Topic: valve spring discussion?

[NitroHunter]

Yes Don I was told by Eraldo Ferracci to use the F-2 cam with my turbo due to the 108 lobe centers.

[johno]

There a good bunch of cams there, all to suit there own needs. All good for our 50 year old bikes and a retailer like cycle x that stock a spring selection to cover those needs . Not many people take the 750's to the edge these days but if you decided to do it and have some cash the cam technology has changed a lot these days with polydyne profiles for example ( I know, I know,  they have been around for 20 years but there hasn't been a market or need to produce modern cams for the ol 750's). These profiles have positive and negative ramps on them where they accelerate the valve opening so fast the spring can't control the valve so after the valve opening the cam is ground to quickly slow down rate of opening to let the cam follower stay on the cam and stop the valve from floating off into the sunset. so theoretically the cam profile is like a couple of big waves up the flanks. BUT as we all know the problem for power gains comparable to modern bikes is not the cams or springs , its the cam / valve angles and geometry that's the problem and no matter what we do were reinventing the wheel unless someone courageous like "big bore MR" has a big ticker and deep pockets to get a new head cnc'd up so we can get some serious valve timing and lift into our babies.  hehehe go Mike. yeh baby lol
cheers Johno

[gschuld]

Yes, not highest hp but reliable build feels like a good idea. But where is the limit?
- Revs only?
- Compression with ignition OK as long as no pinging?
- Beehive springs act as progressive springs?

I had to search and found info
https://www.enginelabs.com/engine-tech/engine/beehive-springs-sound-great-but-will-they-work-for-you/

CycleX has for 5mm valves only.


It would be fine to know the lowest possible spring/seat pressure.
I have a feeling that my heads have a little bit too hard setting to ensure no float but add more wear.

Springs that can make valves to survive a missed gear shift.

Need a video of an open CB750 setup with high speed camera that can show when valves goes wild.
Or which spring pressure needed for 0.400/0.375 lift, heavy valves and max 9500rpm.

To make sure there is no confusion.  CycleX does carry a beehive spring kit for OEM stem diameter valves. 

George

[Don R]

Yes Don I was told by Eraldo Ferracci to use the F-2 cam with my turbo due to the 108 lobe centers.

That's good to hear, Thank You.

  I understood the advantages to the beehive springs are the retainer is smaller and lighter, as is the moving end of the spring itself and each wind of the coil has a different harmonic rate/rpm so it sort of cancels out the slinky tendency. 

[PeWe]

.....
To make sure there is no confusion.  CycleX does carry a beehive spring kit for OEM stem diameter valves. 

George

Good news George!
I did not find it on their website.
Edit: Revisited and found
http://www.cyclexchange.net/F2%20Springs%20and%20Other%20Hardware.htm

ENV-010K for "K" models     $239.00

ENV-010F for 77-78 "F" models     $239.00

ENV-010-5MM for Kibblewhite 5mm kits     $239.00

One more thing to consider for next order.
- Any info about which type of cams/rpm area that will get best result with these springs?

I left some CB parts at my nearby tuning shop where I tried to pump him on seat pressures.

One absolute answer is difficult.
Much depending on cam  profile,  avoid airborn rocker/bounce after the lobe tip. 
Too hard springs take hp, too soft causing rocker arm airborn which take hp too
Plus eventual damage $$$

 I checked a few of my cams when back. One had less marks just after the IN tips.

The shape of Beehive springs  will make coil less prone to bind. Compress spring, the smaller wounds goes more to the inside of the wider.

Nice to have if possible...
Color the cam lobes and inspect afterwards?
Special surface coloring needed
Adjustabe retainers would be fine, turn them as a nut to tighten or loosen. No need to remove head for spring adjustment

[gschuld]

Mike would be the one to answer the spring pressures questions.

My interest in the beehives is for big bore road racing applications. 

Matt, FWIW, is running those springs on his 34/28 valve K race head on his Sportsman bike with a CX7 cam.

