HarleyTechTalk

Hi folks,

After being happy with my softail for the last couple of years (hence no posting just lurking), I figured out that I would follow a dream an buy a FXR. After a long wait, a 1993 FXR found its way into the garage and its bone stock 

So, even though there is a lot do be done to it, I figured I better start out with a typical stage 1 kit. It is April and its a short season ... I got hold of a Bassani 2 into 1, Arlen Ness big sucker and a Dynojet Recalibration Jt Kit - 8102.

So here comes the question: I followed the instructions and placed the C clip at the 4 th grove and fitted a 180 main jet. But, what do I do with the low jet pilot? it is currently a 42.

Do I keep it a 42 since the C clip is at the 4th grove? Or should I go ahead and buy a 45 jet (and still keep the c clip at the 4th grove)?

I am pretty sure I put a 45 in my softail and I do think I put the C clip at the 3rd grove there ... This is damn confusing, so I hope you guys can help me out 

This is what I don't like about DynoJet kits.

You have to look at what you are changing and WHY!

The stock carbs actually work very well and need only minor tweaks.

The low speed jet is a very important jet and the first one I change.
The effect of the low speed jet extends beyond the low range and adds to the total fuel flow,
so you want to get it right before making any needle or main jet changes.

That and removing the plug over the idle mix screw.

I'd start with a 45 or 46

I understand what you are getting at ... I might have taken the wrong path here, proably should have settled with buying two jets from our local dealer  ...

But, I used Dynojet's kit on the softail and it has been working perfectly all the time. And the softy is running with Wiseco 10:1 and EV27. Even drilled the famous hole. And it still works 

But, I guess I'll just follow the instructions, and leave the 42 pilot jet, I guess the fact that the needle is raised by one "click" is Dynojet's answer to the 44 pilot jet?

Raising the needle does absolutely nothing for IDLE and transfer fuel.

DJ does not want to get sued for supplying non-C.A.R.B. approved stuff, so that may be why a low speed jet is not supplied.

Often only a low speed jet is needed.

The stock needle can be shimmed, drilling the slide may not do what you want, it changes the speed at which the slide opens.

I would go with the 45 jet, adjust the idle using the idle mixture screw and the throttle stop screw to set it properly, then start working with the needle and it's settings. The needle will affect mileage quite a bit if it is too rich. The main jet may or may not need to be changed, that will have to determined by riding it and testing it old school style.

"Bone stock"! I don't understand what you were trying to accomplish with the Dynojet kit. The Twinky carbs typically came with the 44-45 slow jet, Stg 1, I'd doubt you would need the 46, which is hard to find, start with the idle mix screw & "find out" if you need to go up on the slow jet, by using the enrichner.
By shimming the jet needle you started on the wrong end first. Drilling the slide is just a No,No in my books & makes for difficult tuning.

drilling the slide ..... theres alot of carbs out there that have been "dyno-ed" then onto ebay they go .

Quote from: koko3052 on April 23, 2018, 12:13:14 PM
"Bone stock"! I don't understand what you were trying to accomplish with the Dynojet kit. The Twinky carbs typically came with the 44-45 slow jet, Stg 1, I'd doubt you would need the 46, which is hard to find, start with the idle mix screw & "find out" if you need to go up on the slow jet, by using the enrichner.
By shimming the jet needle you started on the wrong end first. Drilling the slide is just a No,No in my books & makes for difficult tuning.

+1 ^^^^^
The CV carb works fine with a stock motor and even when adding an aftermarket air cleaner / filter and a freer flowing 2 into 1 exhaust.  If anything, the only modification it would need is to swap in a Sportster (richer) needle and bump up to a 44 or 45 jet.

Here is a link to great article written by Joe Minton:
http://www.braigasen.com/hd_jetting.htm

My experience with Dynojet is it seems to make the bike run too rich. Plus you have to buy their jets. Stock jets don't fit it. Unless things have changed, the emulsion tube only has like two bleed holes compared to the stocker that has like 10.

