Topic: high performance valve springs

[Mitchell]

So im about to go through my cb750 turbo motor and was thinking about putting in some aftermarket dynoman valve springs. My tthinking was that the springs will help against valve float at higher rpms, but i run a stock cam some im not so sure if its a good idea or not. So what do you guys think? I keep my rev limiter set at 9500 on an all stock motor.

[bwaller]

Compared to 40+ yr old springs, what harm can it do to have good ones? Check installed heights.

[Mitchell]

Thats what i was thinking just wanted to here some opinions. Wil the repair manual tell what the installed height should be or is there just a rule of thumb to follow

[cbr954]

My set of springs came with an installed height spec on the package.  If not just get a hold of Buzz at Dynoman and he will let you know what to set them at.

[Jerry Rxman Griffin aka MuthaF'er]

I missed a 1 - 2 power shift throttle WFO on a basically new 5000 mile stock 750F engine in '76. The valve destroyed (rather, I did) the piston then the engine. Probably close to 10,000 rpm when I missed it. 12,000 rpm perhaps? Don't know but that loud BANG totally fukd up my engine. I used HD springs on the rebuild to hopefully lessen the likelihood of it occurring again. Also did the rest of the Yoshi 812 kit too with their Daytona cam. It lasted another 25,000 hard miles until I took it apart due to age, miles and my continual abuse but no more floating but guaranteed missed shifts. 

[Mitchell]

Good in put guys you all have convinced me to use em. What if the spring height is incorrect? To low shim it? What if its to high?

[dragracer]

Good in put guys you all have convinced me to use em. What if the spring height is incorrect? To low shim it? What if its to high?

Some of the spring kits come with shims. As others said, most spring packs come with installed height info. If you're rebuilding the engine, a valve job is advisable anyway. Donald Shaw can do an excellent job on the head.

[Mitchell]

Thanks guys!!!! I still havent got with mr donald on the trans back cutting its just been to hot to get out in the shop and do anything, its been to hot to evan ride a motorcycle around here

[Big Jay]

You must remember that turbo motors have pressure on the back side of the intake valve which ther spring has to over come. Just put good springs in it. 
http://cbrzone.com/sohc.html