Changed exhaust, crappy mileage

[cogsman]

Swapped out my TBRs for stock exhaust. Love the smoothness and quiet of the change lol

Not loving the mileage! I have the larger tank and with my TBRs I was getting 280km out of a tank. Now after my first tank with the new pipes I only managed 230km!!

What gives and is there anything I can do?

[sandy]

With the stock exhaust, you probably have more backpressure. Has caused a rich condition. Pull the tops of the carbs and see if you have Dyna Jet needles. Lower the circlip to the 2nd notch from the top. It'll lean the running mixture ratio. If you have stock needles, they may have an extra washer under them. If so, leave only the thin washer and replace the needle.

[cogsman]

Ok, this is something I will do in a few weeks once riding season is over.

How do I know if I have Dyna jet needles, and then I guess the next logical question is what do I do if I DON'T have Dyna jets?

[98valk]

Ok, this is something I will do in a few weeks once riding season is over.

How do I know if I have Dyna jet needles, and then I guess the next logical question is what do I do if I DON'T have Dyna jets?

they are not Jets, they are needles.  u just pop off the top of the carbs.   ALL aftermarket needles are adjustable, oem are not. OEM only one washer should be under the clip.   Aftermarket is most likely what u have just raise the clip which will lower the needle increasing mpg. stock pipes u want the clip one position from the top.

[cogsman]

I've seen a great video on YouTube about removing and servicing the carbs. Quite involved for sure, but looks like fun.

When you say "pop of the top of the carbs", is this something that can be done with the carb rack on the bike, or do I still have to remove it?

Sorry if that's a basic question; I have no experience with this so it's all new to me.

[Pete]

When you say "pop of the top of the carbs", is this something that can be done with the carb rack on the bike, or do I still have to remove it?

Yes just the top chrome covers 4 screws each. Do not remove the carbs.

[98valk]

When you say "pop of the top of the carbs", is this something that can be done with the carb rack on the bike, or do I still have to remove it?

carbs stay in place. usually left side choke cable side the chrome cover has to be removed to allow removal of covers, right side the cover is not a problem.

[hubcapsc]

they are not Jets, they are needles.

Needle jets 

-Mike

[98valk]

they are not Jets, they are needles.

Needle jets 

-Mike

Needle jet is what the needle goes into, two different parts.

http://www.johnsmotorcycleparts.com/keihin-cv-carburetor-images.htm

http://www.cv-performance.com/cvp-needle-jet/

[hubcapsc]

they are not Jets, they are needles.

Needle jets 

-Mike

Needle jet is what the needle goes into, two different parts.

http://www.johnsmotorcycleparts.com/keihin-cv-carburetor-images.htm

http://www.cv-performance.com/cvp-needle-jet/

Those links you posted are pretty specific in their agreement with you...



If you google "needle jet" and look at the returned images, there's overwhelming agreement
with you.

Honda calls the part you refer to  the "needle jet holder"...

-Mike "Oh, Noooo, I'm so sorry. It's the MOOPS. The correct answer is, The MOOPS."

[cogsman]

Hi All,

Okay, I'm ready to make the adjustment. I pulled the carb top off... and here it is...



I have no idea what I'm supposed to do next. Can anyone guide me?

[Steel cowboy]

Pull the diapham up and out of the carb. The jet needle will be attached to the button part of that diapham. Looking at your carb spring it appears to have rust ??

[98valk]

using one of the carb top screws, screw it into the center threaded hole of the diaphragm, and pull the center assembly out which will allow the needle to be removed. check shop talk, there are pics and details.

[cogsman]

Ok I pulled the assembly out (diaphragm, plastic housing, needle) but it's all one piece. I checked shop talk, but I can't seem to find any articles relating to removing the needle.

Does the modification I need to do take place within that black housing I just pulled out? I don't see how to disassemble it.

[indybobm]

In case you do not have it, here is the link for the downloadable Honda Service Manual from Dag in Norway.

http://valkyrienorway.com/download.html

Look at page 5-10 and 5-11. It will explain the procedure.

[cogsman]

Thanks Indy. I actually tried pulling by the screw as it says but it wouldn't budge and I was afraid to break it. I'll try again.

[98valk]

Thanks Indy. I actually tried pulling by the screw as it says but it wouldn't budge and I was afraid to break it. I'll try again.

there is an o-ring in there, so a good straight pull is needed.

[Pappy!]

