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  #11  
Old 10th August 2010
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Beautiful bike, man!

Looks like it came right off the showroom floor, only better with the extra chrome. Love those 18" rear wheels. You should post it in the "Post a pic of your AMF Sporty" thread.

http://www.xlforum.net/vbportal/foru...d.php?t=666910
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  #12  
Old 10th August 2010
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Sounds like you are confusing the fast idle stuff with the accelerator pump.
The accelerator pump is a band aid and a starting aid.
For normal operation the accell pump is not really needed.
It only comes into play for rapid changes in throttle to keep the motor from stumbling IN GEAR.
If you are trying to get it to fix a stumble from a too slow idle to WOT as fast as you can grab a handful, you will be unsuccessful.
The low speed jet must be correctly sized and the idle mixture correctly adjusted prior to any fiddling with the accell pump. I would look for problems there first, including vacuum leaks, float level, and ignition areas.
I have heard that some of the Kehin carbs need very specialized mods to work properly, be prepared to try a different carb.
What jets are in it now?
Which idle mix screw does it have, long skinny tip (late), or short fat (early)?
And how many turns is idle mix screw set at? (for best idle at 950 rpm HOT)
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  #13  
Old 10th August 2010
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i just got these pics downloaded from the camera this morning. I will put them over to the other thread later on.

Now, a little bit about what was done. Most everything was done at home. The only work done by an outside shop was the crank bearing sizing, bore (.050), and valves/guides all of which was done through a local Indi shop.

I relaced my own wheels trued and balanced, stripped and polished the aluminum parts, put inserts into all of the engine case threads, stripped and painted the frame, tank and fenders, all new stainless bolts, new bearings and bushings throughout.

I tried to stay as stock as possible, but decided to use the Showa 35mm front end that was on it. A lot of my parts are NOS OEM including the seat!

This is my first Harley and a recreation of what I tried to buy in '72. I was looking at the end of the model year and couldn't find one to buy in 3 states.

This forum has given a wealth of info for a first time builder... so "Hat's Off to all who have contributed to the site".
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  #14  
Old 10th August 2010
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Thanks Ryder Rick, for the input. You're right about chasing my tail on this. This carb was on the bike when I bought it last year, and I "assumed" that it would have been close enough to run decent. Guess What!

without actually being able to see the two different needle screws, I am guessing that I have the skinny one. Right now it has a #70 slow jet and a #155 for the main. I know they are wrong (by the way it runs). I posted the makings earlier for Mick, to see if we can identify which model year I have here. From there I figure I'll have some idea of where to start for sizing the jets.

This bike was a cobbled up mess from the git go, so having a miss-match here is no surprise. I'm chasing several different issues and gone through all the rest of the possibilities.... intake/exhaust leaks, pushrod adjustments, timing, etc. It has been starting good, but running like crap..... spitting sputtering farting out the exhaust and backfiring through the carb, falling down on rapid acceleration, idling too fast, running hot, and waking up the neighbors.

The Kiehin carbs aren't the best in the world, but they will do a good job if they are set up correctly. that's where I am now, and why I'm asking for advice.... so keep it coming!!!!!

Right now the carb is off the bike, until I can figure out what range of jets to start with. I think I have all the other stuff sorted out, but won't be able to verify until I change the jetting. The FM doesn't really give a lot of information to figure out a lot of this stuff, and since it is no way a stock setup, makes it difficult to get from A to B without a bunch of head scratch'n.

Again, thanks for any input!
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  #15  
Old 10th August 2010
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That mixture screw does not have a large range of adjustment, I believe you need to increase the low speed jet size.
After you have eliminated all other contributing factors.
The symptoms you describe sound like the low speed jet is lean.
Try the 88 slow jet and see what happens.

A fast idle can be caused by the idle not being set when the bike is HOT.
A fast idle can also be caused by an advance mechanism that is not functioning correctly.
Running hot can be caused by vacuum leaks or bad ignition events.
Backfiring can be caused by bad plugs.
Use standard OEM style plugs and buy a box of them until you get it sorted out, if you have electronic ign you must use resistor plugs. Start with a small gap, .025 and increase gap as you are able, electronic can go as high as .045.
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  #16  
Old 10th August 2010
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Thanks Rick,

Of the possibilities you listed (besides the jet size) two things stand out as possibilities. I just changed out the mechanical advance assembly and made sure it was lubed and smooth. The plugs are new Autolite #85 with a gap of .042". I have a new coil and new plug wires, along with the Powerhouse Dual Fire #17554 electronic ignition.