The CyckeX beehive springs will handle high lift.  CX10 cam is the plan going fwd on the next engine.

.430” lift on both ends.  The head needs to be set up to run extra high lift(valve to valve clearance and high lift iron guides(available at CycleX)

IMHO, quality double springs are long proven to get the job done.  That said, beehive springs are said to help reduce harmonics, reduce overall valve/spring/retainer weight, and offer better valve control at the higher end of the rpm range, especially in the over 10,000rpm neighborhood.  The high performance OEM world is all about beehive springs for a reason.

There have been some limited reports of double springs losing a noticeable (and surprising) amount of spring pressure after just one racing season.  Perhaps it’s a localized batch issue of a particular spring set, but beehive springs seem to be doing quite well in the longevity department in race engines.

The more modest the cam, and severity in intended use, the less justification for the more expensive beehive springs I’d guess.

Under say .400” lift, street engine use, it could certainly be argued that beehives are not worth the extra cost.

George

[PeWe]

Thank you very much for the details.
I saw this thread and got ideas about correct seat pressure (as low as possible), valve in control with minimum wear.
For modified street bike, longetivity.

I should have known this last summer when I ordered a complete spring set with tensioners from CycleX.

Use beehive with the 125-75 cam that is very "civilized".

It seems that seat pressure is relatively low compared to the old double springs when reading CycleX spring description.

I understand why this kind of spring is popular in high power engines and rev torturing applications if this can keep everything in control with lower seat pressure than with older type of springs.

[Don R]

 The information I get is horsepower loss/spring pressure is minimal, the spring pushes back on the ramp as much as it takes to open. My worry is wear and breakage. My racecar has 300 psi off the seat. I don't even think about the open pressure.

[Tracksnblades1]

PeWe,

Could you have a conversion kit ready in a few months..?

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwiIyKXR-Zj1AhWqlIkEHT88Dp0QtwJ6BAgFEAI&url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DjgOg55g-Hs8&usg=AOvVaw1oGAv7GRevVRiPySHBt00y

Even though I think Ducati has moved on…

[PeWe]

Yes, too complicated with the extra rocker arm. All should have it otherwise. That is valve control!
I remember that Ducati 500 Desmo was one of the bikes I looked at before I decided to buy my blue CB750 K6.

I did a quick search now to see if Ducati still use it. Found interesting history.
https://www.cnet.com/google-amp/news/desmo-valves-race-car-ducati-mercedes-motorcycle/

Finding and adjusting the best spring to fit your application is what we have.
Hopefully no longer need of bolts thru valve cover keeping the cam holders in place
 
Standard designs often begin as high tech for race.

Same with cars where granny's car can have a DOHC engine with turbo,  intercooler and electronic injection, a very old one!

[Tracksnblades1]

PeWe, What about this type ?
With a mini plc board to control regulator pressure based off of an input from an electronic or Hondaman ignition .
Plc could use the input to flag a counter to monitor rpm for a pid or preset air pressure/rpm curve. This would accomplish your goals with one rocker and just the right amount of spring pressure for the given rpm and cam profile..?
You’d be reinventing the wheel. I think GP and F1 have it already.

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwjIvMbKjZ71AhWnjIkEHbilA0cQwqsBegQIBBAB&url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DHxEiESBLF9s&usg=AOvVaw3CiXvHQFaX8hVSquaNToHW

[Don R]

 Warren Johnson asked NHRA for permission to use pneumatic springs in his pro stock engines. They said it would give him an unfair advantage, he said he would buy them for everyone in the class with his savings on springs. Still got a no.

[PeWe]

Good ideas!
Like the Swedish car manufacturer Koenigsegg, seldom seen in the mirrors except for a ms or 2!!  "What was that? Wind or an jet fighter??"

It would be fine on my bike!
I'll order the 125-75 program at the same time!
Possible to change "cam" program while riding!!