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carnett2
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« on: July 16, 2015, 08:22:24 PM » |
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Do I need to rejet to change over to Cobra 6 into 6 exhaust?
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R J
Member
Posts: 13380
DS-0009 ...... # 173
Des Moines, IA
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« Reply #1 on: July 17, 2015, 12:03:02 AM » |
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I never rejetted MGM when I had those noisy SOB's on. This is just my opinion from a lot of highway miles.
I did rejet when I went with the Viking pipes just to get all of the assistance from those pipes to get MGM to run like a scolded dog.
I love the Vikings. They have a mild tone and will bark when ya get on it hard.
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44 Harley ServiCar   |
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98valk
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« Reply #2 on: July 17, 2015, 02:50:21 AM » |
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Do I need to rejet to change over to Cobra 6 into 6 exhaust?
been posted many times, search is your friend. don't be afraid. their jetting kit was basically adjustable needles and lighter springs, main jets and pilot jets were never part of the kit. it was always wrong that they called it a jet kit. unless u modify the airbox by letting much more air in no need to change actual jets. u can do the same, add washers to your oem needles to raise them up and use the I/S oem slide springs which are weaker than the std/tourer springs. always run the front two carbs needles slightly richer with a thicker washer than the rest. |
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1998 Std/Tourer, 2007 DR200SE, 1981 CB900C 10speed
1973 Duster 340 4-speed rare A/C, 2001 F250 4x4 7.3L, 6sp
"Our Constitution was made only for a Moral and Religious people. It is wholly inadequate to the goverment of any other."
John Adams 10/11/1798
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Attic Rat
Member
Posts: 446
VRCC # 1962
Tulsa, OK
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« Reply #3 on: July 17, 2015, 06:32:20 AM » |
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NO
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The Attic Rat Performance Works
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Bighead
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« Reply #4 on: July 17, 2015, 06:40:52 AM » |
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1997 Bumble Bee
1999 Interstate (sold)
2016 Wing
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Whitster
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« Reply #5 on: July 17, 2015, 09:17:13 AM » |
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I put Cobra 6 into 6 pipes on my 99 Valk Interstate, earlier this year. I did a lot of reading/research before deciding on the jetting changes I made. Here's what I ended up doing: #38 pilot jets (genuine Keihin), along with #108 main jets (also genuine Keihin). I left the stock Honda needles in their stock position (no extra washers, or other modifications). I put the mixture screws at 2.25 turns out from fully seated. One more thing: I left the Cobra baffle/silencer assemblies installed in my pipes. It's plenty loud enough (without being "Stupid Loud"). My bike runs & sounds Great!! No backfiring or misbehaving during deceleration, or at any other time. I've put around two thousand miles on these pipes, with No Discoloration Whatsoever!! I Love the sound, especially when I crack it open, & run the RPMs up a bit. Sounds sort of like a finely tuned Ferrari, or perhaps a DOHC Inline 6 Jaguar (with louder exhaust). If you like your bike quiet, then these pipes are not for you. However, if (like me) you like to hear a more sporty, throaty, exhaust note........Then You'll LOVE THEM!! Everybody has different opinions on this subject. It's all a matter of personal taste. Do what You Like Best!!
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98valk
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« Reply #6 on: July 17, 2015, 03:51:31 PM » |
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http://www.valkyrieforum.com/bbs/index.php/topic,1262.40.htmlThis was posted by J. Orr, 3/27/1998, on the GWRRA BBS, valkyrie section. The following mods were done by Marc the owner of Factory Pro of a valkyrie that had cobra 6x6 pipes. K&N filter (w/o prefilter) Air box mod (remove plastic welded baffle) 38 pilot jet 3.5 turns idle mixture screw front needles set on #3 mid and rear needles set on #2 115 main jets all carbs this picked up 5 hp over the base run with the cobras which are down about 10 hp from stock. this HP is still down from the stock pipes I talked to Marc when I was jetting my bike w/glass pac mod about the cobras and the testing on the above bike he did, he said, "u can only get back to stock oem HP, anymore and major jetting and air inlet changes need to be done but mpg will go down." more or less his words.
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1998 Std/Tourer, 2007 DR200SE, 1981 CB900C 10speed
1973 Duster 340 4-speed rare A/C, 2001 F250 4x4 7.3L, 6sp
"Our Constitution was made only for a Moral and Religious people. It is wholly inadequate to the goverment of any other."
John Adams 10/11/1798
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salty1
Member
Posts: 2359
"Flyka"
Spokane, WA or Tucson, AZ
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« Reply #7 on: July 17, 2015, 07:29:18 PM » |
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NO
 Mine ran just fine without rejetting. |
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My rides: 1998 GL1500C, 2000 GL 1500CF,2006 GL 1800 3A   |
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carnett2
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« Reply #8 on: July 18, 2015, 07:14:56 PM » |
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Thanks all for the advice
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Guitarmoto
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« Reply #9 on: June 20, 2021, 12:37:56 PM » |
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I'm glad I searched this. I just got some cobra 6 in to 6 pipes and had the same question. The guy is helping me install them says no worries I'm rejecting but can decide later if I feel it needs it. I'm wanting to put the pipes on and put a can and filter in at same time, think this will cause any issues?
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98valk
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« Reply #10 on: June 20, 2021, 02:02:14 PM » |
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I'm glad I searched this. I just got some cobra 6 in to 6 pipes and had the same question. The guy is helping me install them says no worries I'm rejecting but can decide later if I feel it needs it. I'm wanting to put the pipes on and put a can and filter in at same time, think this will cause any issues?
K&N lets in a ton of dirt. see testing http://www.billswebspace.com/AirFilterTest.htmstick with the OEM filter keeps dirt out and flows lots of air. I dyno'd 116 HP with oem, no problems |
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1998 Std/Tourer, 2007 DR200SE, 1981 CB900C 10speed
1973 Duster 340 4-speed rare A/C, 2001 F250 4x4 7.3L, 6sp
"Our Constitution was made only for a Moral and Religious people. It is wholly inadequate to the goverment of any other."
John Adams 10/11/1798
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DeathWishBikerDude
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« Reply #11 on: June 22, 2021, 07:21:40 PM » |
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All my bikes that had cobra pipes ran like  I punch out the baffles on the stock exhaust and the bike runs so much better. Got 2 pairs of junk cobra rusting in my basement  |
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PSUbag
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« Reply #12 on: June 23, 2021, 10:44:41 AM » |
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Have had Cobra's on my '98 Standard for 20 years. No re-jetting and it runs fine. O.E.M. air filter always.
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DeathWishBikerDude
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« Reply #13 on: June 23, 2021, 01:10:37 PM » |
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My purple 97 runs perfectly..ever since day one.
Must just be the 97 bigger carb/ bigger cam issues.
Have 2 97's and 2 98's
All 3 bikes I bought used had cobra pipes but they don't run nearly as good as my first factory exhaust setup.
Have you ever ridden any valkyrie besides the one you currently own?
My original bike..serial # 753..runs like a scalded dog!
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