Hello folks:

I just bought my first Sportster and I have questions concerning the carb. I live at 4000 feet and my machine is a 1974 Sportster XLH (1000cc). The dude I purchased it from had already relpaced the original carb with a new S&S Shorty (not sure if it is an "E" or "G").

My problem is this: the bike has no top-end acceleration.....low-end and mid-range are fine but the revs max out way to early making me believe that the main-jet is too small.

Now, when I say "main-jet" I am using my knowledge and "lingo" from 20 years of working on and rebuilding Mikuni BS (CV) carbs.

The issue I have is that I have never opened up an S&S carb and I'm not even sure that the term "main-jet" applies to the S&S carb.

CAn someone advise me?? Any place on the net where I can find a schematic/diagram of the S&S carb? Can anyone give any suggestions as to what size the jet should be? Where can I purchase a new jet or set of jets?

I have worked on motorcycle carbs for half of my life but I'm not sure where to start on my Sportster.

PLease help if you can: thanks much for any replies: DTKid

 

You don't have to pull the whole bowl off to do the main jet. There is a big brass "plug" looking thing on the bottom of the S&S bowl. Take that out (5/8", if I recall) and under that is the main jet. Use either the special S&S mainjet tool or a stubby large flat blade screwdrive to unscrew it.

I bet that your too fat, not too lean on that jet. I fought an S&S Shorty on an 883 and finally got it jetted about as good as it would do, but it was a biatch to do. Take it for a ride, get it up to operating temp, make a high speed/power run where you think it is not right and shut off the kill switch while it is there, pull in the clutch and coast to the side of the road (do this in a safe area, of course). Pull the front plug and see if it is black or white or tan. Black=too fat. Or, keep putting in smaller jets until it runs like crap and spits/pops, then go one bigger.

In my opinion, the S&S' are just too big for the 883, regardless of the fact they they sell a kit specifically for one. I don't know if a 1000 has enough air flow to be any better there or not. A better carb would be about a 32 to 34 Mikuni, I think, but you can't really find a kit for that anymore. This year, I solved all the Sporty's carb issues by converting it to fuel injection. Runs fantastic now.

 

Oh, and the S&S web page: http://www.sscycle.com/
has PDF's of all kinds of stuff. They should have one for your carb. You can get jets at virtually every Harley and especially aftermarket shop in the country. Pull what you have in there out first so you know where you are starting from, if somone hasn't bored it out with the next larger drill bit yet. There are 3 jets in the S&S: The idle adjustment screw, the intermediate jet and the main jet. The idle and intermediate jet circuits runs the bike most of the time, with the main only coming on at high RPM and throttle conditions.

I have developed a real hate for carbs.

 

Hey Doc:

Thanks a bunch for the detailed reply. I checked out your web-site; nice. I'm a College Prof. with a Ph.D. in Physiology & Biophysics. I have plenty of time to tinker because I'm not in research any longer. I just teach a few classes a day and go home to my machines and kids.

I never could see myself working as hard as you Physicians/Surgeons. Of course I'm always broke!

I'm a bit of an expert on the Mikuni CV-carbs (I've got 7 old Suzukis) but I didn't quite know where to start on the S&S. You provided me with exactly what I needed.

Thanks for the help.........Good Luck Saving Lives: David (Dr. Kid)