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MountainMax

What are the benefits of doing the yZ Timing?

29 posts in this topic

I was thinking of doing this to my 06 WR450 but wondered if i would lose any bottom end? also do i need to change the exhaust cam? as i heard they are different, finally how many Hp will this get me?

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My memory could be all wrong here, but I think you have to do the YZ exhaust cam along with the YZ timing for 2003s and newer

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The YX timing is not a good mod for the 06. I don't recall why but I remember seeing it here somewhere.

I also think it affects the auto decomp and makes the e-starter unable to turn it over.

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The easy way is to replace the exhaust cam with the YZ cam. The hard way is to press the sprocket off of the stock WR cam and rotate the cam to YZ specs and press it back on. The latter is a job for the experienced tech.

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Just do the YZ cam.....

Much better performance :ride:

It really wakes the bike up. Imagine driving a Diesel truck, and then putting a chip int he truck....thats the effect.

I love it!

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so it's just a simple swap, same timing settings just with YZ cam? will it lose any bottom end grunt? any downfalls doing this?

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from what i understand, gains across the entire powerband.

and the only "drawback" i have heard, is that it is "too snappy" for some riders.

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nice complaint, is this doable on an 06 with auto decompression?

Yes. For the '03 and up, you MUST replace the exhaust cam with the YZ version. Simply retarding the cam one tooth will not work as the auto-decomp pin is longer and opens the exhaust valve too far...SC

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so the YZ has auto decompression also? and should I buy a Yamaha cam or go aftermarket? how many HP/torque gain will this give me? and do you normally re-jet after doing this mod?

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The guy I purchased my bike from already had the cam. (He installed it, but then removed it because it was a bit too much power for him and went back to the WR cam).

Mine is actually the Yamaha cam for the YZ. I have heard others recommend a webber or hot cam for this mod, but they do run more money.

Personally, I don't think it is too much power...... in fact I would like more power still. I would say that it moves the powerband further down the rmp range. Instead of having a slight lag before the power kicks in, its more instant. This works well for sand and track conditions, but I can see where some would dislike it in the slick stuff like mud.

Learn to ride properly and use the clutch though, and its a non issue. In short, it wakes the bike up and keeps it closer to race form, but its not a huge power add on that is going to make the bike scream.

just my $.02

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Can you do this mod to a WR426F 2002 model and do you have to change jets?

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I do not know mutch about the 426. From what I have heard (and someone correct me if I'm wrong); you can change the timing on the 426 to match the YZ 426 timing. The cams are in a lower position (more advanced timing), so retarding the timing 1 tooth allows them to open the exhaust valves at their fullest height (same as on the YZ). :ride:

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What year cam from a YZ450 should I buy from yamaha to work on my 2006 WR450? I am about to order one right now.

I just looked up a 2005 YZ450 cams on yamaha page, but which cam is the exhaust? does the exhaust have three valves or only 2? Im thinking it's the number 2 in this pic but not 100% sure

If i order this cam from yamaha do i use the WR or YZ timing then> want to make sure this will all work for my electric start on my 06 if i do it this way, I need more power.

partimage.gifx?d=61885,2,0

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Its the cam with 2 lobes. You would want the YZ cam and use your current timing.

The only bikes where the timing change was needed were the pre-450 models (once again not positive) [WR400, WR426 - retard them to get the YZ400, and YZ426 exhaust timing] These bikes didn't need a cam swap, just a timing change.

On the 450, you swap out the cam due to the auto de-compression pin. You leave the timing the same and replace the cam since the YZ has taller lobes which open the exhaust valves more.

I stuck with the YZ cam since the guy I bought my bike from already had it, but you might want to look into the hot-cams or webber cam as well. Mine is the actual Yamaha part.

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I thought the 06 yz cam may be differernt, as they come up with updates (like the aluminum frame) usually one year earlier on the yz's before it comes down the line to the wr's.

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05 and 06 YZ cams have the same part #'s

Edit: I've been corrected, they are not the same part #. Too much 2 stroke fumes have blurred my brain and trifocals. :applause:

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