vavletrain

[bama400ex]

i want opinions on if yall would think this would work or not. ok we all know getting the rockerarms hardend cost $$$. so i was trying to think of a way around this. ok so the arms wears faster from the bigger cam because of the stress from the valve springs being compressed down farther. correct? so i was wondering why someone couldnt take the head and machine it down some where the valve spring sets. then if you could find some longer valve springs you'd be set. that way you could get the spring rate close to stock. if you had the right size spring that is. so what do you people think. the arms may still wear at a faster rate because of the fastrer lobes on the cam perhaps but i bet this would help a great deal. if only you could find the right size spring. anyone?

[bama400ex]

btt

[bama400ex]

anybody?

[Teufel]

Buy the rockers!!

[bama400ex]

i will probally, this was just a thought.

[Dunlap]

The problem is not with the heavy duty valve springs. Heat is the main problem with the 400EX. That's why we offer the secondary oil cooler that pumps the cooler oil directly into the head. We have been running this system on Chad Duvall's 500EX. We inspected it after 40 hours of race time with the stock rocker arms and everything was perfect. While I am not ready to say that you don't have to harden your rockers, it appears that the 2nd oil cooler is taking care of the problem. However, these were new rocker arms on a new engine. Most of the problem occurs when someone puts a new cam in with old rocker arms that have already started to wear through the chroming. If you went lighter springs like the stockers when you are putting in a cam, it is possible to break valves from the lack of seat pressure. When the valves hit the seat, they bounce causing harmonics and breaking the valve from the inside out. I hope this answers your questions. Thanks for inviting me onto the forum.

[bama400ex]

i knew you could shed some light onto this. like i said it was just a thought and figured if it would work somebody would already be doing it. i was just wondering why nobody was. thanks for taking the time to answer! your help is greatly appreciated!

[deansfastway]

I agree with DUNLAP The primary attribute to the rockers wearing is heat and breakdown of the oil . His engines are at the EXTREME tune thats why he needs a twin cooler system. At my shop we send the rockers out for CRYOTHERM treatment (cold tempering process) its cheap and seems to work . There is not much room on the EX casting to be machining down spring seats . We custom machined a 400 head with a more inclined valve angle which required oversize guides and refitted seats. We had to use lash caps on the tips of the valves . This was in an attempt to get more flow on a bench . We and lots of other DRAG RACE shops do this to bikes (really helps the HYABUSA) . The best headwork we ever did (to EX) was welding up and You need more seat pressureraising the actual exhaust port @10mms and welding up the floor of the exh port to make it D-shaped . You need more seat pressure at zero lift of the valve to help the rockers / valve follow the cam and keep the assy from floating on high Rs if they float the keepers fall out and there goes your motor/investment.The ideal setup would be a desmodramic system like DUCATI has it uses no valve springsonly opposing followers on each side of the camshaft . Valve springs actually cost horsepower lost in drag , it saps energy to compress those valve springs.. Auto & truck manufacturers are developing pneumatic systems to open & close valves. The future looks interesting as these systems come to powersports. FASTWAY MOTOSPORTS . P.S. Those aluminum spoilers can really help cool down your motor fot cheap$$$.

[Teufel]

I would agree that the heat is a factor, but I disagree when you say that the heavier springs aren't the problem. We just went through this with a 300ex. The kid had added the cam and springs without replacing the rockers with the hardened ones. It came apart within 20 hrs ride time. When I go the motor I still had to convince him to use the hardened rockers. To do that we compared the stock with the aftermarket springs. The aftermarket springs have more than 2.5 time the tension than the stockers. The stock rockers were designed to run with the stock spring tension and they work fine in that enviornment. Increase the pressure 2.5 X and they deterioate faster. Would additional lubrication help? Probably but it is a bandaid for the problem. When up grading, it is essential to use components that are engineered to work together.