Originally Posted by 1/2crazedbikr

Well I finally replaced the intermediate jet on my S&S carb today. Since I am a newbie at all this evo stuff (and I know from this forum that there are plenty more out there like me) I'm always poking around here and other websites looking for help on how to do the latest project or upgrade on the old girl (a 1988 FLHTC).

So for the other newbies out there I thought I would post some pointers and things that I ran into while doing this job.

I've been monkeying around with the idle speed, mixture, and accelerator pump settings for months now, and I think I had it dialed in about as well as it could be. For those of you who don't know, there are excellent videos on SScycles.com, their website. There are even more on youtube, just search youtube for SS carb videos and there are a ton. I followed the instructions on the S&S carb quick guide (on the website) precisely but was still getting quite a bit of coughing through the carb and some stumbling when cruising at 2000-2500 rpm. This is part of the range that the intermediate jet handles, and from what the S&S video on jetting says, it sounded like I was running a bit lean and needed to go up a size on the intermediate jet.

So first I needed to see what size intermediate jet I had in there. To access the jets you don't have to remove the carb from the bike. All you have to do is remove the air cleaner and the backing plate, and then the float bowl. Remember though, before you remove the float bowl, SHUT OFF THE PETCOCK AND DRAIN THE FLOAT BOWL! The drain is right in the middle of the bottom of the float bowl. If you don't shut off the petcock you better have a pretty big bowl handy to catch all the fuel as it drains out of your fuel tank.

Once I had done all that is when I had my first and only problem of the job. The problem was that, in all the posts, instructions and videos I could not find anyone saying where the 4th screw to remove the float bowl was. I spent literally 2 hours with the bike on the lift and on the floor, laying on my back looking up and looking down with my inspection mirror. What they don't tell you is the 4th screw is about 3 inches long, and the others are about 3/4 inch. And the 4th screw is right in the middle of the accelerator pump apparatus at the bottom right corner of the carb. The other screws are where you would expect them to be, where the bowl meets the carb body. Then, once I decided it HAD to be one of the screws around the accelerator pump stuff at the BOTTOM of the float bowl, I had to figure out which one. My motto when doing any do it yourself project is "first do no harm", (like the Hippocratic oath- I'm an RN) so I always try to be absolutely certain what I'm doing before I tear into something. Anyway, if you look at the screws in that area, you can tell that some hold on the accelerator pump cover, and one does not. That's the 4th and last float bowl screw. Once I finally figured that out it was smooth sailing.

I pulled out the intermediate jet (it was a .028 I believe). The S&S jetting video http://www.youtube.com/watch?v=I_uH72wDTL0 shows you which one it is. I hope the link works. If not it's easy to find on youtube. I then hopped on my other bike (sorry guys, a yamaha) and rode up to JP cycles in Destination Daytona and picked up the next 2 sizes up.

By that time the day was shot and I decided to leave it for today. The rest of the job the next day took maybe 2 hours tops. I did what you could call a "light rebuild" while was into the carb. The installation instructions for the SS Super E carbhttp://www.sscycle.com/uploads/instructions/51-1012_carb_e_&_g_series_shorty_carburetors_installa tion.pdf , also found on their website, is a big help for this. It has everything from float settings to recommeded jets, to how to actually tune the carb after changing jets. I basically removed and cleaned everthing that air and fuel pass through that is accessible by removing the float bowl. I also checked the float height, it was fine. I also sprayed the needle valve with carb cleaner but didn't remove it. I plan on doing a full carb rebuild in the future-I'll replace the needle valve then. I also unscrewed the Idle mixture needle and cleaned it and replaced it. I also noticed there was an O ring missing on the ejector nozzle tube. This the tube that sprays from the accelerator pump into the carb throat when you are hard on the throttle. I had heard that if this O ring is missing you'll never get the bike running just right. JP had one of those too. So I replaced that. I also pulled and cleaned the emulsifier tube. That is the tube that holds the main jet. I could not remove the main jet because the screwdiver slot was all worn out. So I just cleaned it the best I could with carb cleaner and blew it out with compressed air. Did the same with the other orifices and passages.

Anyway, it was a very simple, straightforward job once I found the 4th float bowl screw. Replacing the intermediate jet was simple, you unscrew the old one and screw the new one back in the same hole. Nothing to it.

