Valve Springs question

I used these very ones on a 1978 engine with a mild lift Web Cam.

They are highly recommended by lots of folks.

Good for stock or modified engines.
 
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I'm curious to know this, too. I need some new valve springs and have heard good things about them from other members on this site... so anybody? Are these springs suitable for a stock 447 cam profile? Given, mine is rephased to 277.
 
If you want more than stock valve spring pressure with a stock cam, those will give it to you; but why would you want that? The 103-Y's are what you need with a moderate lift performance cam, but you'd better know how to inspect and set the preload ("installed valve spring height") to RD's specs. You'll need enough shims to fill the valve spring pockets up to the shoulders on the guides and to lift the spring buckets in the RD kit to the right level. Lots of washers of varying thickness, a good caliper (you'll use the depth probe), and plenty of patience are required. If you just slop 'em in there, you'll regret it.
 
Excellent, thanks for the info grizld1! I'm guessing the valve springs offered by MikesXs would have an appropriate fit with a stock cam profile then. Anybody use them before and know for sure?
 
I'd want a recommendation from a trustworthy professional before using anything from Mike's XS in a motor. You might want to shop around for NOS Yamaha parts.
 
Don't take a chance on mystery valve springs. This is not an area to try and save money. If you aren't sure they're real Yamaha parts then buy from R/D. They don't sell junk and actually know what they're doing, so you can ask questions and get real answers. Follow Griz's advice to set the heights and you'll have a trouble-free installation.
 
abyssmaltailgate said:
Excellent, thanks for the info grizld1! I'm guessing the valve springs offered by MikesXs would have an appropriate fit with a stock cam profile then. Anybody use them before and know for sure?
Click to expand...

There's nothing wrong with Mikes XS valve springs.A better choice for a stock cam or milder step up cam would be kibble white V/S on ebay or from hoos racing. You simply can't beat'em for 60.00 bucks and go with moly retainers not aluminum,also from ebay. Stock springs are garbage,even new.
 
does anyone know if you can use the kibble white springs with stock shims and retainers?

I agree with two many xs1s about proper intalation, and I just comented in another thread about buying a tool to meashure this INSTALED preshure and not just the hieghth,

I disagree that the stock springs are garbage even new, they lasted in motors that have run 30 years, and I personaly have rode the shit out of some to the limits of the engine and never had one fail, if they cant achive higher rpms that you want then that's because they wherent desighned in the first place for it,
NOTE: lol this is the first time I have disagreed about anything on this forum and I usualy don't argue with anyone, you learn a lot more from listening than from speeking IMHO ….but that's my personal opinion about factory springs, But don't get me wrong Im looking into better than factory springs for my latest 750 build with an xs1 cam, or I might just use a set of these xs1 springs I have, (yet to be detirmened if there any different from 447 spings (see my thread xs1 spings maybe))
 

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