Re-jetting?

[nerider2]

What size of jets are recommended with the Viking pipes? 

From what I've read here, 105 fast jets and 38 slow jets are most common for exhaust mods.

I purchased a 99 interstate with aftermarket pipes.  I am not sure what brand they are, they are a 6 into 2 style.  Looking through the photos, they look like they could be Viking pipes.

The spark plugs are dark so it is running rich.  I've installed a new air filter, rebuilt the petcock, installed a trigger wheel, run a couple tanks with seafoam.  It idles great, full throttle it runs kind of rough.  I am getting 32 MPG.  My last interstate I averaged 40 mpg with stock pipes.

It most have been re-jetted to be running rich.  I am down to re-jetting.  Any ideas?

Thanks
Ed

[Patrick]

The 38 lows are generally for those that have had varnished 35s.. The standard highs are 100s which run a tad rich with factory pipes.. I don't think most guys are re-jetting with most after market pipes,, most just move the needles if necesary.. 105s sound pretty rich to me for any changes..

[Black Sled]

I have been down this road.  Others may disagree but my opinion is that unless you modify the stock air box there is no need for larger main jets.  The air box is engineered to limit the air flow at wide open throttle (WOT) to match the stock mains.  Since the Valkyrie power peaks at high RPM, larger mains will effectively result in less peak horsepower as the engine will be running rich at that point.

As Patrick stated, a K&N and/or aftermarket pipes will cause the mid-range to lean, and this is addressed by shimming needles.

The slow jets are a mixed bag - 38's eliminate the need to choke a cold engine, and make a nicer (fatter) exhaust note.  The downside is a modest deterioration in gas milage.  They are just a tad too large but that should buy you some slack if a little varnish does occur.

Hope this helps.
-Sled

[GOOSE]

ed.....just my opinion (you know what they say about opinions?)...i run 105 mains/38 slows with the fuel/air screws turned out 1 1/2 turns...modified exhaust on first valk, same everything, but with cobras on second valk.....both get between 37-40 mpg. 

[Black Sled]

Goose - it sounds like you have a good running bike. I am curious if you have had it dyno'd?

When I was running the same combination I had it dialed in pretty well and thought it was running great.  The dyno confirmed that it was dialed in up to 5200 RPM.  Above that the AFR dropped dramatically and HP curve flattened at 87 HP.  Never would have believed it.  I am back with 100's now.  Lots of trial and error to get there too.

As you know, there is a lean spike at around 3000 rpm and I was tuning to that.  Now that I am back to 100's I have had to fatten up the needles more.

Of course location (elevation) and the specifics of our machines are variables.

[shortleg]

  If in fact they are Viking pipes you should be able to adjust the needles
to lean it out. I have Viking pipes and found them to run just fine[judgeing form
dyno runs] with one step larger mains and adjusting needles.
             Shortleg[Dave]
   Do you have a picture of you pipes, we could then tell you.
 Are they chrome or ceramic coated?

[Piper]

ed.....just my opinion (you know what they say about opinions?)...i run 105 mains/38 slows with the fuel/air screws turned out 1 1/2 turns...modified exhaust on first valk, same everything, but with cobras on second valk.....both get between 37-40 mpg. 

This is what I am running also along with:
Needles set in the middle.
Airbox was modified when I bought her.
k&n air filter
Cobra 6 into 6
total de-smog
mid-grade fuel
Interstate ICM on a Standard.

I get somewhere in the neighborhood of 35-38 mpg.
Not really keeping track, just know that it is a 70 mile
round trip to work and back and it takes less than
two gallons to top her off again.
And I am at a elevation of about 6500 ft.

I could probably get better mileage if I:
Kept better ongoing records.
keep the rpm closer to the 3000 range.
did not have so much fun.
lost a bit of weight, ok more than a bit....

[GOOSE]

blacksled.... along with the 105/38's i run a 6 degree  wheel/ interstate icm (both bikes-tourers). 

[nerider2]

The pipes are chrome, 3 all joining together just behind my heel, where I tend to meld the inside of my soul.  I'll take some photos and post them this weekend.

Thanks

Ed