I JUST PUT A NEW PISTON (10.25 1) A NEW WEB CAM ( 290 ) NEW TITANIUM VALVE SPRINGS AND ADVANCED THE TIMING 5 DEGREES. PUT IT ALL BACK TOGETHER (WITH NEW GASKETS) ADJUSTED THE VALVES, PUT THE HEAD ON WITH THE CORRECT TORQUE AND IT RAN GREAT. CRANKED ON THE FIRST TRY. I BROKE IT IN AND THEN RODE IT HARD FOR 2 DAYS. THE NEXT TIME I RODE IT IT CRANKED FINE RAN FINE AND THEN "WHAM" A BIG NOISE IN THE MOTOR. WHEN I PULLED THE HEAD OFF THE INTAKE VALVE WAS BROKEN OFF AND THERE WAS JUST A NUB LEFT. THE PISTON WAS MANGALED AND THE HEAD WAS TOAST. THE INTAKE VALVE SPRING WAS APPART WITH THE ROD OF THE VALVE BENT BUT STILL IN THE VALVE SLEEVE. DOES ANYBODY HAVE AN IDEA WHAT MIGHT HAVE HAPPENED? IF THE TIMMING WAS OFF WHY COULD IT HAVE RAN LIKE A "BAT OUT OF HELL" FOR 2 DAYS AND THEN HIT THE INTAKE VALVE? IF IT WAS NOT THE TIMING COULD IT HAVE BEEN A WEAK VALVE? ANY THOUGHTS PLEASE RESPOND.

 

wow, i don't no what to say. i really have no idea bro. that just sounds totally off.
maybe it was the Blair Witch...

 

Pure conjecture follows:

In my misspent youth, drag-racing motorcycles, the symptoms you describe were called, "sucked a valve," as in, "Nasty Ed's Harley sucked a valve."

One possible scenario; if the valve spring keepers let go, the valve falls into the combustion chamber, the rising piston breaks off the valve head and bends the stem, while the loose valve head bounces around inside the cylinder making a loud, expensive noise.

The higher lift and steeper profile ramp of your WebCam, compared with the stock camshaft, along with the stronger valve springs you installed, all create added stress on the valve spring keepers and their . . . wait! I'm making "smart talk" again! The Arctic Cat riders are getting headaches already. Sorry, guys; I'll stop!

Tree Farmer

[This message has been edited by Tree Farmer (edited 08-17-1999).]

 

sounds like a valve keeper broke= murphy's law=$$$$$$ ouch!!!!!!

 

THE CAM YOU USE IS I'M GESSING A 390 LIFT WITH IS NOT REALY ANY MORE RADICAL THAN STOCK. IT SOUNDS LIKE A RETAINER JUST BROKE. IF YOU USE THE 430 CAM AND REV IT HARD IT WILL SUCK A VAVE QUICK. I AM USING THE 390 CAM AN HAD NO PROBLEMS AND I RACE MY WARRIOR HARD AND AM NOT EASY ON IT.

 

Classic "Dropped" valve been there Broke that.

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Kevin Gowdy AKA-Kagey1999 Polaris Magnum 500