Truth regarding YZ cam timing on old WR

[0macman0]

I can't find anything solid on setting an old 01 WR to Yz cam timing. Which way do you move the exhaust cam from stock timing?

[YZEtc]

You retard the WR exhaust camshaft one tooth (move the exhaust cam one tooth clockwise when standing on the left-hand side of the bike and looking at the cam sprockets).

This gives more valve overlap (both the intake and exhaust valves open at the same time), a much harder hit of power in the midrange and a much harder-pulling top end.

Compared to the stock WR250F, it will then feel like a rocket ship.

But.

It will have less low end torque.

No free lunch, and there has to be a trade-off.

I tried this on my 20002 WR250F, and while I liked the hard-hitting power where I could use it, on the majority of the trails I ride, it was actually not the better type of power delivery, so I put it back to the stock WR cam timing.

If you have the terrain to suit this change, it will be a lot of fun.

Here's something I wrote back in 2013 when I tried this for myself:

 

Edited July 28, 2017 by YZEtc

[Clutch250f]

For this dude, I did the 03 Cam swap on my 01 back in 03 with the YZ205F cam. That was the best way to swap it from WR to YZ timing. I know you can do it with the stock Cam but I'd suggest just swapping the Cam's so you don't have the Four Stroke Drill for starting. I would also suggest getting a Vortex Ignition or a comparable brand and get the two stage mapping. Again I have this so I have what I call my YZ as my main map then I have my WR timing as my secondary. This way I had my YZF cam for the auto decompression and then I could use both timings for when I got myself into a pickle on a Hill.

[DarrellH3]

I have an '07 WR250f. My only complaint is I wish it were a little more snappy for lifting the front tire over logs and the such. I have a rekluse. I'm thinking of trying a yz cam/cams. Can I just use an exhaust or do I need both? I'd rather change the cam if it's necessary to change something on the compression release. What do you guys think? 

[mlatour]

4 hours ago, DarrellH3 said:

I have an '07 WR250f. My only complaint is I wish it were a little more snappy for lifting the front tire over logs and the such. I have a rekluse. I'm thinking of trying a yz cam/cams. Can I just use an exhaust or do I need both? I'd rather change the cam if it's necessary to change something on the compression release. What do you guys think? 

Not sure a cam designed for more mid-to-top power would be the answer, 

rather sounds like you need more low end grunt, perhaps add a few teeth to the rear sprocket.

 

On my very similar CRF250X, for climbing logs and such,

going to a stiffer shock spring and significantly reducing the preload greatly helped in making the front end lift easier.

Edited August 1, 2017 by mlatour

[DarrellH3]

I just know that my sons yz250f has the pop I'm looking for. I like the E-start of the WR and the wide ratio transmission but everything else I like better on the YZ. Maybe the softer seat is the biggest plus.

[0macman0]

I retarded the exhaust cam one tooth as stated, 12 pins between the cam gear marks. Definitely picked up some midrange punch

 

 

[YZEtc]

Great.

So, how do you like it compared to the stock setup?

[0macman0]

Better, I tend to stay in the meat of the power anyways in the mountains. Low end doesn't mean much too me

[DarrellH3]

I just replaced my stock intake cam with an 08 yz cam. It made a bug difference. Downside may be that my rear tire will wear out twice as fast! More snap, which is what I was looking for. Pulls harder. I understand that I have lost low end torque but I run a rekluse so I don't think I'll notice.

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