ONE SICK VALK!!!

[BIG--T]

If a person put Cobras on and did not rejet, what  could he expect? how would it run?

Thanks  Will it decrease performance dramaticly?

[R J]

Several people have run Cobra's 6X6 and never rejeted.

Mine ran like a scolded dog, but the drone on road trips about drove my brains out the top of my head.      Didn't want to lose anymore as didn't have to much to start with.   

So I went with Viking exhaust system.    Been on there for about 9 or 10 years now.

[BIG--T]

Thanks RJ, The guy I bought the bike from said he "thought" the original owner rejetted so I don't really know without tearing into the carbs and don't want to do that.

The reason I ask is because and have posted this before, she is a sick puppy! It is fast through the gears but when she hits 75 or 80 all at WOT she starts slowing down and seems to take forever to hit 100. When I back off the throttle a hair it seems to pick up a little speed.

My VTX 1800 will eat it for breakfast!! I know it's almost  300cc more but from all I read from reputable sites like Motorcycle Cruiser and others, they both turn in the mid 12'S @ 105 mph. Now my X is strong and have outrun other 1800'S..but it shouldn't be that much stronger than my Valk.  Either I just have a sick Valk from the factory (had cars like that) or there's something wrong with it and I hope it's the latter. 

[biguglyman]

Guy I bought mine from had the 6x6 Cobras installed and they replaced needles and springs and re-jetted.  Runs great.  Find a shop nearby that has a dyno and let them tune it.  That's what he did.

[BIG--T]

Guy I bought mine from had the 6x6 Cobras installed and they replaced needles and springs and re-jetted.  Runs great.  Find a shop nearby that has a dyno and let them tune it.  That's what he did.

That's good to know but ounds like a lot of $$. The guy that has a dyno here charges around $500 a pop and some say the reader is not accurate.

[VegasF6]

I guess I can't speak for your area, but I would be surprised at  price like that. More typicaly in my experience is $100 for 3 runs. It's not unusual for dyno owners to offer a track day or tune day through local motorcycle or car clubs as well, you will hear about them having unlimited testing for X amount of dollars. I thought South Carolina was race country? Check with your local or nearby track for some recommendations.

As to the accuracy, well, dyno results can vary between machines, and even some just by the weather. So, while you may test 85 hp at such and such RPM on one machine, it may change by a couple hp or more on another.

That really doesn't matter when you are tuning, and that is the real reason for a dyno test in my opinion. A dyno WITH an exhaust gas analyzer (make sure of that) will show you before and after power, but more importantly it will show you flat spots or dips that indicate you have a problem. A heck of a lot more accurate than tune by ear and read your spark plugs 

[Daniel Meyer]

Have you checked the petcock? Sounds like fuel starvation to me.

[Patrick]

I agree with Daniel.. I think I'd check the fuel delivery.. Also, I think most that add those pipes change or raise the needles.. I don't think re-jetting is needed,but, anything can happen..

[Mildew]

They don't require rejettin. I actually gained a few mpg

[rodeo1]

jeeze guys, stop sending everyone scampering to the petcock every time they have a fuel problem, OEM petcocks seldom give us any "real" problem.

check the overflow hose that runs out of the back of the tank first and see if its clogged, or more common crimped off a bit, this needs to be completely open. then if nothing is found check out the petcock. but first, look at the line coming from #6 real close, heck replace it, its super easy to do. if it is cracked and the vaccum to the petcock is shut partially down, you could concevably have a starvation issue at high speed. cobra pipes, like all straght pipes have more effect on the low end torque than the high end speed.

[Daniel Meyer]

jeeze guys, stop sending everyone scampering to the petcock every time they have a fuel problem, OEM petcocks seldom give us any "real" problem.

I disagree. I fixed 12 of them at one Inzane (1st Paducah I think). Pretty much everybody that had a power or mileage complaint had a bad petcock and rebuilding it cured the problem.

I've run out of kits every year since. If they weren't so expensive I'd give 'em away like Halloween candy.  

If they get attention every year or so they cause no problems...but many haven't been touched since new (some for a decade!)

[The Anvil]

If they get attention every year or so they cause no problems...but many haven't been touched since new (some for a decade!)

Which is the way it should be.

[BIG--T]

I guess I can't speak for your area, but I would be surprised at  price like that. More typicaly in my experience is $100 for 3 runs. It's not unusual for dyno owners to offer a track day or tune day through local motorcycle or car clubs as well, you will hear about them having unlimited testing for X amount of dollars. I thought South Carolina was race country? Check with your local or nearby track for some recommendations.

As to the accuracy, well, dyno results can vary between machines, and even some just by the weather. So, while you may test 85 hp at such and such RPM on one machine, it may change by a couple hp or more on another.

That really doesn't matter when you are tuning, and that is the real reason for a dyno test in my opinion. A dyno WITH an exhaust gas analyzer (make sure of that) will show you before and after power, but more importantly it will show you flat spots or dips that indicate you have a problem. A heck of a lot more accurate than tune by ear and read your spark plugs 

Thanks Vegas I'll check it out.

