Topic: Springs n things

[bwaller]

Can anyone outside of North America recommend a supplier of quality valve springs. Namely CB500 size springs.

[turboguzzi]

was going to direct you to DMS but now realize they simply sell KW sets (and out of stock anyway  )

http://www.daviesmotorsport.com/product/valve-spring-kit/

What was Gerritt, aka OldBikeTuner using in Rene's bike?

would ring his bell....

The kit i have is R&D, not S&W...BTW

http://www.rdvalvespring.com/spring-kits.html

[bwaller]

Interesting as I've checked into RD before. They actually list springs for the 500/550. Thanks TG, I'll send an email with a couple q's.
I check seat pressures every winter and shim accordingly. Usually replace them every second season, but this year some springs lost as much as 14lbs. To add enough shims to regain proper pressure would cause a coil bind issue, first time I've seen this. The thought of spring failure terrifies me so will have to change springs every season. I'm not sure if there is some change with these KPMI springs, but looking elsewhere made sense. I've never had a negative issue, but...

Then a day later I saw that Brent Hyde (captain here) experienced spring failure, dropped a valve and one chamber is a mess. In his case he was trying new springs this year and they were not up to the task, even before the engine was raced. Just proof that trying to avoid any possible weak link is imperative.
 

[turboguzzi]

I've seen that they have two kits listed, one under vintage the other under Honda. The one megacycle says to use in their catalog s is the 212, but check

[scottly]

Have you verified that the installed spring height hasn't increased? Valves sinking into the seats and valve keepers sinking into retainers, especially aluminum retainers, can increase the height, reducing seating pressure.   

[MRieck]

Have you verified that the installed spring height hasn't increased? Valves sinking into the seats and valve keepers sinking into retainers, especially aluminum retainers, can increase the height, reducing seating pressure.

All installed heights carefully checked and a fresh valve at the beginning of the season. Better quality valve seats installed as well.
The lost pressure was measured on a spring tester at a specific height (at beginning of season and end of season)....the springs yielded notably less pressure.
 I don't know.....maybe the new, younger, rider is twisting that thing a bit harder than the previous pilot.

[bwaller]

OK OK here come the old guy jokes.  There is extra stress on the engine with the younger pilot, no doubt.

There is no issue with spring base, but I'll check the Ti retainers more closely to be certain Scottly. Valve tip to retainer #'s I have. As Mike mentioned I'm anal with the spring tester and a loss of 14 lbs would need more than 1mm worth of shimming.

I've never seen this much loss after a season, actually in this case only 3 race weekends. I wonder about a change in manufacture somehow? All eight springs needed more than I've ever added post season. I'll change them every year.

I heard back from RDSprings. They prefer to sell a kit including springs, spring seats and retainers for $500+. They no longer offer Ti retainers, only aluminum, no bueno in my mind. I convinced the guy to sell me one bare spring to test.