Heavy Duty Valve Springs Z1-KZ900 for stock cams

Before I assemble the head, can I use a set of used heavy duty valve springs on a stock Z1-KZ900 head with stock cams?
The springs are about an 1/8 taller than stock springs.

Marty

what size are the springs and what did they come out of?
if they came out of a dragbike i probably wouldnt reccomend it

Why, is there some performance gain you seek to achieve, or are they the only springs you have available? Ed

No performance gain.
Just preventing a bent valve, from a missed shift or over rev.
I have plenty of springs from old heads.
I bought these from "oikjohnson" from Ohio on ebay. $9.99.
They have a free lenght of 1.625 inch.
Stock springs measure out at 1.550 inch.
.075 inch taller.
Just thought it would give a nice crisp, tight sound.
And knowing at least they are better than old stock springs.

Diameter, inner and outer the same.

Do a compression load check on the springs. If they are too stiff, they can cause premature ware on the valves. I agree that your old springs should be replaced. Springs get tired with time. Stiffer springs will increase your potential redline. Put those springs on a spring load tester, compress them and see what the compression load is. I would never buy used springs unless I knew what the original specs of them was and how long they were installed and what they were used for.