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VVT and Removing YZ450f Cam Sprockets

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Hey guys, 

Currently working on a VVT project, but my cams are 300 miles away for a couple weeks while I get settled at my new place. 

Are the sprockets pressed onto the camshaft and then keyed in place? I'm trying to figure out if I can press the cam sprockets on/off and replace them with some phasors. 

Thanks, 

Cal

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Ahh, interesting. It must be a pretty significant press fit if they trust the press to take all of the load. Thanks for the info!

For those interested, I'm building a mechanical phaser for the intake. It should be a direct fit (with clocking press fixture) for stock stuff... at least that's what I'm trying for. 

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They are a keyless press fit, and it is significant.  It is inadvisable, though to press them off and then back on in another position without tacking them in place for security.

The other matter that needs to be addressed is that the auto-decompression mechanism includes a flyweight that mounts on the sprocket, and the pin that lifts the exhaust valve off it's seat is located in the camshaft itself.  The pin position relative to the lobe cannot be changed as the cam is currently configured, and changes in cam timing directly affect the timing of the point at which the exhaust valve is seated to start the cranking compression stroke.  In a stock YZ450, the valve seats roughly 20 degrees BTDC with the decomp active.  It doesn't take very much retard to render the compression too low to start, nor much advance to make the electric start unusable, if you have one.  The cure for the first condition is often to grind the pin shorter. 

Alternatively, it may be possible to enlarge the hole in the cam from which the pin protrudes to accept a bushing, which could then be made in various offsets to alter the decomp timing to suit changes in cam timing.

Sidebar: Yamaha was the builder for the SHO 6 cylinder Ford Taurus engine.  The engines were shipped as components to be assembled by Ford, which is not something Yamaha will likely do again.  Ford made some changes to the methodology involved with pressing the cam sprockets in place on the engine in order to save some time and money in the process, and ended up causing a sort of rash of failure due to slipped sprockets.  Some corners can't be cut.

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