Cobra 6 into 6 - power lost

[Heinno]

Hi there

Is it true that a Valkyrie would loose about 8hp if you install a Cobra 6 into 6 exhaust system.

If this is the case, would re-jetting correct the problem and would it lead to a potential increase in power?

Any advice - thanks!

[Heinno]

thanks, which jet kit should I get for the Cobra 6 into 6 pipes?

[John U.]

Sudco or Chapparal have the slow jets, OEM 35s or 38s, I think Chapparal is cheaper. I haven't tried to buy main jets but I think they have them. It would help if you've had them apart and know what they look like. If not, a call to either company will no doubt assure the correct jets.
http://www.chaparral-racing.com/Product/keihin-slow-jet/SD-19005.aspx

[GOOSE]

slow jets =  38.  main jets = 105.  fuel air mixture screws = 1 1/2 turns out.  stock tojo honda needles.

[98valk]

search is your friend 

posted last sept.
http://www.valkyrieforum.com/bbs/index.php/topic,8248.0.html

http://www.valkyrieforum.com/forum/tech_archive.cgi?read=969520

This 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 on 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.

this HP is still down from the stock pipes or almost the same.

[Chrisj CMA]

I believe every bike is different.  I bought my bike with Cobra drag pipes.  There was no rejetting an for a few years I ran it like that. The only thing was it ran a tad rich and it bugged me.  So I switched to a K&N filter (with pre filter) and now its purrrrrrrfect other Valkyrie owners have ridden my bike and comment it seems peppier than theirs so, if it has a hp loss...noone can tell.  was getting almost 40mpg until the alkeehol gas got here, now Im at 35mpg smooth as glass and fast. 

[98valk]

I believe every bike is different.  I bought my bike with Cobra drag pipes.  There was no rejetting an for a few years I ran it like that. The only thing was it ran a tad rich and it bugged me.  So I switched to a K&N filter (with pre filter) and now its purrrrrrrfect other Valkyrie owners have ridden my bike and comment it seems peppier than theirs so, if it has a hp loss...noone can tell.  was getting almost 40mpg until the alkeehol gas got here, now Im at 35mpg smooth as glass and fast. 

now chrisj, u know every harley is faster and peppier because of the sound 

Per motorcycle consumer news testing of stock bikes. remember every dyno and operator is different which translates into different #s

’97 valkyrie

100 HP 102.3 lb.ft
0-60 3.86 sec
¼ 12.02 sec
wet weight 721 lbs

’99 Tourer

93.2 HP 92.5 lb.ft
0-60 4.12 sec
¼ 12.52 sec
wet weight 776 lbs

’99 Interstate

94.9 HP 92.8 lb.ft
0-60 4.37 sec
¼ 12.76 sec
wet weight 833 lbs

’99 Goldwing

79.7 HP 91.2 lb.ft
0-60 5.26 sec
¼ 13.28 sec
wet weight 912 lbs

[Chrisj CMA]

Well Mr CA.......Mine is a '97 so if my 100HP is now 97HP and still a tad over what the other years are capable of....that would splain it, but it makes no nevermind cause I cant tell.  Ive never had my bike dynod so as far as I know it has its full 100HP...thats my story and Im sticking to it.  LOL

[Westsider]

a lot of people up grade the exhaust system on their trucks/cars/ no one ever rejets the carbs ,at least i never have, or anybody i know has / its a water cooled basicly car engine,, i say  dont worry to much about / re-jetting /  the things rock solid ..and your just putting a set of pipes on..even on air cooled motors the jetting needs very little if any at all  changes ,,a little curb idle/aka pilot/ adjustment thats it.....jmho....and im just sayin...and all that...  thinking your losing hp due to lack of back pressure on cyclinder charges...the nice sound of the pipes is good and you would think its making more power..deciving...

[Heinno]

Thanks to all the info - BTW - if these pipes come with baffels, do one still need the re-jet?


I am quite happy to go from 100hp to 90hp - still way more than a 103 ci Streetglide's 72 hp - LOL!!

[Heinno]

Hi All

If the Cobra 6 into 6 pipes come with baffles, do you still need the re-jet?

Let me know, thanks