By chance.....was the previous load of fuel you had in the bike from earlier in the season?
Fresh fuel used for your latest trip could and should be winter blend fuel compared to what may be summer blend left in the tank. Summer blend definitely produces better mileage. Winter blend is a sure case for reduced mileage. Think about it before tearing into the carbs.

[cogsman]

Ok, I pulled it. A lot easier than I thought, thanks for the guidance!

Here is the needle. Does anyone know what I'm looking at? If this is a Dynajet needle, then it looks like the washer is already set one from the top...



I have not yet checked the others, but if they all end up being the same, any suggestions?

[Bagger John - #3785]

Ok, I pulled it. A lot easier than I thought, thanks for the guidance!

Here is the needle. Does anyone know what I'm looking at? If this is a Dynajet needle, then it looks like the washer is already set one from the top...



I have not yet checked the others, but if they all end up being the same, any suggestions?

Put the jet needle in the top groove.

But:

In case it's been overlooked:

How many turns out from seated are the pilot screws?

And...what size idle/main jets have been fitted?

[cogsman]

I have no idea what's been fitted. This is as much a voyage of discovery for me as it is for you 

I'm not intending to do any further work (beyond adjusting the needle) on the carbs.

If the mileage doesn't improve I'll just bite the bullet and bring it to a proper mechanic.

[98valk]

look like factory pro needles

http://www.valkyrieforum.com/bbs/index.php/topic,65465.0.html

[cogsman]

To clean the varnish off the needle. .. can I user carb cleaner? I'm not going to touch anything made of rubber.

[Ricky-D]

If you are trying to get to the correct mpg figures for the stock Valkyrie you should replace the aftermarket needles with

OEM needles. The needles are not the same and will not yield identical results as OEM. Insure you have stock OEM

#100 main jets.  These two items will, when stock configuration, yield you the best mpg results. Adjustment of the

slow speed (idle) screws have minimal affect on mpg figures. 1-3/4 turns out from lightly seated is the nominal setting.

***

[cogsman]

I appreciate that Ricky. I'm not going to go through all of that right now. Essentially I went from 300km a tank on the TBRs to 240km a tank on the Stocks. I'm just looking to up that range, not necessarily match OEM numbers. If leaning the mixture (which is, I believe what this adjustment aims to do) will help me achieve better range, I'm in.

Maybe at some point in the future I will re-jet, but not now.

[cogsman]

I've put the Eclip on the first notch as suggested. Am I correct in assuming that the silver washer just moves freely on the needle?  Or do I have to place it up against the eclip or something?

[98valk]

I've put the Eclip on the first notch as suggested. Am I correct in assuming that the silver washer just moves freely on the needle?  Or do I have to place it up against the eclip or something?

yes.

needles only effect 1/4-3/4 throttle. having the clip on the very top will be too lean, one down from the top is where u want it.
cruising mpg is determined by the pilot jet which is 1/8-1/4 throttle.
open up the idle mixture screw btwn 2-2.5 turns open. this should allow cruise more on the PJ and less on the needle for best mpg.
search my posts. or go the factorypro site and read their tunning section

[Ricky-D]

I've put the Eclip on the first notch as suggested. Am I correct in assuming that the silver washer just moves freely on the needle?  Or do I have to place it up against the eclip or something?

I don't believe the washer to which you refer is part of the aftermarket set-up. Utilizing it will affect the mpg results. It doesn't belong there.

***

[98valk]

I've put the Eclip on the first notch as suggested. Am I correct in assuming that the silver washer just moves freely on the needle?  Or do I have to place it up against the eclip or something?

I don't believe the washer to which you refer is part of the aftermarket set-up. Utilizing it will affect the mpg results. It doesn't belong there.

***

all of the needle kits re-use and install the OEM washer on the new needles.

[cogsman]

I've put the Eclip on the first notch as suggested. Am I correct in assuming that the silver washer just moves freely on the needle?  Or do I have to place it up against the eclip or something?

yes.

needles only effect 1/4-3/4 throttle. having the clip on the very top will be too lean, one down from the top is where u want it.
cruising mpg is determined by the pilot jet which is 1/8-1/4 throttle.
open up the idle mixture screw btwn 2-2.5 turns open. this should allow cruise more on the PJ and less on the needle for best mpg.
search my posts. or go the factorypro site and read their tunning section

Ok, I do appreciate the assistance, though now I'm confused. The thread spoke about leaning out the mixture by moving the clip to the top. Now I'm hearing no, just adjust the one screw...