I'll try re-gaping the plugs, but I am wondering about the vac leaks? I have really worked on sealing up the head connections to the exhaust headers and the intake manifold. The gaskets between the carb and the "Y" manifold are new and the surfaces are flat and true. Where else would it possibly be leaking vaccum? I've used the propane bottle method and spraying WD-40 all around with no noticeable change.

I am pretty well convinced that the main problem is the low jet size, with maybe some secondary issues that will be more noticeable after I get the jets worked out. I've now tried the #70 and the #65 jets, which are in the stock range that Mick posted earlier, so the #88 may be too rich. At least that will hopefully show enough of a difference that I can narrow it down.

I'll have to wait 'till tonight after it cools down... this heat is killing me (heat index is 110 - 115). I'll let you know. Thanks
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  #17  
Old 11th August 2010
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I re-gaped the plugs to .038 and put the #88 slow jet in..... PROBLEMS SOLVED! well almost. I still need to do some work on the choke cam assembly and set the choke idle, but the bike runs 100% better now. I have the idle set to right at 1000 RPM (less if I force the choke cam). The mixture screw is about 1 1/3 turns out and it idles smooth with good throttle response.

I took it for a cruise around the neighborhood without any problems, except for getting used to the left side brake. I'll pay attention to the WOT response when I get a little more used to riding, so may still have an issue with the main jet, but we'll wait and see.

Thanks again guys for the help getting me on track.
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  #18  
Old 14th August 2010
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A friend sent the following information regarding things that he has done to the Keihin carbs and had success with them over the years, so I thought I would share it with the forum:

JIM

I WORKED ON THE KEIHN CARBS BACK IN THE 70’S WHEN THEY WERE NEW. THE GUY I WORKED FOR WAS A TOP RACER & HD DEALER AT THE TIME. EVERY BIKE HAD TO BE TUNED PERFECT. I HAVE ONE OF THESE CARBS ON MY 1971 FLH AND THIS IS WHAT WE DID TO MAKE THEM WORK.

1.- YOU ONLY NEED TO SHORTEN THE ACCELATOR PUMP ROD IF WHILE RUNNING IT IS SPITTING FUEL OUT OF THE PUMP JET. IF IT IS SPITTING YOU WILL BE ABLE TO SEE IT DOING SO. THIS WAS A FIX FROM THE FACTORY.

2. – SOMETIME THE BLACK PLUG IN THE LOW SPEED JET , IS TO LONG AND SHOULD BE TRIMED OFF TO ALLOW MORE FUEL IN THE LOW SPEED SIDE. TRIM OFF AS MUCH AS NEEDED TO STILL HOLD IT IN WITH OUT FALLING OUT ABOUT 1/8”. THIS WAS ALSO A FACTORY FIX.

3.- FOR THE COUGHING AND SPITTING WHAT I DID WAS DRILLED THE LOW SPEED JET OUT TO 1/32”(.031) THE COUGHING AND SPITTING IS A COMBINATION OF THINGS BUT THIS SEEMED TO CURE IT FOR ME, (ON MY BIKE I HAD THE DRILLED OUT LOW SPEED JET IN RAN GREAT, I BOUGHT THE BIGGEST LOW SPEED JET AVAILABLE PUT IT IN AND IT COUGHED AND SNEEZED, CHANGED IT BACK AND THE PROBLEM WAS SOLVED), ANOTHER THING TO LOOK AT BE SURE YOUR AIR CLEANER IS FREE FLOWING IN OTHER WORDS MAKE SURE ITS GETTING PLENTY OF AIR. IF YOU ARE RUNNING THE 72 AIR CLEANER BACKING PLATE THE OUTSIDE OF IT SHOULD FIT TO THE SIZE OF THE AIR CLEANER. THE 77 AND LATER BACKING PLATES HAD AN AIR HORN AND THEY WEREN’T GETTING ENOUGH AIR.

4. – I ATTACHED A PIC OF AN ADJUSTABLE MAIN JET AVAILABLE FROM J & P CYCLES, THESE WORK GREAT AND YOU DON’T HAVE TO FOOL AROUND JET GUESSING WEATHER YOU HAVE THE RIGHT SIZE MAIN JET IN OR NOT. SIMPLE TO ADJUST WIND IT UP TO ABOUT 65 MPH AND TURN IT IN UNTIL IT MISSES AND BACK IT OUT ABOUT ONE FULL TURN, THEY WORK GREAT.

5.- ANOTHER THING THAT I HAVE ON MINE IS HIGH FLOW ACCELATOR PUMP ALSO AVAILABLE FROM J & P CYCLES THESE WERE ALSO A GREAT CURE FOR THIS CARB ALL AROUND.

