08WR450 LeoVince X3 or FMF Q4

[Demo_Slug]

Sweet.

The first ride with the new pipe last week I couldn't feel the extra power because the rear tire would light up if I even looked at the throttle (extra loose conditions). Judging by the way this thing acts on asphalt I'm gonna be in a world of hurt when conditions are good and traction is abundant ?

I'm with you... I'm keeping my old exhaust around for when things get "impassible when wet" .

but I could feel the power increase. because I was getting small unexpected roll on wheelies in what I thought was too loose for traction, just dig a bit deeper to find the hard pack. and it sounded like more pow pow:devil:

but I'm really pleased that the whole thing worked out. its not like the exhuast manufactures provied any answers in regards to fitting up a yz head pipe.

[JSanfilippo]

Ok to say that I couldn't feel the power was inaccurate. On the steeper longer hills at carnegie it could run a gear high, roll completely out of the throttle, and then roll back on without hearing the "clacking" sound or downshifting into the correct gear. Don't get me wrong with the stock pipe/PMB insert it would pull taller gears up hills, but if I got out of it I'd either need to downshift or hit the clutch a little get it into the midrange.

Also I could pull a gear higher on the turns on the MX and ATV tracks without any stumbles. On the trails though any increase in throttle resulted in violent tire spin.

[Demo_Slug]

Ok to say that I couldn't feel the power was inaccurate. .

busted. ? yeah, turning power into speed is kind of an issue.

[coloradobrad]

Thanks for the info via PMs. I ordered the LV X3 WR gasket from Italy. It'll be here 10/15

For the short term I swedged a piece of 1.5" stainless pipe inside of a 1.75" piece and made a collar that's ~45mm OD and ~39mm ID. I got swedge happy so it's about 1mm loose - red RTV fixed that

The pipe is full of win! Way nicer than the FMF Q-pipe on my 03 and the power is way better than my ghetto gutted stocker.

Regarding headers, it would seem the 38mm WR header would offer better low end power since the exhaust gas velocities are higher than in a yz header. Higher gas velocity -> more vac on the cylinder -> better low rpm scavenging. Maybe like the powerbomb SX header... It's a skinnier pipe than the other FMF headers. I need to study on this.

[fleshwoundracing]

i used to manage a shop and most customers went with the q4 cuz its affordable and an amazing pipe.i would go with that imo

[Demo_Slug]

coloradobrad,

To bad about the October delivery on the gasket. But seems like you figured it out.

What muting baffle are you using? you got the YZ X3 so it probably has the 35mm outlet muting baffle or are you running without? I was running without when I had the 38mm header. It was still quieter then the MX bikes on the trail… very basy.

It ran really good with the 38mm header pipe, with or without muting tip, but I didn’t really like the sound of the 25mm tip. it sounded turbulent.

Hard to really say what sort of improvement the YZ header made, because I installed the 35mm tip(got it on ebay) at the same time.. I don’t think it changed the low end, but it did pick the front end up a bit more often in the mid RPM range.

I’ve been thinking about going back to the 38mm pipe. The YZ header is a lot bigger and hangs out more, it makes my leg hot and I’m getting worried about crushing it on the rocks.

In regards to back pressure in the pipe. ???? some guys talk velocity, some guys talk wave propagation. I’m in the don’t know camp. If your talking wave propagation, then the longer pipe gives you better low end. (more volume can appear longer).

[Demo_Slug]

and something to read about backpreasure

http://www.flowmastermufflers.com/backpressure.html

[coloradobrad]

and something to read about backpreasure

http://www.flowmastermufflers.com/backpressure.html

Thanks for the link. Sometimes I wish I engineered engines instead of electronics

That's good to know about the YZ header. Let me know if you decided to sell it. I may give it a try. As for the powerbomb SX header, I don't see one for the 07-08 WR or newer YZ on the FMF website. Maybe it was discontinued.

I'm not sure which tip I'm running. I think it's the 35mm. I have 3 of them and an s/a. 2 of them are the same diameter (35mm), but one is short so it fits with the spark arrestor. The other looks like maybe its 30-32mm. I suppose I should order the 25mm insert to be legal in the woods. New laws on 7/09 impose a 96dB limit.

[Demo_Slug]

Thanks for the link. Sometimes I wish I engineered engines instead of electronics

That's good to know about the YZ header. Let me know if you decided to sell it. I may give it a try. As for the powerbomb SX header, I don't see one for the 07-08 WR or newer YZ on the FMF website. Maybe it was discontinued.

I'm not sure which tip I'm running. I think it's the 35mm. I have 3 of them and an s/a. 2 of them are the same diameter (35mm), but one is short so it fits with the spark arrestor. The other looks like maybe its 30-32mm. I suppose I should order the 25mm insert to be legal in the woods. New laws on 7/09 impose a 96dB limit.

with the 38mm header you shouldn't have any issues with 96dBs..... if you look at www.leovince.com they have sound measurmenst for each pipe. the WR450 with 38mm header and 25 mm baffle was 94db at 6200RPM. should be even quiter at 4500RPM. the 07YZ hits 96db at 4.5K with the 35mm tip. and keep in mind the sound measurments are A weighted, so it doesn't mater so much that the pipe has more low frequency.