Racing valve springs? (or not)

[fastdruid]

Finally getting a round tuit I took a look with regard to fitting the JHS cams I have, on measuring them though it appears that they are the "stage 3" cams

The inlets appear to be 0.7mm more lift than pointy inlets and according to http://forums.sv650.org/showthread.php?t=55203 should be fitted with race springs.

Seeing as the JHS racing SV650 'archive' which might supply some more info is no more, what say those that have more experience, get and fit race springs[1] or "WTF dude, just fscking fit them".

If its "get some" then anyone got any better suggestions than the ones from TWF[2]?

Druid

[1] Which may take some time, still it appears I have 4 inlets anyway so not all is lost.
[2] http://www.twfracing.com/PartsPages/ValveSprings.html

0.7 mm is quite a lot in terms of cam design, there is a chance that the stock springs could get coil bound and the dynamics could get a bit mental.
An good indication is to look at the cam durations if you can, if they are similar then kit springs would be a good idea, if the race cams are much longer duration you might get away with it.

Rgds,
Pete

[fastdruid]

I've been told by someone that JHS played with duration etc on them as well but don't know by how much.

From another POV they have 1.3mm extra (intake) and 2.6mm (exhaust) over stock!

Druid

We use stock valve springs on all our bikes from the mild tuned 650cc bikes right through to the 750cc stroked big bore bikes with no issues at all. The stock springs are very good IMHO.

[fastdruid]

Interesting, what kind of cams are you running on them?

Druid

Kent cams to our own spec to suit a higher rev limit. Not sure on the specs, steve isnt around at the moment

[fastdruid]

I'd be interested to know the lift[1] to see if its a valid comparison, by PM if you'd rather keep it private.

Druid

[1] Although lift is not everything I don't expect you to give me exact timings, durations etc (and I wouldn't know what to do with them even if I had them! )

PM sent