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  #1  
Old 08-06-2008, 09:36 PM
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Default Keihin CVK 40 27492-96 Carb spit, spit, choke sputter

Have had this 92 ultra classic tour glide with Keihin CVK 40 27492-96 Carb for several years. Love the bike, never lets me down. But when cold or at some stop lights it spits back through the carb, a real pain in the butt. I was going to replace the carb with an S&S E or a Mikuni but neither would work with the cruse control which comes in nice on the long rides. So ordered a stage 1 upgrade from Johns Motor Cycle parts and the EZ-Just mixture screw. Put them in today and have to finish re installing the carb in the morning. The bike has the Screaming Eagle Ignition Mod, K&N breather and modified stock mufflers. When doing the install today I noticed that there was burnt/black area in the Upper slide chamber area (from the popping back). when I changed out the pilot jet it had a # 48 in it I replaced it with a #46 the Main jet was a 185 which I replaced with the new one of the same size. Any ideas or suggetions, I'm all ears ??
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Old 08-07-2008, 03:29 PM
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Hey Critter:
This month's American Rider has Joe Minton talking about his fix for the Keihin CV. I've done this on each of my rides over the years with great results. I particularly like the earlier CVs like the one you have as they are a bit reacher than the later ones regardless of the jets, needles, etc. I assume you did the air screw thing, you just need to do the '88 Sportster needle and you should be good to go. You want to check for air leaks as well. Good luck.
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Old 08-07-2008, 06:15 PM
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Started on it at 7:30 this morning it's now 7 PM I have worked on it all day. I have installed pilot jets from 45 to 50, I put in all the nice new parts even the mix ****. It does not run past idle. give it gas and it sputers out. Have adjusted that screw from one end of the spectrum to the other. I even put all the old parts back in and the same thing. checked for air leaks etc. The orginal owner had work doen to the carb when he installed the K&N breather and Screaming Eagle Ignition mod. Tomorrow I will go see about another carb this one has beat me down. Did 4 carbs on an old Honda GL 1000 last year and had no problem at all.
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Old 08-07-2008, 08:39 PM
ajayrk ajayrk is offline
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Check the slide diaphragm for a tear or pin hole. Remove the emulsion tube and check for blockage and be sure the little steel needle jet is in place at the top of the emulsion tube. And check that the o-ring and small brass washer are still in the well for the idle needle.
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Last edited by ajayrk; 08-07-2008 at 08:41 PM..
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Old 08-07-2008, 08:56 PM
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Quote:
Originally Posted by ajayrk View Post
Check the slide diaphragm for a tear or pin hole. Remove the emulsion tube and check for blockage and be sure the little steel needle jet is in place at the top of the emulsion tube. And check that the o-ring and small brass washer are still in the well for the idle needle.

the diaphram is the only thing I would have question about. it just did not feel like I expected. New emulison tube was installed and everything else checked out. Took it off and put it back on 6 times checking or change something today.

thanks
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Old 08-10-2008, 07:31 AM
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With the air cleaner off, bike running, watch the slide movement as you give it throttle. Slice should move all the way up at full throttle.
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Old 08-10-2008, 12:58 PM
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+1 on the diaphram. When you put the cap on try turning it back and forth until you feel it seat properly. The cap should be solid against the carb body. If your bike ran well and then started having problems recently I would also say +1 on the intake leak. I believe this is the number one problem with carb jetting and mileage. If your heads are not rotated correctly the intake seals will not line up properly and it will leak. Harley's tolerances for their alignment pins are terrible. I had a FLHS back in 91 that had a 1/4" pin and a 3/8" hole in the cylinder!!! I can't believe some of the things I see come out of the factory. One thing I check is the alignment of your air cleaner mounting spots on your heads. Take a straight edge and put it on one of the heads where you air cleaner bolts up. This is a machined spot and should be in line with the other head. On my 2002 FLTR the rear lines up with the front but the front is an 1/8" out to the rear. This causes a gap on the right side of the intake and the seals cannot make up for this much misalignment. I also have an old Ramm Jett solid intake manifold I use to confirm my theory and sure enough the gap is there. There is usually some slop in the alignment pins between the cases and the cylinder and cylinder to head. You can usually correct the problem by twisting the assembly around till it is aligned. If you can't then I would enlarge the hole in the cylinder or better yet, elongate the hole to allow rotation. I've done several intake seals for friends and myself and the ones that are aligned don't leak, all the others do or will soon. Another way to tell is to look at the gap between the two bolt flanges and the machined edges on the intake manifold. This gap should be constant all the way around. If it's more on one side than another then your head is not aligned properly. Sorry for the long rambling, this is just a pet peeve of mine. As a Machinist the tolerances the factory uses just drive me crazy!!
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Old 08-10-2008, 07:13 PM
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thanks for the info. I ended up going to the Harley shop 40 miles away and picking up one of those gold plated diaphragms/slide. I am sure it is gold cause of the cost. came home drilled out the off set hole as per instructions in the up grade kit. Cranked it last night after getting home from worked was almost back to where it was when I started the project. pulled it back off this evening replaced the jets with a 46 and 185 put it back in and is doing much better. got dark on me so Will do the finish up tomorrow. Also installed the e-z mix screw while doing the up grade so got it close tonight.
did a lot of research, was going to go with the S&S E or Mikuni but every thing points to the well tuned stock carb getting the better gas milage.
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Old 08-10-2008, 10:12 PM
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Drilling the hole out will give you quicker throttle response but if the slide rises too fast it can also cause the cough. One thing you could try is to get a spare needle jet. The stainless part that your needle goes into on top of the emultion tube that holds the main jet. Take a #32 drill and drill it out. This will open it up from .114" to .116". Replace your stock one with the drilled one and use the stock needle for starters. Start with a 45 slow speed jet and see if the cough goes away. You might even get away with a 42 jet in warmer temps or higher altitudes. This has given me good mileage and performance on several friends bikes and my own. This is basically what the sportster needle does for you. It's .001" smaller at the straight part of the needle. Drilling the needle jet richens any needle just enough to help. Since the stock needle is so lean it usually works pretty good. It's pretty cheap if you want to try it.
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Old 08-11-2008, 12:59 AM
kansasroadking kansasroadking is offline
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Quote:
Originally Posted by tootal View Post
Drilling the hole out will give you quicker throttle response but if the slide rises too fast it can also cause the cough. One thing you could try is to get a spare needle jet. The stainless part that your needle goes into on top of the emultion tube that holds the main jet. Take a #32 drill and drill it out. This will open it up from .114" to .116". Replace your stock one with the drilled one and use the stock needle for starters. Start with a 45 slow speed jet and see if the cough goes away. You might even get away with a 42 jet in warmer temps or higher altitudes. This has given me good mileage and performance on several friends bikes and my own. This is basically what the sportster needle does for you. It's .001" smaller at the straight part of the needle. Drilling the needle jet richens any needle just enough to help. Since the stock needle is so lean it usually works pretty good. It's pretty cheap if you want to try it.
do they sell larger needle jets?, I'm not very good with a drill....
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Old 08-11-2008, 12:59 AM
 
 
 
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2749296, carb, choke, cv, cvk, cvk40, davidson, diaphragm, diaphram, ezjust, harley, hd, keihin, mixture, run, screw


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