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DeltaT

Updated: CA Sound Test, WR450F Pro Moto Billet Insert Mods and Results

14 posts in this topic

I bought one of Pro Moto's inserts to try modifying it to get the best power... better power than the GYT-R insert, and legal sound. It comes with about 13 holes partially drilled (about 3/4 of the way through) through the billet disk they use as an endcap. I drilled 4 of the holes all the way through, same diameter, after talking to Lyle at PMB. He said it would get louder and a bit punchier as each hole was drilled. There is one hole that houses the retention bolt, so you can't drill it out. It's the one that's only drilled about 1/3 of the way in. You can now feel 4 pronounced mini-exhausts surrounding the main tube, so I know it's flowing something decent.

It passed the sound test today at Hollister, CA, right on the 96DB line (Friend's RM250 was 92DB at the same RPM). Power is better than my GYT-R insert. I rode one loop with each insert to compare. It is noticeably louder but not obnoxious, and legal.

I'm putting in the JD kit Tuesday. I'll post how the 2 inserts compare after the rejetting, too, and have them check the sound again.

Jim

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How did the power feel with the PMB before and after you made the mods? Was there a noticeable difference? I've been using the PMB insert for almost a year now (my WR450 was used for the photo on PMB's website...my claim to fame :D) but my FMF Q will be here next week and I wouldn't mind experimenting with my PMB. :)

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The 4 holes made a modest difference. Before I thought it was just about equal to the GYT-R insert. Now it has a bit more snap, midrange and top end. I'm going to drill out 2 more and probably leave it at that. I need to get used to all this power before I try any other exhaust upgrade, but I will be very interested in your 'Q' results.

Jim

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After informally passing at 96DB at Hollister last week, I drilled out 2 more holes with a 1/4" bit. The others were driller to match the diameter of the decorative holes.

I passed again, with a 97DB, and got my "CA Sound" sticker to put on my red sticker. They said that if you got pulled over and had the sticker (and still had the reasonably quiet exhaust ), they would let you move on.

Later on I went over with the GYT-R Insert with the insert tubes removed. Failed at 99DB - almost 12% above legal.

The Sheriff's Department was out in force, with 8 bikes and a quad. There may have been more but I saw these guys unload and split into pairs. The quad cruised the parking lots and campgrounds alone.

Jim

Beautiful day in Hollister - first time I've been on any of the non-sandy trails.

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Wow, sounds like California has really gone overboard with sound restrictions!

Down here in Florida, loud pipes are common on the road and dirt. We like em LOUD and PROUD! :)

Good luck with your stealth exhaust!

DD :D

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Wow, sounds like California has really gone overboard with sound restrictions!

California gone overboard?!? Double-D, be sure to bring your electronic noise-cancelling system if you ever decide to ride in Michigan. Try 94dB on for size! :D:)

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Wow, sounds like California has really gone overboard with sound restrictions!

California gone overboard?!? Double-D, be sure to bring your electronic noise-cancelling system if you ever decide to ride in Michigan. Try 94dB on for size! :D:)

I have that one beat, here at the Oregon coast dunes it is 93db. :D

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...here at the Oregon coast dunes it is 93db.

93db?? What does everyone use there to meet the sound requirements? :)

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I am sorry but Michigan is nuts to have a 94db level when the USFS has a 96 db level. :) That 2 db is a big difference and really chokes up the WR 450. :D Someone will make a quiet exhaust that flows like an uncorked pipe but my fear is we will all have 55 gallon drum silencers on our dirt bikes. :D

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Phew! Man that's a tough one for sure! I think my joints cracking make more db's than 93! :D

I really don't see why if your riding area is not close to a residential area where the noise would create problems.

I think my uncorked exhaust has actually saved me from nailing wildlife (like deer) where I ride. If I was running 93 db, I would be on them before they knew it.

If it gets any worse than 93, you guys will have to start using batteries and electric motors! :D

If anything I feel your pain. I just hope they don't go noise nuts around here!

DD :)

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And the worst thing is, when they updated the law, they made it retroactive, so bikes that were legal before can fail now. What ever happened to 'ex post facto'? I guess it doesn't apply when they warn you on the way in...

I saw and heard a lot of lot bikes - the 4-strokes are clearly the loudest - but I guess they ticket throughout the day, and I heard the ticket is $133!!! That would ruin my day...

Jim

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I am sorry but Michigan is nuts to have a 94db level when the USFS has a 96 db level.

Reading up on Enduro's on the AMA District 14 web site and they now have a 94db limit.

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...here at the Oregon coast dunes it is 93db.

93db?? What does everyone use there to meet the sound requirements? :)

I bought my wr 400 from jim-in-so-ore here on tt and he made an insert for the stock pipe that got him down to 93 dbs, he rode at the dunes. It is basically the stock insert reworked with a bigger hole and a downturned tip. I can get dimensions and a picture if anyone wants.

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