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YZ timing

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My 05 wr 250f has 1,200 miles on it and i am going to check the valves. I am told this is a convenient time to advance the timing to the yz timing.

What will this do for me.

Is there anything else i could do while i have this apart.

I have most of the free mods done already.

I am sure this timing ? has been asked before, I just wanted to know if there was anything else I could do at the same time.

Thanks

Out Thumped :thumbsup:

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To start with, in order to change to YZF cam timing, the cam is retarded one tooth, NOT advanced.

Secondly, you cannot simply re-time the cam on a WR250F equipped with automatic decompression, because by retarding the cam 22 degrees, you will have the exhaust valve seating too late in the compression stroke to allow the engine to develop enough compression to start.

You can solve this in two different ways. The right way is to purchase a YZ cam and install it using the timing marks on the sprocket as if it were a YZF. The other way is to grind the end of the decompression pin down so that it is 1mm shorter that it now is. This is the Mickey Mouse approach, IMO, and while there are a number of reasonably credible people who will say otherwise, a rat in a dress still has a tail, and I wouldn't do it. If you insist on ignoring that, at least be sure to finish the end of the pin as smoothly as possible, and in as near its current ball shape as you can get.

What you will get from it is a much freer revving engine with about the same bottom end power it now has, and possibly as much as 2 hp.

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Replace your cam chain while your in there, its not expensive and definately worth the money, could save you lots of repairs and a headache later on.

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Has someone here swapped to the YZF cam on the 2005 WR250? (I am NOT talking about 01-04 WR250, just the 2005 or 2006)

From what I have observed with my 05, the top end pull is actually fairly impressive and it behaves a lot more like a YZF cammed bike than I remember of the buddy's 03 WR. I recall the 03 as having fairly good low & mid range, but then falling completely off the bus at upper revs. My 05 is sort of doggy down low, but comes alive in a big way at upper revs.

If I get time sometime, I'll swap some cams and give a report.

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I have swapped the cam in my 05 wr250. The difference was night and day, completely different power characteristics. I hit many trees and dug out of vines for about 4 rides after the mod because there is so much more power and speed carried. The only thing I can think of to describe the difference is the stock wr is a labrador retriever and the yz mod is a pit bull you bitch slapped and tried to out run to the fence. After a little jetting and learning to control the power it is a very worth while upgrade. I highly recommend listening to gray and purchasing a cam, they are inexpensive from the tt store. :thumbsup:

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Brutis, Thanks for the reply. Per my signature, I have a whole garage full of blue bikes right now, so I can do some side by side comparisons. The WR is just plain slow compared to the YZF. I do have a set of Hot Cams on the workbench and I think they will work just fine in the WR.

btw, Have you plugged out your air cut valve? Nice improvement to closed throttle response w/o that thing.

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No I have not done any modification to the acv, I will look into it. Thanks for the tip. :thumbsup:

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I have been reading and reading post's trying to decide what cams if any to change to. I need more low to mid power. If I want the YZF cams what do I need to buy? I have a 05 WR250, do I need the stock cams for an 05 YZ250 and do they have the same auto decompression as the WR cams

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I have searched and read a lot about changing the cams on the WR's most of the post's are for 01-03 WR's.

What do I need to do to change just the exhaust cam on my 05 WR250. Do I need to read a YZF manual to set it to the YZ settings? Do I need to set mine the same as instructed for the 03 and 04 WR's as described in the FAQ section or is the 2005 different?

Thanks for any help

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I have searched and read a lot about changing the cams on the WR's most of the post's are for 01-03 WR's.

What do I need to do to change just the exhaust cam on my 05 WR250. Do I need to read a YZF manual to set it to the YZ settings? Do I need to set mine the same as instructed for the 03 and 04 WR's as described in the FAQ section or is the 2005 different?

Thanks for any help

Get the YZF cam and install it just like it would be installed on a YZF - the 9 o'clock and 12 o'clock dots should line up accordingly, the link below should help ya:

http://www.thumpertalk.com/forum/showthread.php?t=394342

attachment.php?attachmentid=868&stc=1

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