Drilling the slide has it's negatives as well. Don't drill the slide.

If it were my bike, I would go with about a 45 slow and a 170 to 175 main with the 1988 sportster or a CVP "special" needle.

If your slow adjustment screw is about two to three full turns out, then your slow jet is about right. If it is less, then go with the next size smaller slow jet, if it is more than three, then go one size larger.

Start with the slow circuit, then work your way up the three circuits for final tuning. Most of the time, a good cleaning, a 45 slow and a 170 to 180 main (range) gets great results. Also a N-65 or CVP "big twin" needle. Maybe a couple of brass washers for shims.

Don't forget the float level plays a role in the game as well. YD

Great success here, with both the Stage I and Stage 7 Dynojet CV carb kits, over the years.
Easy, peasy.

thank you all for chiming in. Its been a few hectic weeks in order to get the FXR running. I did install the 180 main, needle with clip on the 4th groove, and the spring. I dropped drilling the slide for now.

Did a few test runs, everything seemed to work out fine, but when reading the plugs it seemed to run lean. Went do the dealer again today ... and asked for a 45 slow yet. One on the most experienced guys asked me "why". He had never used a 45 on an evo since they got their dynobench years ago ... And he asked me why I hadn't drilled the slide ... Told me to trust the instructions ...  And he also asked if I had checked for an airleak on the intake manifold (which I did today). And by all means ... I found a leak.

So ... I don't find it to funny to mess with the carb when the season is starting and the sun is shining, hence asking for an advice from you guys . I am changing out all O rings on the manifold and getting rid of the leak, but should I go ahead with the 42 or go with the 45 slow jet?

And ... I guess I better drill the slide and follow instructions? Any thoughts? The mechanic at the dealer was right about the leak, and that makes me wonder if he is also correct about the rest (42 slow and drill the slide).

Looking forward to getting your thoughts on the matter 

.

Quote from: Panzer71 on May 15, 2018, 12:36:12 PM
thank you all for chiming in. Its been a few hectic weeks in order to get the FXR running. I did install the 180 main, needle with clip on the 4th groove, and the spring. I dropped drilling the slide for now.

Did a few test runs, everything seemed to work out fine, but when reading the plugs it seemed to run lean. Went do the dealer again today ... and asked for a 45 slow yet. One on the most experienced guys asked me "why". He had never used a 45 on an evo since they got their dynobench years ago ... And he asked me why I hadn't drilled the slide ... Told me to trust the instructions ...  And he also asked if I had checked for an airleak on the intake manifold (which I did today). And by all means ... I found a leak.

So ... I don't find it to funny to mess with the carb when the season is starting and the sun is shining, hence asking for an advice from you guys . I am changing out all O rings on the manifold and getting rid of the leak, but should I go ahead with the 42 or go with the 45 slow jet?

And ... I guess I better drill the slide and follow instructions? Any thoughts? The mechanic at the dealer was right about the leak, and that makes me wonder if he is also correct about the rest (42 slow and drill the slide).

Looking forward to getting your thoughts on the matter 

Go with a 45 slow & leave the slide alone.

Whatever you do, DO ONE THING AT A TIME & CHECK THE RESULTS! If you do half a dozen "modifications" all at once & it turns into a crock of  , you'll be chasing your tail forever.

also... don't forget that the HD 170 jet for example is not the same size as the Dynoject 170 jet... you need to find the look-up table to relate jets in all systems to one-another

https://www.google.com/search?q=HD+to+dynojet+cross+reference&client=firefox-b&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiVjbv4morbAhWEIVAKHcTLA8sQ_AUIDCgD&biw=1384&bih=763#imgrc=CTNf0kRn9gnljM:

Almost  bought  one  for  my  97 road  king  parts guy was  a  friend  sold me needle  from  a 1200 sporty and  I  just  jetted accordingly  tuner said  it  was  right  on the  money  had head work  cam etc. Ended  up  with  a  50 low and  200 main. Dealer told  me  that  they  never  changed  the  main ,  dyno  doesn't  lie  lol