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BrianVT

How loud is my exhaust ?

6 posts in this topic

I yanked the Big Gun that came with my bike and put a drilled stocker on. It seems alot quieter and I don't think I gave up much, if any, power. Though it adds some weight.

Well, I got sound checked last year with the Big Gun at 95db. Yesterday the stocker tested 104db ! I couldn't believe it. Maybe I revved too high ?

Assuming equal r.p.m.s, could the stocker be louder ?

I'm thinking I'll put the lighter Big Gun back on.

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That's weird Brian...I have the HRC tip. Wonder how loud it is. any west coasters been tested?

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There are several factors that can affect the sound level. I've never been personally tested, but I've talked with a few XR650R riders who have and their bikes with the stock exhaust & HRC tips have tested from about 95 to 97dba. One person I talekd to said he was tested at just under 97 dba and later that day he was tested at the same exact riding location by a different ranger at just above 99 dba :thumbsup:.

In any case, check out the following pdf link for some examples of test data gathered on Honda 's. The XR650R info is near the end of this document, but you can also just use the search function for XR650R.

http://ohv.parks.ca.gov/pages/1140/files/honda.pdf

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Thanks for the link Qadsan. The tester just said rev it and didn't have a tach with him. I was probably close to 7k. That chart clearly shows the Big Gun is louder. Next time I'll ask how many revs before I give it to him.

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The actual test RPM the Morotcycle Industry Council uses for the XR650R when measuring sound output is 3,250 RPM. Bikes in general are tested at the engine RPM where half their peak power is made, but there is an official book which has all the bikes and their test RPM's listed.

http://www.mic.org/content/nonmembers/memberdirectory/downloads/2001_2003FormFinal.pdf

Here's some details of how testing is supposed to be done, but make note that official testing by a ranger that's enforcable 'must' be done with a 'type 1' sound meter (that's calibrated), otherwise the testing is void from enforcement from what I understand.

Location Of The Microphone Of The Sound Level Meter. (7-1-94)

a. The microphone of the sound level meter shall be located twenty (20) inches - one-half (1/2) inch behind the exhaust. If there is more than one (1) exhaust outlet per side, the microphone of the sound level meter shall be located with reference to the rear most outlet. (7-1-94)

b. The microphone of the sound level meter shall be within one-half (1/2) inch of the height of the exhaust outlet. (7-1-94)

c. The microphone of the sound level meter shall be at a forty-five (45) degree - ten (10) degree angle to the normal line of travel of the OHV. (7-1-94)

d. The longitudinal axis of the microphone of the sound level meter shall be in a plane parallel to the ground plane. (7-1-94)

e. The axis of the microphone of the sound level meter shall be oriented as specified for field response by the manufacturer. (7-1-94)

04. Attachments Prohibited. No wire or other rigid means of distance measurement shall be attached to the sound level meter measuring system.

TEST PROCEDURE.

01. Test Site. The test site must be a flat, open surface free of large reflecting surfaces, other than the ground, such as parked vehicles, signboards, or hillsides located within sixteen (16) feet of the (OHV) being tested and the location of the microphone of the sound level meter. (7-1-94)

a. Ambient sound level. The ambient sound level, including wind effects, at the test site due to sources other than the OHV being measured shall be at least ten (10) dB lower than the sound produced by the OHV under test. (7-1-94)

b. Wind speed. Wind speed at the test site shall be less than twenty (20) miles per hour. (7-1-94)

c. Persons in test area. While making sound level measurements, not more than one (1) person other than the operator, the measurer, and the assistant, if necessary, shall be within ten (10) feet of the OHV under test or the microphone of the sound level meter, and that person shall be directly behind the measurer on a line through the microphone of the sound level meter and the measurer. (7-1-94)

02. Test Surface. The surface of the ground within the test area shall be paving or hard packed earth, level within an average slope of five (5) inches per foot and shall be free of loose or powdered snow, plowed soil, grass of a height greater than six (6) inches, trees, or other extraneous materials. (7-1-94)

03. Position Of OHV. (7-1-94)

a. For two (2) wheeled OHVs, the operator may sit astride of the OHV, in normal riding position with both feet on the ground. If this is not possible because of the seat height of the OHV, an assistant may hold the OHV by the forks, front wheel , or handlebars so that it is stationary with its longitudinal plane of symmetry vertical. If an assistant is not available to assist in holding the OHV upright, the operator may use a box, rock or other object to rest his feet upon to steady the OHV, so long as the OHV longitudinal plane of symmetry is vertical and stationary.(7-1-94)

b. For three (3) wheeled and four (4) wheeled ATVs, the operator may sit in the normal riding position with one (1) or both feet on the footrests. (7-1-94)

04. Operation Of OHV. (7-1-94)

a. If the OHV has a neutral gear, the operator shall run the engine with the gear box in neutral at a speed equal to one-half (1/2) of the rated engine speed or one-half (1/2) of the red line speed specified by the manufacturer as compiled in the Off Highway Motorcycle and ATV Stationary Sound Test Manual. (7-1-94)

b. If the OHV has no neutral gear, it shall be operated either with the rear wheel(s) at least two (2) inches clear of the ground or with the drive chain or belt removed, or the clutch, if the OHV is so equipped, disengaged. (7-1-94)

05. Engine Temperature. The engine of the OHV being tested shall be at a normal operating temperature.

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I was at the same event as Brian, the Mowhawk Turkey Run, and I got 102db with the HRC tip. I tried not to rev it too high. The guy even had to prompt me to rev it higher. When I did, he starded shaking his head. I am glad to find out your drilled stocker did poorly also, as I was going to put that back in instead of the HRC tip to reduce noise. The guy doing the sound tests said everyone with a downturned tip did fine. I guess I will be looking to make one. The sound test seemed to be operated according to guidelines listed by Qadsan.

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