Valve Tuliping

Parsko · Apr 27, 2004

I have read plenty of posts here in the past regarding this topic.

What exactly is tuliping?

Can someone explain this in as much detail as possible?

My guess:
when the valve spring forces are too high, the valve will want to bury itself further into the valve seat, hence causing it to "close up" on itself like a flower??

I have also heard about 2 piece valves (which to me sounds like a ludicrous idea). Which bergs came with these, if any?

-Parsko

PowerFiend · Apr 27, 2004

Parsko said:
My guess:
when the valve spring forces are too high, the valve will want to bury itself further into the valve seat, hence causing it to "close up" on itself like a flower??

-Parsko

Yes, but it is not necessarily due to to strong a valve spring force. Valve springs should be strong enough so that the valve follows the cam for its entire open time and across the entire available designed rpm range. To strong a spring and it is overkill and can wear on the valve train, to weak and you get valve float(Valve doesn't follow cam, but floats away. Said to be the issue with CRF's breaking valves). The Berg's problem from the way I understand it is that the cam profile lets the valve accelerate to quickly to close, thus the valve gets pounded into the seat and causes it to form into a tulip shape. If the cam has a slower closing speed, ala a Lineaweaver cam, it allows the valve to close with a more resonable and acceptable force.

Taffy · Apr 27, 2004

valves are made using the toughest and meanest form of welding known to man-friction welding. the dogs knee-caps!

there isn't a lot wrong with the valves that an unlimited bank balance and that rarest of all metals-unobtainium-wouldn't cure!

Taffy

dave186 · Apr 27, 2004

when a valve is tuliped, the face goes from looking like this / \
to more like this ) (

well sort of, maybe you get the idea.

Parsko · Apr 27, 2004

Yeah, friction welding is a great technique, greatly underappreciated! I am pretty sure that the major fitting suppliers (Parker/Swagelok/etc...) use this technique for many applications. This is how they make valves??? Where is the split located on the valve, near/at the transition from shaft to "cone"?

I see. So the valve will somewhat fold into itself? Is this physically noticable, or does one have to measure? Is it curable by lapping? Or would one need new valves?

dave186 · Apr 27, 2004

that wasnt a good illustration. I had some CRF 450 Ti valves that were tuliped beyond belief, but the owner took them with him.

the top pic is a brand new stainless steel intake valve, the bottom pic is photoshoped, thats pretty much what a tuliped valve looks like.

justin_yz426 · Apr 27, 2004

2 piece valves are crap! Stay Away!! I had an intake valve break on my 426 at about 8 grand in 4th gear at about 65 mph. I nearly flew over the bars. If it werent for my 320 pounds I would have. It destroyed the motor. Thats why they run titanium valves now. But Those are bad because they destroy valve seats.

dave186 · Apr 27, 2004

justin_yz426 said:
Thats why they run titanium valves now. But Those are bad because they destroy valve seats.

how does that work? the CRF Ti valves are softer (once the coating wears off) than the seats they use so they usually survive. Maybe the yammys are different?

Taffy · Apr 27, 2004

and replace the husaberg valves with ti what from where?

Taffy

justin_yz426 · Apr 28, 2004

They are much, much harder then the valve seats. So they pound them in and wear them out quick. Thats why racers who build motors will not use them. Unless they want to replace valve seats and do a valve job offen.

Parsko · Apr 28, 2004

The logical solution to that would be Titanium seats, right? Or, is there a CTE issue between Al and Ti that would not allow this?

justin_yz426 · Apr 28, 2004

I couldent answer that one. I dont think they make ti seats just jet.

Parsko · Apr 28, 2004

Yes, there might be some CTE issues. Al about 14 microns/in. Ti about 5 microns/in. That's a factor of almost 3. Seats are pressed in, I assume. Though, the right press fit would do the job.

Cost... Ti way more than steel. Way way more. So much more that I would personnaly rather deal with the wear, and replace.

Man, I wish work would end, I want to ride when I get home........

JoeUSA · Apr 28, 2004

Taffy said:
and replace the husaberg valves with ti what from where?

Taffy

Taffy,

Check with your KTM dealer, he may be able to get you factory Ti intakes . I have no idea as to the cost though. I am running KTM intakes in my Berg (bergs were on back order) but they are the stock KTM OEM valves, not Ti.

Joe

justin_yz426 · Apr 28, 2004

I belive ti holds it's shape. From what i'm told. I may be wrong on this. If your ti valve is hot and somthing happens in the motor. And it bends, it will go back to it's original shape. So if that is true then I dont think it could be pressed in. But I may be wrong on this.

Taffy · Apr 28, 2004

joe

i was being rhetorical. somebody was talking from a hole about their persons.

Taffy

LINEAWEAVER · Apr 28, 2004

Titanium and Stainless are both compatible with the majority of OEM seats providing proper valve motion is insured. (ie realistic RPM, correct camshaft profile and proper valve spring rates).

Many CRF valve recession issues are as a result of operator error.
The rev limiter is not to be used as a shift indicator.

Kind Regards,
Dale

Ps
Husaberg valves of either material are made to order.

Parsko · Apr 29, 2004

Dale, my first reaction to that is....

NO KIDDING!!!!

I'm not trying to be a pr#ck either!

After seeing the HP curves posted on anther recent thread, if one is revving past around 8500, they are well past the power band, and ONLY at risk of hurting the motor.

Side note: A buddy of mine has a Formula Ford race car. I spend quite a bit of time chewin' the cud with him about this. Tuesday he spent about 1.5 hours on a dyno (only cost him $85!!!!!!!!!). Prior, he was under the impression that his motor produced power between 7-8ish. NOW, he knows that the power starts at 5.5 and goes to around 7. This new knowledge will change both his setup and driving style, thus making him more competitive. Getting back to how this correlates... he doesn't need to beat the p#ss out of his motor now that he has knowledge of how it performs. I think this is true of many a person out yonder. Most people don't realize (especially in the case of the mad low-end torque of the berg) that the top 10-20% of the theoretical RPM range is useless, unless you are specifically tuned/setup for it.

Agree?

LINEAWEAVER · Apr 29, 2004

Parsko said:
....
Agree?

Ideed I do.
FYI and example: A basically stock CRF 450 peaks some 1200 rpm earlier than that of its factory set rev limit.

My friend and I campaign a CRF 450 in pro dirttrack competition. Using a Vortex ignition and suitable software the rev limit was adjusted to that of 400 rpm (+/- ) over peak power. Said engine with OEM Titanium valves now has some 40 plus hours of hard competition on it and has yet to require a lash adjustment.

Best Regards,
Dale

Valve Tuliping

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