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12-03-2018, 07:31 PM | #1 |
Join Date: May 2018
Posts: 77
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Db meter + aftermarket exhaust
Is there any one here with a aftermarket ebay exhaust on a hawk that has access to a db meter? AMA dual sport has a 96 db limit on exhaust on rides. Id like to go to shenandoah 500 this year on hawk. Must have spark arrester to does ebay exhaust have that? Thanks for any help i would like to be able to make that trip when i get bike back together.
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12-03-2018, 08:08 PM | #2 |
Join Date: Dec 2017
Posts: 216
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I downloaded a db meter app for my iphone, I compared the readings with a calibrated db meter we have at work......it was dead on.
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12-03-2018, 08:11 PM | #3 |
Join Date: Sep 2017
Location: N Texas
Posts: 706
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I think they would be OK with the ebay exhaust. It does have a spark arrest as long as you bought the same one most of us got. link below. As long as you are not hambone on it it is pretty mellow. 96 dB is pretty loud I would guess from my cursory look on google at dB of different things. But sorry I do not have a dB meter. I wonder if there is an app for that?
https://www.ebay.com/itm/ALUMINUM-EX...-/221555825077 |
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12-04-2018, 08:40 PM | #7 |
Join Date: Sep 2017
Location: N Texas
Posts: 706
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I would download the app and check but I have a short and my battery is dead. No luck kick starting it. I will charge it this weekend.
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12-04-2018, 09:35 PM | #8 |
Join Date: May 2018
Posts: 77
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That be great. Thanks. Im hoping with my increased compression and cam its not to loud i hope lol.
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12-05-2018, 06:12 PM | #9 |
Join Date: Sep 2017
Location: N Texas
Posts: 706
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OK, got er done. I do not know how accurate the app is I recorded startup with a half warm engine at 1/2 choke. I turned the choke off and it went down a lot. Then revved it about 1/3-1/2 throttle a few times. You can see the spikes.
I did the screen shot but then held it at 1/3rd throttle for a few seconds. about 80dB. Looks like you are well within the threshold of 96 dB. I bet you might hit it WOT while in gear. The hawk is fairly low compression. It is not real loud to me. It seems to quiet a bit once warm as well. Hope this helps. |
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12-05-2018, 07:58 PM | #11 |
Join Date: Apr 2017
Location: Omaha, NE
Posts: 8,109
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It would be a good idea to look up what their measuring standards are for dB levels. Usually there is a certain distance and angle from the outlet of the exhaust that they measure from. I.E. 30ft away at a 90 degree angle vs. 10ft away straight on will give two very different dB readings.
I think you are still safe either way. I measured my ebay exhaust with a phone app dB meter and got 92db from about 10ft away straight on at the exhaust outlet, but I can't verify how accurate that was either. As roundhouse said, these bikes are fairly low compression and have pretty conservative ignition timing on top of being a small displacement. You shouldn't have too many issues. I never felt my Hawk was over the top sounding unless it was pegged wide open above 6000rpm under heavy load.
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Hawk Information and Resource guide: http://www.chinariders.net/showthread.php?t=20331 2018 Hawk 250 - Full Mod list here. http://www.chinariders.net/showpost....62&postcount=1 2024 Royal Enfield Shotgun 650 https://chinariders.net/showthread.php?t=34124 |
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12-06-2018, 08:01 PM | #13 |
Join Date: Sep 2017
Location: N Texas
Posts: 706
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Wow, let us know how that project turns out. A few guys have ported and decked their heads giving more flow and higher compression but never heard of an after market cam, let alone adjustable cam gear.
I took my reading with the phone perpendicular to the exhaust maybe a foot behind and 2 feet away from the exit. Yes the spark arrestor is in there. |
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12-06-2018, 11:41 PM | #14 |
Join Date: May 2018
Posts: 77
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Ya i have never heard of anyone on here using a degree wheel on there motors. Cams can be advanced or retarded but not easily. It takes a degree wheel and extra cam gears. Then it takes a milling machine and a 360 indexing fixture and trial and error lol. As far as cam its hard welded with 6 degrees and .016 added. Probally a waste of money but im jack my compression up a good bit welding chamber and reshaping it.
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12-06-2018, 11:59 PM | #15 |
Join Date: Apr 2017
Location: Omaha, NE
Posts: 8,109
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I would leave the chamber as is minus a bit of smoothing of the machinist ridges around the valves, and spend the money on a custom piston. To each his own, obviously, but that would be my approach.
Who did your cam weld/grind? It would be nice to get a mild cam profile change to work with my slightly increased 10.3:1 compression and head porting. The port work really woke up the top end of the rpm range, but I can tell the cam is still holding it back just a little bit.
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Hawk Information and Resource guide: http://www.chinariders.net/showthread.php?t=20331 2018 Hawk 250 - Full Mod list here. http://www.chinariders.net/showpost....62&postcount=1 2024 Royal Enfield Shotgun 650 https://chinariders.net/showthread.php?t=34124 |
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