Howdy,

Here is the chart of my test run on the dyno. No tuning, just a raw run.

Two questions.
1) What about the initial Air/Fuel Ratio at 2,000 RPM? Install new slow jet?

2) The midrange to max RPM is fairly consistent. Should this be richened a bit by a new needle or revised position?

Thanks,

2003 FXD
88 C.I.
Stock heads and intake.
Dynojetted CV
SE Stage 1 Air Cleaner Kit
Super Trapp 2:1 SuperMegs (22 cones)
S&S Cam Gear Drive
Andrews TW-37G cams


[IMG]local://upfiles/20717/FCD254684837497BA0B3A42474FB8CC3.jpg[/IMG]

 

1. Yes, I would change the slow jet to 1 size richer.

2. Unless you have no adjustment left (are already at the richest clip position) you should not need a new needle. Just raise the needle one position to make it richer. I think one position on the needle will be pretty close to where you want it to be.

 

It seems to me that Dyno runs are made a Wide Open Throttle -- the only thing you'll be able to tell from a Dyno Run is whether or not the main jet is correct. Looking at the chart, the AFR doesn't look too bad. I would suspect that the leaness at the beginning is an artifact of throttle being whacked open suddenly at the start of the run.

A dyno chart won't tell you anything about your slow or intermediate jetting. If you check the Mikuni site (www.mikuni.com) and find the Mikuni 42mm tuning manual they have posted, it will be very enlightening in general concerning how to tune the slow and midrange jetting.

What bike is this -- is it a stocker with CV carb, or modified? From the chart it looks like you might have some intake/exhaust mods. What jetting do you have now, stock?

 

Oops -- didn't see your list of mods before I posted my previous reply. From your list of Mods I'd say you've got about all you're going to get from an 88". I noticed you Dyno-jetted the Stock CV -- the Dynojet kit is generally known to be set up pretty rich with a resulting drop in gas mileage (my personal preference is the Mikuni 42mm, but that a lot more $$). The real question on Carb tuning is the driveability -- how easy does it start and how does it feel a low speed and roll ons? Does it warm up quick or do you need to keep the choke on for awhile?

 

Thanks for the replies!

The local Harley shop did the dynojetting, This was done prior to my picking up the bike new in March of 2003. At the time I also had installed V&H ShortShots and the SE Stage 1 Air Cleaner Kit. The ShortShots were a disaster in that the rear support bracket broke 5 times in a year and a half. They were zhit canned in Sturgis in 2004 after breaking a newly installed bracket just befor leaving PA on the ride to Sturgis.

At the inital dynojetting the Harley Tech stated that my bike needed bigger jetting than any other bike he had worked on before. The plugs always looked good, no matter what exhaust I had on the bike.(I am on my third exhaust).

A buddy of mine on his Honda Spirit 1100cc bike and I did a trip to the "Tail of The Dragon" in 2005. At every fillup I beat his fuel usage by a small margin. I was really reving my beast through the twisties while he was much more conservative. The mileage out of my bike surprised he and I, and also pissed him off a bit.

Since the plugs looked good, I never took the carb off to mod anymore so I do not know the exact jetting currently in the carb. This winter I am puling the CV off to see just what is in it's inards and will either modify the slow jet and raise the needle, or just slap on a Mikuni 42.

The bike always ran fine, no popping or backfiring, nice power delivery form take off to hitting the reve limiter. With the dynojet kit I always had to get off the choke quick or she would load up. That was the only drawback to the install.

I plan on upgrading to a 98" (not a typo) later next year. The cylinder assembly and piston will make the 98", with SE HTCC Ported Heads in the top end also. This is why I might spring for the Mikuni. As always, finances will dictate just when the upgrade to 98 incher will actually occurr.

 

If the bike starts, runs fine, and gets 40mpg or better in normal driving then I wouldn't mess with the jetting until you get ready to do your upgrades. You'll like the Mikuni 42mm, but it can be a pain getting the cables routed so they operatev smoothly without binding --- the carb response is like night and day compared to the CV. The Mikuni has a lot more instant response.

When you upgrade to 98" I believe you're going to use the Millenium Cylinders that have a very thin (if any) liner with a special hard coating for the rings to run against -- you might check others experiences with them. I haven't heard anything other than it's hard to get the rings seated initially.

I've got a 95" 2003 FXDL that I've upgraded with SE Heads w/comp releases, 10:1 Forged Pistons, Mikuni 42mm, Woods TW6HG Gear Drive Cam, S&S IST Ignition, Fatcat 2 to 1 exhaust, 3 tooth smaller transmission pulley, Denso Iridium Spark plugs. My last dyno chart showed 104hp/106tq and I still get 40mpg in normal driving. When it comes time for your upgrade, you should seriously consider a Woods Cam -- they are hard to beat for high torque and horsepower down low where you can use it.

 

Again, Thanks for the replies!

Here is a link to a series of posts regarding the 98" upgrade.

https://www.hdforums.com/m_157906/tm.htm

This thread, as well as my local Harley shops Service Manager's advice, were the deciding factor's in the decision to make it a 98 incher instead of a 95". Heat dissapation and quality of the components cannot be beat as far as I am concerned. My local shop has done enough of the 98" kit to satisfy my doubts.

On another note, the bragging rights of having a 98 incher as opposed to the more common 95 incher will be an added benefit!![sm=bling.gif]

The shop recommended 45 Mikuni for the project, but I am debating the wisdom of that at this point. I may just richen up the CV this winter to get another dyno run in prior to the 98 inch install.

 

Finally had a chance to pull the carb and check the jetting.

Jettingat time of dyno run:

Slow: 48
Main: 200

I suspect, but can't confirm that the service mechanic installed the lighter DynoJet spring and emulsion tube. I believe I am going to leave the slow jet as is and replace the spring to the stiffer factory spring. I am going to go to a 205 main though.

Any thoughts?

Dyno Run with 48 and 200


[IMG]local://upfiles/20717/19CC6C2348FE4AF099011B5F0289F5AE.jpg[/IMG]

 

I'm not that familiar with setting up the CV -- never really liked them compared to the Mikuni due to the difference in throttle response. I think you'll need to do a seat of the pants comparison on the jetting, although the main will only show up at WOT or on the dyno. If it runs good now I'd just wait til you do your 98" and switch to a Mikuni 42.

 

Some posters have suggested that you just wait till you do your mods. Considering how much work it is to dial-in a carb (unless you pay someone to do it), I agree. As long as it's running well and your plugs don't show an excessively lean condition, just leave well enough alone and dial it in when you do your mods.

Z