SO i did just buy the bike. (1981 Sportster 1000) knew carb needed some work. it kept Dieing when i'd open throttle up if i ddint baby it. and if i went to far, it'd die. wouldnt idle unless i kept it open a little bit. Tore it apart, Rather clean other then the accelerator pump is like..SHOT! the leather boot thing is dried out and the spring that it uses to hold the leather out is kinda shot too. we cleaned everyting up rather nice and got the leather to soften up. Gonna try puttin some good gas in it tomorrow and see if it helps. After seeing the pump all dried up, it explains why when i'd Juice the throttle, it'd die. Its got a Zenith carb on it? Thats not normal from what i understand and have heard from local HD riders/owners. My One close friend has a CV carb that he said i can have and use as long as i buy an adapter kit for it. NOt sure i wanna go that route JUST YET. If i can get this carb to work, that'd be great..But ill do what i gotta!

Any of yinz got any input on this carb? Or if i should just scrap it and use the CV with teh conversion kit?

Carb is my second most important issue. lol but my biggest NEW FOUND issue is the broken Steering pin that holds tripple clamp together.. Yah.. Thats a BIG PLUS...not. I noticed it today once i got it out on the roads around here at my place.. (crappy roads..bumps, etc etc) i noticed the steering knucle to be moving around.. Thought ahh ok..bearings are shot and ill replace them. Well.. The same dude with the CV carb came out and i told him about it. he looked at it and said "Hmm, the whole knuckle looks like its angled/raked out..maybe its just loose?" so he proceeded to Unbolt the allen bolt thats serves as a pinch bolt for the knuckle pin (ill call it knuckle pin cuz thats best way i can describe it!? lol sorry if i'm wrong on its term) He loosened up the bolt and grabbed hold of the large NUT up top of the knuckle.. He turned it by hand and said WOW its just really loose...after he turned it a few times he didnt notice it tightening at all..he then Picked up/pulled up on the nut. Out came the nut, along with a 1 inch section of the knuckle pin which was threaded..

SO..thats broken. Great. lol On my bike thats a welded, once piece part which requires full disassembly. next is parts...imma search flea bay and local shops to see what i can find. IF IT COMES down to it, ill take the darn thing to work, have it milled out, opened up to a nominal size, and then make my own damn SOLID PIN with matching threads on the end.

So thats my rant. The knuckle pin sucks, but the carb is more important to me at the moment.. lol Yes i cant ride it with a broken pin, but nor can i ride it with a boogered up carb.. So hopefully someone will have some input.

Thanks in advance guys! hope someone has something to say!

 

if your triple tree neck is broke you should replace it before riding, that would be a suicide mission.. you could get one cheap enough on ebay.. as far as the carb goes.. take it to a bike shop to id it, then get a rebuild kit.. if the parts are dryed cracked or worn out, there is no way to revive them.. that is a great carb.. just get it clean and rebuilt..

 

I just remembered that there was article in American Ironhorse Magazine... issue ??? 1/2010 ??? (and XLCR-1000 testdrive) where was rebuild instructions for Keihin butterfly carb...with good pictures

 

Cleaned and Rebuilt myself. WORLD OF DIFFERENCE!! big time difference. I havent rode it yet due to neck stem but just sittin there its a big difference. doesnt stumble, or pop or nuttin. Just pure POWAH!! lol

Now yinz know where to find settings for it?! (i.e. The idle screw, and main jet screw?)

Its an 81 sportser 1000 with Un-baffled Drag pipes. Seems to be just a tad rich when i crank on throttle, although, may just need run also!?

Thanks in advance for any info yinz have!

-Zac

PS. Neck stem is on way...ordered a new one the other night...Cant WAIT TO GET IT IN!! WOOOOO!!

 

For 1981 Sportster with stock Keihin butterfly carb stock jets are main jet : 160, slow jet: 68.

First set the pilot screw and the slow jet following the procedure at the end of this post. Then test the main jet using a WOT [wide open throttle] test. Ask me again about that when you come to it.

It would be very worthwhile to install bolt&washer baffles, also know as lollipops, in the drag pipes. This will get you back some of the lost low end torque, with no loss of the drag pipe loud sound.