You then have to retune the carb, which is really very simple. First you reset the carb to factory settings, which are found in the S&S carb quick guide on their website. Then start the bike and ride it, to make sure you are tuning your carb when the bike is fully warmed up, otherwise it will run too rich when it is warmed up. Once the bike is warmed up turn off your accelerator pump before you set your idle speed. The accelerator pump will affect your idle speed, so the instructions say to shut it off first. Do that by turning in the accelerator pump adjustment screw until it seats. Don't go any further, you can crack the carb body. Then set your idle speed to about 900-1000 rpm (I know, it doesn't sound as cool that high) but you'll be moving more oil and off idle response will be quicker then if it's set lower. After that you set your idle mixture following the jetting video or carb quick guide video. After you set your mixture, check your idle speed, it has probably changed, so set it back to 900-1000.

After that adjust your accelerator pump according to the video. This is the fun part because you get to crack the throttle a whole bunch of times. Just don't get your head too close to the carb throat to see what goes on in there while your cracking the throttle-that is if you like the way your eyebrows look. First time she backfires out the carb when your adjusting the accelerator pump you'll see why.

Then you'll probably want to reset your idle speed one last time because again, it probably changed.

That's all there is to it, except the fun part. Taking it for a test ride to see if your changes accomplished what you hoped. You may have to monkey with different sized jets to get the desired results. I went one size up from the .028 (up to .0295 I think) and she runs like a scalded ape now. And she ran pretty awesome before that too, only now she runs even better.

My "testride" streched into a 100 mile loop today (sorry to all y'all Yankees in the frozen north) after the rejetting and she didn't cough through the carb even once. The 2000-2500 rpm zone is wwwaaayyy smoother with no sputtering, she's just a little flat in the torque curve in that area. But hopefully one of these days I'll slip in an EV27 cam to liven that up a little bit. But that's for another day.

I know this has been long winded and this is all old hat to most of you guys, but to all you newbies out there I hope this gave you a little info you can use. Just remember S&Scycles.com and S&S videos on youtube. I hope my links work but if they don't I'm sorry. I'm a male nurse not a computer guy (or a mechanic for that matter).

Ride Safe,(or pleasant dreams until spring)

Originally Posted by OddJack

Great write up, except the instructions say set idle first not shut off accelerator pump screw first

Just for someone who may search and stumble upon this thread.

Originally Posted by Max Headflow

Old thread but since you brought it up.

There are a couple mistakes..




This is wrong.. See the video.. The accel pump has no effect on the idle. It only screws with setting the int jet. You really want to shut it off an putt around at small throttle openings to get the size if the int jet right.

The issue with the changing the int jet is that it affects the idle mixture. It will affect idle speed when changed because the mixture was off. The guy was correct in his jetting change tho. It's mentioned in the video, You want the smallest int jet where the bike runs fine.

The video itself is very good. The only argument I'd have is that the SnS guy says the int jet only affects up to 2500 RPM.. IMO it really more the affect it has based on throttle position which he mentions later. Notice that once they start doing full throttle runs on the dyno, it's all main jet and air bleed. Int jet has no effect.

BTW, notice that it goes a little lean at 4500. That could be fixed with a Tjet.

Originally Posted by 98hotrodfatboy

Agree, the Int jet should be as small as possible to maintain a good smooth idle with the mixture screw approximately 1.5 turns out from lightly seated and again correct on the accelerator pump.. You should never try to tune a carb with the accelerator pump active..
As for the RPM range of the Int jet, that is really controlled by Air bleed jet for the Main jet. A .040 will allow the main jet to come inn around 2700-2800 rpm. The bigger the Air Bleed jet the later the Main jet will come in.. However it's best to use an AFR meter to really see the cross over point.
As for the Int jet circuit yes it controls the fuel mixture at idle but the circuit never stops drawing fuel throughout the entire RPM range. when your cross over point to the main jet is reached it will add fuel along with the Int jet. And yes if your going lean at 4500 you could experiment with a larger main or add a Thunder-Jet... 3 fuel circuits are a nice way to smooth out the AFR's but again it's best done on a Dyno or with an AFR gauge... You can data log to see the true adjustments.

Originally Posted by 98hotrodfatboy

You can look at it in any way you want but as long as you have a drop in atmospheric in the venturi fuels going to be forced up through both jets because atmospheric is lower in the Venturi and greater in the bowl, hence the bowl vent . That's when the greater atmospheric pressure in the bowl is pushing down on the fuel in the bowl forcing it through both jets..