Honda-SOHC

SOHC.co.uk Forums => CB750 => Topic started by: zzphilzz on July 16, 2026, 10:09:56 AM

Title: Valve spring orientation
Post by: zzphilzz on July 16, 2026, 10:09:56 AM

I'm in the process of doing a top end refresh on my mates CB750 K6. On examining and stripping the cylinder head I found that the valve springs had been installed inconsistently - some tight coils up, others down. They are dual rate springs which I don't think are OEM for this model. They all have yellowish markings applied to them. I can't find any meaningful info on the net. Any advice would be appreciated. I would normally put the tighter coils valve side rather than cam side.

Title: Re: Valve spring orientation
Post by: Bryanj on July 16, 2026, 11:33:57 AM

Is it not in the genuine manual found in Ashs dropbox?

Title: Re: Valve spring orientation
Post by: taysidedragon on July 16, 2026, 01:02:14 PM

IIRC the tighter coils go on the bottom(valve side) on the 400f so 750 would most likely be the same.

Title: Re: Valve spring orientation
Post by: honda-san on July 16, 2026, 09:24:04 PM

Tighter coils against the cylinder head, definitely.

Title: Re: Valve spring orientation
Post by: K2-K6 on July 17, 2026, 09:18:14 AM

Conventional approach, unless specifically instructed otherwise, the spring mass is greater at the tighter wound end (softer part of progressive spring) that beneficial to be placed at the most static point in assembly next to head casting.

My understanding is that it makes no difference to spring rate operation, it'll compress the softest part first whichever direction fitted. But, the harmonic characteristics are fundamentally shifted when mounted with increased mass located at the most moved part, that at  valve cap/collar which offers most benefit in valve train attribute for being as lightweight as possible.