6.- THE FIRST SERIES OF THESE CARBS WORKED THE BEST AND HAD MORE ADJUSTMENT TO THEM (THE LATE 76 TO EARLY 78’S). IF I REMEMBER RIGHT THERE WAS NO CHOKE CAM ON THEM, & THEY HAD A DEEPER FROST PLUG IN THE TOP AND A WIDER RANGED AIR SCREW IN THEM. ANOTHER FACTORY FIX WAS TO SEAL THE FROST PLUG IN THE TOP WITH SILICONE TO BE SURE THEY WEREN’T LEAKING. EVERYBODY THINKS THAT THESE CARBS WERE JUNK AND STILL DO, EVEN SOME OF THE TOP HD MECHANIC I KNOW STILL THINK THAT, BUT WE DID THE ABOVE FIXES TO 100’S OF XL’S & FX’S & FLS AND THEY ALL WORKED AS GOOD AS AN S & S OR ANY AFTERMARKET CARB DID. WE JUST NEVER TOLD ANYBODY WHAT WE DID TO THEM.

7.- ON YOUR IGNITION TIMING RUNNING IT SLIGHTLTY ADVANCED IS GOOD, WITH POINTS WE USED TO RUN THEM ADVANCED UP TO 8 TO 10 DEGREES SO THAT WHEN THE POINTS WORE THEY WOULD STILL BE WITH IN AN ACCEPTABLE RUNNING TIME. WITH A ELECTRONIC IGNITION THE TIMING NEVER CHANGES SO 2 TO 4 DEGREES ADVANCED IS ABOUT RIGHT. AND TIME IT WITH A LIGHT AND RUN THE MOTOR UP TO FULL ADVANCE (ABOUT 2500 RPM’S). I DID THE SAME THING WITH MY BIKE AND CHANGED TO AN STOCK ELECTRONIC IGNITION, FROM AN 89 WITH A SCREAMING EAGLE MODULE, WORKS GREAT.

8.- AND FINALY THE GAS TODAY IS SHIT, I SAY TO RUN SHELL 93 OCTANE IF YOU CAN THAT SEEMS TO BE THE BEST RUNNING IN MY BIKE. ONCE YOU GET IT TUNED IN TRY TO GET SOME STOCK CAR FUEL, WE HAVE IT HERE “CAM 2”110 OCTANE LEADED (4 GRAMS OF LEAD PER GALLON) IT’S EXPENSIVE ABOUT $6.00 PER GALLON BUT WHO CARES WHEN YOUR ONLY BUYING A SMALL AMOUNT, WHEN YOUR BIKE WAS NEW IT WAS MADE FOR RUNNING LEADED GAS. THE GAS STATION I GET THIS FROM DIDN’T WANT TO PUMP DIRECTLY IN MY BIKE AT FIRST FROM THE PUMP AT FIRST BECAUSE THEY SAID THAT IT WAS ILLEAGLE BUT I TOLD THEM THE YEAR OF THE BIKE AND WAS LEADED WHEN IT WAS NEW AND THEY SAID THAT IT WAS OK TO DO THAT. YOU WILL BE VERY HAPPY WITH THE WAY IT RUNS ON THIS GAS.

THE ONLY OTHER THING YOU MIGHT WANT TO DO IS TO THE MUFFLERS IS MAKE THEM STRAIGHT THROUGH, WHICH MAKES THEM A LITTLE LOUDER BUT MORE FREE FLOWING, JUST KNOCK OUT THE BAFFLE PLATES. YOU STILL RETAIN THE BACK PRESSURE NEEDED BUT YOUR NOT CHOKING OFF THE MOTOR WITH THE BAFFLES. YOU WANT THE RIGHT AMOUNT OF GAS IN AND THEN GET IT OUT AS QUICK AS POSSIBLE, AND YOU CAN’T DO THAT WITH RESTRICTIVE FACTORY MUFFLERS.

NOW GO OUT AND TRY THIS AND LET ME KNOW WHAT YOU THINK AND HOW IT RUNS. ALL OF THIS COMBINATION OF THINGS DO WORK. HOPE THIS HELPS AND ANSWERS A LOT OF YOUR QUESTIONS, THAT I READ ON THE XL FORUM. THE ATTACHMENTS ARE FROM THE J & P CYCLE CATALOG.

RICK
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  #19  
Old 15th August 2010
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Quote:
Originally Posted by oldnavy View Post
A friend sent the following information regarding things that he has done to the Keihin carbs and had success with them over the years, so I thought I would share it with the forum: ...
Thank you for posting this. I copied the post into a new thread and linked it into the Stickys. Thanks again.
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