Db meter + aftermarket exhaust

slowroller · 12-03-2018, 07:31 PM

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.

Hellkitty · 12-03-2018, 08:08 PM

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.

roundhouse · 12-03-2018, 08:11 PM

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

slowroller · 12-03-2018, 09:05 PM

Thanks i guess i messed up posted this in wrong section. I dont have ebay exhaust. Trying to make sure before i buy one its not to loud cause they are strict.

Weldangrind · 12-04-2018, 10:57 AM

I moved it for you.

slowroller · 12-04-2018, 12:34 PM

Thanks for moving.

roundhouse · 12-04-2018, 08:40 PM

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.

slowroller · 12-04-2018, 09:35 PM

That be great. Thanks. Im hoping with my increased compression and cam its not to loud i hope lol.

roundhouse · 12-05-2018, 06:12 PM

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.

slowroller · 12-05-2018, 07:48 PM

Thanks so much. Was that with spark arrester in by chance? Have to have that for forestry and state or fed which ever it is.

Megadan · 12-05-2018, 07:58 PM

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.

slowroller · 12-06-2018, 07:54 AM

Thanks for everones help ill order exhaust as soon as i can. My bike will not be as low a compression as factory. Im working on a adjustable cam gear for my aftermarket cam. So at this point not sure how much pop will come out of exhaust.

roundhouse · 12-06-2018, 08:01 PM

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.

slowroller · 12-06-2018, 11:41 PM

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.

Megadan · 12-06-2018, 11:59 PM

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.

12-03-2018, 07:31 PM	#1
slowroller Join Date: May 2018 Posts: 77	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.
	0

12-04-2018, 10:57 AM	#5
Weldangrind Join Date: Mar 2009 Location: Sardis, BC, Canada Posts: 25,977	I moved it for you. __________________ Weldangrind "I figure I'm well-prepared for coping with a bike that comes from the factory with unresolved issues and that rewards the self-reliant owner." - Buccaneer
	1

12-05-2018, 07:58 PM	#11
Megadan Join Date: Apr 2017 Location: Omaha, NE Posts: 8,044	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. __________________ 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
	2

12-06-2018, 11:59 PM	#15
Megadan Join Date: Apr 2017 Location: Omaha, NE Posts: 8,044	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. __________________ 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
	0

12-03-2018, 08:08 PM	#2
Hellkitty Join Date: Dec 2017 Posts: 216	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.
	0

12-03-2018, 08:11 PM	#3
roundhouse Join Date: Sep 2017 Location: N Texas Posts: 706	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
	0

12-03-2018, 09:05 PM	#4
slowroller Join Date: May 2018 Posts: 77	Thanks i guess i messed up posted this in wrong section. I dont have ebay exhaust. Trying to make sure before i buy one its not to loud cause they are strict.
	0

12-04-2018, 12:34 PM	#6
slowroller Join Date: May 2018 Posts: 77	Thanks for moving.
	1

12-04-2018, 08:40 PM	#7
roundhouse Join Date: Sep 2017 Location: N Texas Posts: 706	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.
	0

12-04-2018, 09:35 PM	#8
slowroller Join Date: May 2018 Posts: 77	That be great. Thanks. Im hoping with my increased compression and cam its not to loud i hope lol.
	0

12-05-2018, 07:48 PM	#10
slowroller Join Date: May 2018 Posts: 77	Thanks so much. Was that with spark arrester in by chance? Have to have that for forestry and state or fed which ever it is.
	1

12-06-2018, 07:54 AM	#12
slowroller Join Date: May 2018 Posts: 77	Thanks for everones help ill order exhaust as soon as i can. My bike will not be as low a compression as factory. Im working on a adjustable cam gear for my aftermarket cam. So at this point not sure how much pop will come out of exhaust.
	1

12-06-2018, 08:01 PM	#13
roundhouse Join Date: Sep 2017 Location: N Texas Posts: 706	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.
	0

12-06-2018, 11:41 PM	#14
slowroller Join Date: May 2018 Posts: 77	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.
	0