[BIG--T]

Have you checked the petcock? Sounds like fuel starvation to me.

It is strong up to 80 and if it was a starvation issue, wouldn't it be slow to 80?

As far as the petcock it is OEM and only has 11k on the clock. How would I check the petcock? The off,on, and reserve work and no smell of gas and no leaks.

Thanks, Tony

[Daniel Meyer]

Have you checked the petcock? Sounds like fuel starvation to me.

It is strong up to 80 and if it was a starvation issue, wouldn't it be slow to 80?

As far as the petcock it is OEM and only has 11k on the clock. How would I check the petcock? The off,on, and reserve work and no smell of gas and no leaks.

Thanks, Tony

Pull a vacuum on the vacuum port on the petcock, it should hold and not leak down vacuum. (simplest test).

If it's leaking vacuum, it's not opening fully and at high rpm/loads not enough fuel is flowing AND the vacuum is less so it's open less, plus, you've got a vacuum leak on top of it.

[BIG--T]

Have you checked the petcock? Sounds like fuel starvation to me.

It is strong up to 80 and if it was a starvation issue, wouldn't it be slow to 80?

As far as the petcock it is OEM and only has 11k on the clock. How would I check the petcock? The off,on, and reserve work and no smell of gas and no leaks.

Thanks, Tony

Thanks I'll try that.

Pull a vacuum on the vacuum port on the petcock, it should hold and not leak down vacuum. (simplest test).

If it's leaking vacuum, it's not opening fully and at high rpm/loads not enough fuel is flowing AND the vacuum is less so it's open less, plus, you've got a vacuum leak on top of it.

[hubcapsc]

If you decide to rebuild your petcock, I've rebuilt several, I'd be glad to be on hand for the event...

-Mike

[BIG--T]

If you decide to rebuild your petcock, I've rebuilt several, I'd be glad to be on hand for the event...

-Mike

Thanks Mike, I would really appreciate that! Do you have a way to check the vacuum?

Tony

[hubcapsc]

If you decide to rebuild your petcock, I've rebuilt several, I'd be glad to be on hand for the event...

-Mike

Thanks Mike, I would really appreciate that! Do you have a way to check the vacuum?

Tony

I use the vacuum test in this shoptalk article after I've rebuilt a petcock to help insure that I did it
right before putting all that stuff back together...

http://www.valkyrieriders.com/shoptalk/petcock.htm

I think the other folks on this thread suspect you have  a tiny pinhole somewhere in your diaphragm,
and the test they're suggesting is something like using a mity-vac (or something) to suck a vacuum
at the same orifice they use in the shoptalk article I referenced, and then coming back later (a couple of minutes?
 an hour?) to see if the vacuum held, or leaked down...

If you create your vacuum with a machine (like a mity-vac) you probably want to set the machine on
"stun" instead of "kill" - it doesn't take much to flip the little valve down in the fuel outlet...

-Mike

[BIG--T]

If you decide to rebuild your petcock, I've rebuilt several, I'd be glad to be on hand for the event...

-Mike

Thanks Mike, I would really appreciate that! Do you have a way to check the vacuum?

Tony

I use the vacuum test in this shoptalk article after I've rebuilt a petcock to help insure that I did it
right before putting all that stuff back together...

http://www.valkyrieriders.com/shoptalk/petcock.htm

I think the other folks on this thread suspect you have  a tiny pinhole somewhere in your diaphragm,
and the test they're suggesting is something like using a mity-vac (or something) to suck a vacuum
at the same orifice they use in the shoptalk article I referenced, and then coming back later (a couple of minutes?
 an hour?) to see if the vacuum held, or leaked down...

If you create your vacuum with a machine (like a mity-vac) you probably want to set the machine on
"stun" instead of "kill" - it doesn't take much to flip the little valve down in the fuel outlet...

-Mike

Not to sound ignorant, but rather than rebuild first wouldn't I want to do a vacuum check first to check the petcock?

thanks

[The Anvil]

If you decide to rebuild your petcock, I've rebuilt several, I'd be glad to be on hand for the event...

-Mike

Thanks Mike, I would really appreciate that! Do you have a way to check the vacuum?

Tony

I use the vacuum test in this shoptalk article after I've rebuilt a petcock to help insure that I did it
right before putting all that stuff back together...

http://www.valkyrieriders.com/shoptalk/petcock.htm

I think the other folks on this thread suspect you have  a tiny pinhole somewhere in your diaphragm,
and the test they're suggesting is something like using a mity-vac (or something) to suck a vacuum
at the same orifice they use in the shoptalk article I referenced, and then coming back later (a couple of minutes?
 an hour?) to see if the vacuum held, or leaked down...

If you create your vacuum with a machine (like a mity-vac) you probably want to set the machine on
"stun" instead of "kill" - it doesn't take much to flip the little valve down in the fuel outlet...

-Mike

Not to sound ignorant, but rather than rebuild first wouldn't I want to do a vacuum check first to check the petcock?

thanks

You don't completely rebuild things as a preventative measure? You obviously don't work for the government.