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tksmith

07 YZ450F Cam Trick?

12 posts in this topic

I have been told by a friend that works on bikes that if you take and retard the exhaust cam one tooth on the YFZ450 it is the same as putting in a hot cam. It gives like a 20% power increase. Does anyone know if the is true? I would like to do it to my YZ450F but I am not sure if the engines are set up the same. Any light on this would be great.

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well dont try it until you get a go from a mechanic or your going to put a valve though your head

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ya that is why i haven't done it yet. My friend that told me that is a service tech. and they were doing it to a brand new 450 while is was standing there.

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Changing the cam timing is something that has been done on the YFZ QUAD, not the YZF BIKE. The quad comes with WR spec timing. Don't mess with the cam timing in your bike.

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i raced a yfz450 last year( only year on quads, back to two wheels!) and yes that was a mod for the quad, but do NOT do it to a yz450f, the reason that was done was to make the cam timing the same as a bike wich was for more top end, your bike is already timed that way

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The YFZ (quad) comes with the timing advanced to make it less powerful (same as the WR450). By retarding the timing one tooth you make it have the same timing as the YZF (bike) is stock. If you retard the timing on a YZF it will run like crap. Hotcams will add more power than a YZF is stock.

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The advanced cam timing in the quads and WR's increases the low end torque and smoothness of the engine, too.

But since these are all auto decompression cams, there's another problem: when you change the cam timing, you also change the timing of the point at which the decompression pin will let the exhaust valve reseat. When you retard the cam in a quad or WR, you will quite often end up with so little cranking compression that the engine will not start. Yamaha deals with this by using shorter pins in these engines. Some modifiers will get around the problem by grinding a certain amount off the pin, but I cannot recommend doing this, since the finish put on the end of the pin may not be very good, and wear at the lifter could result.

Likewise, advancing the cam will cause the pin to seat the valve too soon, and it will be unreasonably hard to start.

The right way to do this is to use the cam from a YZ (year of your choice) in the quad or WR you're modifying.

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Gray, Do you know what the camshaft profile is for the WR? Just wondering if it would be and option for the low-end issues everyone is complaining about with the '08's.

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Gray, Do you know what the camshaft profile is for the WR? Just wondering if it would be and option for the low-end issues everyone is complaining about with the '08's.

There is NO problem with the 08 once you ditch the stock silencer. Alot of people however like the mellow low end hit the stock pipe gives.

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Gray, Do you know what the camshaft profile is for the WR? Just wondering if it would be and option for the low-end issues everyone is complaining about with the '08's.

Not a good idea unless you just want to loose some power. The answer for the '08 is an exhaust system.

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