Let me restate the original problem in case it was lost in the discussion:

I replaced my TBRs with stock exhausts. My mileage dropped 20%. How do I get (some if not all of) my mileage back? I am not going to re-jet my carbs at this time, and probably not at all. My existing needles, which seem to be Factory Pro, are already set at the second notch from the top.

Also, I am hearing that the extra silver washer (see pics above) is ok on the needles. Loose is fine?

And, best way to clean the crud off the needles is Acetone? Laquer Thinner? Carb cleaner?

All help is appreciated. I don't have the experience that many of you do, so I need the Valkyries for Dummies version, sorry.

[98valk]

these carbs have 3 circuits actually 4 if u count the idle circuit. see the factory pro instructions for tuning CV carbs. they all have to blend together for what u want, performance or mpg.
if the needle clip was on the 3 or 4 position from the top then yes putting it on 2nd from top with stock pipes would provide better mpg.
if the TBRs were the 3 into 1 pipes, the oem pipes are less efficient.
the factory pro kit installs one size larger PJs, leave the needle clip 2nd from top only install on washer. adjust the mixture screws. close them by very,very lightly seating them, then open each up 2 turns. 
the oem needles are leaner than the FPs. what ever needle they are the PJ has to be sized and tuned to match that needle for best mpg and smooth acceleration through the gears. all of the circuits over lap each other, the PJ even affects the main jet but usually only noticable high rpm on the track.
I cannot stress enough to read the CV tuning guide if u want the bike to rum like u want.

[cogsman]

Ok, I will have a look. Thank you!

[cogsman]

I finally finished my first tank of gas after some extensive work on the bike. Having moved the circlips to the first notch as suggested here, I am back to 300km from the tank! Thanks everyone!

[98valk]

I finally finished my first tank of gas after some extensive work on the bike. Having moved the circlips to the first notch as suggested here, I am back to 300km from the tank! Thanks everyone!

 

[pancho]

I wonder, after all the years of experimenting, are there any carburetor modifications that  have proven a better state of overall tuning over stock on our bikes when fitted with Cobra exhaust?

[98valk]

I wonder, after all the years of experimenting, are there any carburetor modifications that  have proven a better state of overall tuning over stock on our bikes when fitted with Cobra exhaust?

I've posted this many times over the yrs for cobra owners.

"search is your friend  cooldude

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."

[pancho]

Wow,,  my bike runs great right now with stock jets,, from idle to WOT,, before I opened the jets up that much, I'd rather get a set of stock pipes and see what that did.  I mean if it takes that much fuel flow to make it run like stock, I'd go the other way.... that will be at least 15% worse fuel mileage... 32 to 33 mpg is manageable, but hard enough to live with.

Any personal testimonies on that setup??

Thanks for the response CA, you always seem to have a wealth of info on fuel and oil, but that option is not for me.

[pancho]

I wonder if anyone has tried to modify the Cobra exhaust system to get back the HP??  I mean what is the problem,, not enough back pressure??  can you just pack them up some??

I really don't understand that opening up all the jets as mine seems to burn correctly at all speeds according to plug and plug strap reads with 35s and 100s,, I do have to have the pilot jets out an additional 1/2 to 3/4 to get a good idle.

Anyone looked into this stuff in the past?

[98valk]

I wonder if anyone has tried to modify the Cobra exhaust system to get back the HP??  I mean what is the problem,, not enough back pressure??  can you just pack them up some??

I really don't understand that opening up all the jets as mine seems to burn correctly at all speeds according to plug and plug strap reads with 35s and 100s,, I do have to have the pilot jets out an additional 1/2 to 3/4 to get a good idle.

Anyone looked into this stuff in the past?

they are long drag pipes. drag pipes where developed by HD for their circle track bikes. DPs make more HP in a narrow rpm range than other pipes. circle track the bikes pretty much run an narrow rpm range. this is what I read yrs ago, exhaust pipe design has advanced maybe not all true today.
just google to read more.

[falconbrother]

Lollipops is the answer for drag pipe back pressure in the Harley world.  I'm sure it would work on any drag pipe.  I made my own lollipops on a couple of bikes.  I just welded washers on bolts and installed them.  It offers some back pressure.  I don't think it's as good as a real baffle but..some people like it.