The 'Correct' method to adjust the 400/4 cam chain tensioner?

[Laverda Dave]

I have just read this interesting piece on the Mike Nixon Motorcycle Project page:

'The correct procedure is to remove the bolt serving as a sealing plug on the plunger. Then put the crankshaft at TDCC (compression) on the #4 cylinder. Insert a Phillips screwdriver into the hole the plunger resides in and while pushing with moderate pressure, loosen the tensioner locknut and lockbolt, rotate the crankshaft 10 to 15 degrees, and snug the lockbolt and locknut. Release pressure on the plunger and replace its sealing bolt. This is the correct way for the CB350F, CB400F and CB/CL360. Don't use any method that includes running the engine.'

The above was the method I was told to use back in the 1980’s to adjust the tensioner but only if after adjusting the tensioner in the ‘normal’ way as described in the Haynes manual with the engine idling at a steady 1200RPM there was no difference in the sound of the engine indicating the tensioner arm was sticking (a sure sign of damage to the pivot point caused by a slack cam chain eating into it and also potentially into the top crankcase ).

So the question is who is right and what methods are used by the 400/4 collective on the forum?

[McCabe-Thiele (Ted)]

FWIW when I was rebuilding my 400 I had number one cylinder at TDC whist using a spanner to take up the slack to the point just before the engine startes to rotate , this I was told means the chain is effectively taught then nipped up the pinch bolt.

Back in the 1960's on my 250 Dream I used the method with the engine running that you described. I do not like the idea of pressing down on the tensioner mechanism with a rod or Phillips screwdriver - might be an option of the horseshoe is starting to stiffen up though.

[Alexrayz]

For reference I use the revue technique moto for the Honda CB400F and Norton Commando.
They do say to use the idling engine method.
What I have read elsewhere is that if your horseshoe is binding or the spring is old the conventional method doesn’t work, as there is too much resistance for the spring and stem bit to set the slack correctly.
The fix is to use the « engine off , screwdriver inside » that you described.

I don’t have the shop manual right now, maybe there is something on there?

Anyway here was the information I have. I need to adjust the chain soon so I’ll keep an eye out

[Bryanj]

Using a screwdriver usually overtightenes the camchain leading to excessive wear and possible breakage, ifthis is the only way you can doo it then something is broken/siezed and needs fixing