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03 exhaust cam change into a 02wr250f

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Hi guys.

Is there anyone in Australia that has done the exhaust cam swap on there 01-02 wr250f?

I'm looking at doing this with mine, and am just seeing how many guys from Aus have done it, and how much easier does it make it to start.

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This is just my opinion:

 

I used to have a 2009 WR-250F and that bike had the exhaust cam with the built-in automatic decompressor.

My current bike is my 2002 WR-250F, and like yours, it has the manual deompressor.

 

I feel that if you simply cannot understand or cannot get the hang of how to use the decompressor lever in conjunction with the kickstart lever, the 2003 exhaust cam with auto decomp would probably make sense.

 

In my experience, this is all you are saving yourself from:

Learning the manual decomp drill and having to pull that little lever at the right time every time while bumping the crankshaft just past TDC with the kickstart lever.

 

Other than that, my 2009 model with the auto decomp was no easier or quicker to start when using the kickstarter than my 2002 model with manual decomp is today.

In fact, my 2009 model took, on average, two kicks to start, and my 2002 model takes, on average, one.

Add the extra movement of the 2002 model kickstarter to bump the crank just past TDC, and it's a draw at best in my book.

 

I actually like the manual decomp on my bike.  :)

Edited by YZEtc

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Well my opinion differs^

I purchased a 2001 WR250F and had a hell of a time starting the bike. The bike was properly jetted and I know the "drill". Even though I could get the bike started it required running the "drill" and a very firm kick. I read the YZ cam would improve the power output so more power and easier starting I am on board. It was like the rain stopped and the sun was finally shining, that little cam made the bike a breeze to start. I watched a video where a guy started his bike by hand... I threw on a glove and 2 hand strokes and the bike started! The YZ cam seemed to add a little more power everywhere, didn't notice a loss. If you do search you will find countless posts on people going to the decomp. cam.

Edited by keenxxx

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I am well aware of the consensus on this.

That is my experience with the manual vs. auto decomp.

 

Also, since you mentioned it, when I tried the YZ exhaust cam timing (using the stock WR cam but retarding it by one tooth) on my 2002 WR-250F, there was, indeed, a power loss down low in exchange for much more power from the mid range and up.

On trails that were open and fast enough, this was the hot ticket.

For slow and snotty trails (I'm in the Connecticut woods), it was not the hot ticket because the low end loss was a factor.

Again, that's my own personal experience.

I wouldn't expect to get such a dramatic power gain from mid range and up without a trade-off down low, and I wasn't surprised at all when I found one.

 

My advice for jimswr250f is to do like I did:

If you are curious about any of this stuff, try it and decide for yourself.

If you like the results, great.

If not, you can put it back to how it was.

Edited by YZEtc

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One other benefit of the auto decompression is that you kill your engine while rolling, it is more likely to re - "bump start" rather than skid to a stop. Doing the swap is no problem, and you usually don't need to adjust the valves.

- Toby

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