe-Thiele (Ted) »
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Link to my full restoration http://www.sohc.co.uk/index.php/topic,23291.0.html
This is a neat 500 restoration in the USA.
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Offline Bryanj

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Re: Checking the valve timing on a 400.
« Reply #4 on: April 05, 2022, 03:19:44 PM »
NO you dont check on 2/3 you both checks on 1/4 one at tdc comp one at tdc exhaust
You should move the CRANK one full turn which moves the CAM 1/2 turn
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Offline McCabe-Thiele (Ted)

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Re: Checking the valve timing on a 400.
« Reply #5 on: April 05, 2022, 04:49:11 PM »
Okay (again) the first thing I checked was with No:1 at Tdc on compression - both valves were shut with the right tapett clearance - rocking either side of "T" no movement at No1 rocker.

Tomorrow I rotate the engine one complete turn to look if both No:1 arms move at the same time one up one down when repeating the rocking at "T".
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Honda CB400NA Superdream (current money puddle)
Honda CB500 K1 (second money pit)
https://www.sohc.co.uk/index.php/topic,28541.0.html
Honda CB400 four super sport (first money pit)
Link to my full restoration http://www.sohc.co.uk/index.php/topic,23291.0.html
This is a neat 500 restoration in the USA.
http://forums.sohc4.net/index.php/topic,151576.msg1731556.html#msg1731556

Offline McCabe-Thiele (Ted)

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Re: Checking the valve timing on a 400.
« Reply #6 on: April 06, 2022, 07:43:19 AM »
All work stopped - last night we both tested positive for Covid. My temp is 102F.
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Honda CB400NA Superdream (current money puddle)
Honda CB500 K1 (second money pit)
https://www.sohc.co.uk/index.php/topic,28541.0.html
Honda CB400 four super sport (first money pit)
Link to my full restoration http://www.sohc.co.uk/index.php/topic,23291.0.html
This is a neat 500 restoration in the USA.
http://forums.sohc4.net/index.php/topic,151576.msg1731556.html#msg1731556

Online K2-K6

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Re: Checking the valve timing on a 400.
« Reply #7 on: April 06, 2022, 08:09:42 AM »
Oh no ! Hopefully you'll get these symptoms and nothing more serious as it seems to be running through this iteration of it.

Best wishes for you and Mrs Ted.
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Offline Nurse Julie

  • 1977 CB550/4 Mongrel Brat. 1974 UK 500/4 K1. Honda CD250u.
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Re: Checking the valve timing on a 400.
« Reply #8 on: April 06, 2022, 08:53:15 AM »
I hope you both feel better soon Ted.
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Offline Rozabikes Tim

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Re: Checking the valve timing on a 400.
« Reply #9 on: April 06, 2022, 09:03:33 AM »
Take care both of you.
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Offline smoothoperator

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Re: Checking the valve timing on a 400.
« Reply #10 on: April 06, 2022, 09:45:44 AM »
Put your feet up Ted and take it easy, the bike will wait for you. Get well soon.
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Offline Laverdaroo

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Re: Checking the valve timing on a 400.
« Reply #11 on: April 06, 2022, 10:35:53 AM »
Go steady, and Mrs Ted

Get well soon mate.
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Re: Checking the valve timing on a 400.
« Reply #12 on: April 06, 2022, 11:38:21 AM »
Take it easy Ted, hope you both feel better soon.
Steve P
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Offline Johnny4428

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Re: Checking the valve timing on a 400.
« Reply #13 on: April 06, 2022, 12:04:33 PM »
Yes indeed! Rest, feet up, hope your symptoms are not too bad. Get well soon.
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Offline taysidedragon

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Re: Checking the valve timing on a 400.
« Reply #14 on: April 06, 2022, 12:09:06 PM »
Get well soon Ted, and the boss! 🤒🙂
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Gareth

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