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crash279

2 09 WR450's 2 Different Performance Characteristics?!?!

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Like the title says, I have two 09 WR450's. One is my supermoto the other is a dual sport. The supermoto has very little bottom end but has a decent mid-range to upper end pull. Compared to my '06 it has no bottom end. I just finished building my dual sport and it feels more like what I would expect from a 450. In fact it feels like it would flat out run away from my supermoto on one wheel. I want my supermoto to match my dual sport's power. They're similarly modded, but different year parts. Here's the rundown:

2009 WR450 Supermoto:

Hotcams YZ450 exhaust cam

'08 YZ450 exhaust header

FMF slip on

GYTR jetting kit #50 pilot/#170 main

2009 WR450 Dual Sport:

2007 YZ450 exhaust cam

'06 YZ450 exhaust system (header and exhaust)

JD jetting kit #50 pilot/#170 main/blue needle

Does anybody have any ideas on what I should change? I know that the headers are different, but does the '08 throw off the performance that much? Should I get a '06 exhaust cam? Does the blue needle make that big of a difference?

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I bought my '06 used and the previous owner told me not to waste my time fiddling with the jetting, "I've got the jetting dialed!", was his words. After a couple of months of riding, I still wasn't all that impressed, so I dove in there to see what jetting he had. It was the GYTR kit, and since I already had a JD kit laying around, I threw in the JD kit. Much better!! How about your gearing? Are they the same for both?

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The gearing is certainly a variable to consider and if the supermoto is on 17 inch wheels, even more so. Otherwise the cam may be the most significant factor but difficult to compare without knowing the timing details for each one.

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I bought my '06 used and the previous owner told me not to waste my time fiddling with the jetting, "I've got the jetting dialed!", was his words. After a couple of months of riding, I still wasn't all that impressed, so I dove in there to see what jetting he had. It was the GYTR kit, and since I already had a JD kit laying around, I threw in the JD kit. Much better!! How about your gearing? Are they the same for both?

The supermoto is 14/40 and the Dual Sport is 14/42. I know two teeth won't make this big of a difference lol. I mean, I wish it would.

The gearing is certainly a variable to consider and if the supermoto is on 17 inch wheels, even more so. Otherwise the cam may be the most significant factor but difficult to compare without knowing the timing details for each one.

They are both YZ timing. The supermoto has the YZ450 hotcam and the dual sport has a '07 YZ450 exhaust cam.

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I'm sure the timing marks are the same, but is the opening point before TDC, lift, and dwell (period of opening) the same on both exhaust cams?

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I'm sure the timing marks are the same, but is the opening point before TDC, lift, and dwell (period of opening) the same on both exhaust cams?

From what I understand the hot cam is nearly identical to the '06 YZ450 cam. The '07 is similar to the '06 as well. '08 was when they re-did the cam duration.

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Well if the cam is pretty much identical that rules that out. How about swapping the different bits over and finding out how much difference it makes. The jetting sounds the same except for the needle or is the needle jet/atomiser also different on the JD kit. Presumably the throttle valves have the same cutaway.

At least with two otherwise identical bikes it's possible to do substitition tests.

I change gearing a fair amount on my 450F as it's only a 4 speed to suit the different speed hill climb courses. If both bikes run 18 inch rear wheels 2 teeth isn't going to be that significant, but 2 teeth less and a 17 inch wheel is going to be more like going up one on the gearbox sprocket with the same rear. I can certainly tell the difference when I do that by the ease of pulling power wheelies. Mind you, my tuned 450 will still aviate the front nicely off the line on 15/40 gearing.

To be really sure they are that much different back to back dyno runs would be interesting.

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2009 WR450 Supermoto:

'08 YZ450 exhaust header

2009 WR450 Dual Sport:

'06 YZ450 exhaust system (header and exhaust)

Does anybody have any ideas on what I should change? I know that the headers are different, but does the '08 throw off the performance that much?

I have an 08 WR and when I built my bike, I originally installed an 08 YZ header. Probably a year later, I decided to try a 06 YZ Header. The results work extremely noticeable. 06 Header was a torque monster but had not top end. The YZ header was all mid to top end with a nice over rev. Trying both headers, I was using the stock cams with a FMF 4.1 exhaust.

Hope this helps.

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try swapping exhausts.. takes 10min. header dia makes a big diff like Coopdog says

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Well if the cam is pretty much identical that rules that out. How about swapping the different bits over and finding out how much difference it makes. The jetting sounds the same except for the needle or is the needle jet/atomiser also different on the JD kit. Presumably the throttle valves have the same cutaway.

At least with two otherwise identical bikes it's possible to do substitition tests.

I change gearing a fair amount on my 450F as it's only a 4 speed to suit the different speed hill climb courses. If both bikes run 18 inch rear wheels 2 teeth isn't going to be that significant, but 2 teeth less and a 17 inch wheel is going to be more like going up one on the gearbox sprocket with the same rear. I can certainly tell the difference when I do that by the ease of pulling power wheelies. Mind you, my tuned 450 will still aviate the front nicely off the line on 15/40 gearing.

To be really sure they are that much different back to back dyno runs would be interesting.

I think that it's a combination between the JD needle and the exhaust header. I swapped an '07 header and it helped the low end a little bit, but I think I'm gonna just leave it as is.

I have an 08 WR and when I built my bike, I originally installed an 08 YZ header. Probably a year later, I decided to try a 06 YZ Header. The results work extremely noticeable. 06 Header was a torque monster but had not top end. The YZ header was all mid to top end with a nice over rev. Trying both headers, I was using the stock cams with a FMF 4.1 exhaust.

Hope this helps.

Actually that was very helpful, thank you!

try swapping exhausts.. takes 10min. header dia makes a big diff like Coopdog says

Did that and it made a little different. I'm just gonna leave well enough alone for now.

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Did that and it made a little different. I'm just gonna leave well enough alone for now.

When you say you swapped exhaust , did you just swap mufflers? Try the headers...I'd be willing to bet that makes all the difference in the world

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When you say you swapped exhaust , did you just swap mufflers? Try the headers...I'd be willing to bet that makes all the difference in the world

That's what I swapped. I put one off of a '07 and it perked up the low end a little. I decided that I like the power coming on more in the mid to upper range on the supermoto a little better.

Edited by crash279

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