The size of the washer is not critical, but about 3/4" OD will work well. The bolt is 1/4" to fit the 1/4" hole that is usually already in pipes a few inches forward of the end, on the inside. If no hole you need to drill one.

Setting The Pilot Screw on Your IronHead

If the carb is old and dirty the pilot screw passage may be gummed up such that you will not be able to "gently seat" the pilot screw reliably. If this is the case remove the carb from the bike and clean it up. Some guys try to do carb work with the carb in the bike. IMO this is a very bad idea.

In the pilot screw passage there should be, in this sequence: screw, spring, washer, o-ring. [Often POs have installed these parts in the wrong sequence; remember that the purpose of the washer is to protect the o-ring from being damaged by the spring]. The screw usually comes out easily. The other parts may require some work. The best technique is to stick a pipe cleaner in the hole, twist it around, and, like magic, out come the other parts on the end of the pipe cleaner.

EDIT: The above info on the pilot screw applies to 1979 and newer carbs. For 78 and older there is nothing in the passage except the screw itself.

1. You need to have easy access to the pilot screw, easy enough to reliably judge "screw it in until gently seated". Loosen the front fuel tank mount bolt; remove the rear fuel tank mount bolt; prop the rear of the fuel tank up on a piece of 2X4; on some bikes this will not be necessary.

2. With the engine cold [so you do not burn your fingers] turn the pilot screw in clockwise until it is gently seated. Count the number of 1/4 turns as you do it; write the number down. Back it out to the original setting. You may need to return reliably to this setting after experimenting.

The "normal" starting point for this process is 1,1/4 [according to the 79 - 85 FM] or 1,1/2 [according to usual practice] turns out.

EDIT: An old HotXL magazine article recommends for Keihin butterfly carbs between 1/4 and 1,1/4 turns out. My experience is that this works best. If you are more than 1,1/4 turns out your pilot jet is too small.

3. The engine must be at full warm up. It will have very hot parts; to avoid burned fingers have a well lighted, comfy place to work.

4. Set the engine idling at about 1000 RPM. You want it to be idling at the slowest speed that is consistent with a smooth idle so that you can hear or feel slight changes.

5. Turn the pilot screw in clockwise until the engine idle becomes worse; tending to stall. Count the number of 1/4 turns as you do this. Then turn the pilot screw out counter clockwise until the engine idle gets good, then becomes worse, tending to stall. Count the number of 1/4 turns as you do this.

6. The best setting for your bike will be somewhere between these two settings. The FM says to use the leanest setting [most screwed in] consistent with a good idle quality. Some guys say to go between the two settings.

It should be between 1/2 and 1,1/2 turns out from gently seated. If it is not within this range you should change the slow jet.

EDIT: I follow the advice from the old HotXL mag article - set it between 1/2 and 1,1/4 turns out.

7. You may have to adjust the idle speed.

8. Make sure that the spark plugs are clean, then ride the bike around your neighborhood for 10 minutes. Keep it under about 15 MPH so that you are on the "idle port", not the "idle transfer ports", the "mid range port", or the "main jet" [see carb diagrams in FM]. Hopefully the plugs will come out a nice medium gray or tan color. If they are too dark you can screw it in another 1/4 turn; too light screw it out 1/4 turn, and try the ride again.

9. If they are really light or really dark the problem may not be with the pilot screw setting. For example, too light might mean an intake or exhaust leak, and too dark might mean the slow jet is too large [among other possibilities].

10. My experience with this process is that after making a change i have to clean the plugs and go for a good ride [say, a half hour or more] before i can trust that the new results are reliable.

 

Wow awesome mick! i appreciate the effort..

one problem.. i've got the Zenith Carb with adjustable main..(Sound right??..or aint that the main? it does have 2 adjustable screws, AND a throttle stop screw..)

BUT, i did you your basic procedure. just wanted to see If what i had done was right!

Yinz guys are awesome!

 

I put zenith carburetor adjustment into the Google search. This is one of many responses ...
http://www.jaimekop.com/CarbManual/index.html
If that is not the correct one you could just check others until you find the right one. There are instaructions on the internet for adjusting/tuning that carb.