valve spring mods

Thanks for the pics Tolis
Did you put the homemade washer on the bottom? Could you weld a washer to the Husaberg washer and then mill it down to proper height?
Thanks

Hi Tolis,

The free standing height of your new spring set bears no resemblance to the old spring height. They are designed to give a fixed pressure when actually fitted, also this is when you take the deck height measurement.
By putting in your spacer you could now have to much pressure when assembled.

Regards

Sparks.

sparks,
I have a question: the cilindrical valve spring was used in the motcross versions (KTM & Husaberg) together with the much lighter titanium valves.

How would this be afeccted by using these springsets with the heavier steel valves?
Is there a risk of damage on high refs? valves touch the piston?

Cheers,Adriaan

PS
Part number Name
80036028044 VALVE SPRING KIT CPL. 05

I don't actually know what is meant with complete: just one set of springs (2) + caps
or for all four valves. But very likely not because of the price: € 136,-

dustbite said:

sparks,
I have a question: the cilindrical valve spring was used in the motcross versions (KTM & Husaberg) together with the much lighter titanium valves.

How would this be afeccted by using these springsets with the heavier steel valves?
Is there a risk of damage on high refs? valves touch the piston?

Cheers,Adriaan

PS
Part number Name
80036028044 VALVE SPRING KIT CPL. 05

I don't actually know what is meant with complete: just one set of springs (2) + caps
or for all four valves. But very likely not because of the price: € 136,-

Click to expand...

Hi Dustbite,

I wasn't aware that the Fc450 used conical valve springs, I thought the dual valve springs were fitted as standard along with the titanium valves, the titanium valves also run different seats to accompany the valves.

Regarding the valves touching the piston, we're not talking mega rpm here and if you are running the standard cam the valve to piston clearance is not that close.

I'm running dual valve springs from Kibblewhires which are for the KTM. But i must admit the kit came with what looks like thicker spring seats to what is on the photo Tolis has put up.
Put the springs straight in and the spring height measured bang on to the measurements on the packet.

Regards

Sparks.

The conical springs are designed for 36mm installed length. Their spring ratio gives appr. 38-40kg force at installed length and at max lift the spring force increases to appr. 110-120kg. This is giving a spring ratio in the region of 78kN/m which is designed to cope with a valve train (taking into account things like accelerations, speed, jerk/clearance, bounce and float) incorporating intake valves weighing 47-48 grams and concave flanks on the cam lobes. There is more to valvetrain design than making the springs fit physically...

I have just scraped the surface of this subject along the way of producing a cam of my own. I consider myself being in the state between the initial "Believing to grasp the whole idea" and the final "Comfortably knowing what I'm talking about", which is "I'm on very thin ice here". :?

Hi Dr_c,

I had a hunch there must be more to it than just fitting it in physically.

But do you think that by using the cylindrical springs there might arise a problem when the revs go up in the high regions?
With my bikes I have many failures of both the conical springs and the cam follower rollers.
With the 5 KTMs I used before I never had any problems and the rocker arms and valves are the very same parts.
First I blamed it to the splash lubrication of the cilinderhead parts but than I came across Taffy's set of cylindrical valve springs and his explanation. And it made perfectly sense to me. But then again, an engine is designed for a certain power and rpms and the force needed to close those valves is therefor fixed, isn't it?

What's the advantage of a conical spring versus cylindrical? Is it just weight & space savings?

can you shine your light on this matter?



Cheers, Adriaan

The concave shaped open/close ramps of the OEM cam lobes are said to cause high acceleration forces to the valve train. This topic has been thoroughly discussed here at UHE. It is likely that these forces are shortening the life length of the cam roller bearings. Dale Lineaweaver is providing a remedy to this with his LX1 and LX2 cams.

I need larger duration, higher lift, lobe centers further apart and less acceleration forces, which has led me in the direction of trying to produce a cam of my own. I will run the profiles #62, #53 and #08 in a "Cam Doctor" rig, to understand what is going on.

In my opinion, the conical springs' only benefits are like you say, less mass and less space required compared to a cylindrical dual spring. The conical spring gives resonance over a wider spectrum and offers no redundancy when a coil breaks.

To be able to say anything about the risk of using dual cylindrical coils together with steel valves, you need to test the springs at installed length and at max lift with a spring tester. Most well sorted tuning workshops have one.

I have not gained enough experience of my own yet, so I'd better keep my mouth shut for now.
:-#

what a load of bollocks!

jesus H.....

even a 10 year old kid could tell you lot how to sort this out.

you took the springs from a KTM right?
the ktm runs the same valves as a husaberg right?
so they weigh the same right?
and the cams are the same after '03 right?

so all you have to do is go up to a KTM cylinder head with a vernier and.....

sugar, my computer just ran out of ink!

regards

Taffy

Re:

Taffy said:

what a load of bollocks!

jesus H.....

even a 10 year old kid could tell you lot how to sort this out.

you took the springs from a KTM right?
the ktm runs the same valves as a husaberg right?
so they weigh the same right?
and the cams are the same after '03 right?

so all you have to do is go up to a KTM cylinder head with a vernier and.....

sugar, my computer just ran out of ink!

regards

Taffy

Click to expand...

lmao