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*Twin Cam CV Carb Rejet Suggestions

Might try this as a quick test.

With the bike warmed up at operating temp, pull out the enricher. Then look at the exhaust and rev it a few times. If there is absolutely no black smoke when it picks up off idle, it might be safe to richen up the pilot jet .01 or .02
But honestly... I'd listen to Mr. Data on this one. He's a cv carb genius that most likely knows a ton more than i do about this. Also, what altitude do you normally ride at? If you're in colorado or something... Go with the 48
 
Mr. Data. the link in the main post of this thread takes you to a page with several jets. the answer i think i know is an obvious one that i would be wrong about if i assumed, so dont laugh too hard:) 96 dyna with keihin carb, screamin eagle pipes(not loud enough), and stock intake. im adding the v&h short shots and im assuming from what ive read that the intake needs to be stepped up a notch too, np so far. 190 stock high speed jet, 2 #4 washers, and then theres the #46 idle jet.

first, the idle jet is referred to as a pilot jet aswell, correct?

secondly, is #46 the same as 46mm, part number 400-861 on the jp link you provided?

thirdililly..:rofl..ok, im over it... ive read through the posts and did a little searching elsewhere, but alas, here i am. thanks for overloading the net up with what ya know.
 
secondly, is #46 the same as 46mm, part number 400-861 on the jp link you provided?

i answered this myself, except i want to verify the part number is the correct one you meant anyways. #100 equals 1mm, thus #46 is a .46mm, per info on a site i found. thanks again
 
Question about the idle mixture? In addition to the screw, spring, and washer, should there also be a rubber 'O' ring? I've seen some kits online that have the 'O' ring - others that don't. Does the 'O' ring come with the stock carb?

Question about Ebay carbs. There's a dealer selling carbs that list as "Carb/Carburetor CV Harley Davidson 40MM Performance NEW" but they do not have the HD logo or name cast into the body. I asked and he replied that they were aftermarket items. Steer clear of these?
 
Howdy.

I'm new here and am having some probs with my carb and am getting some great info from this forum. Quick question..... this is copied from the instructions above about how to set the air screw.

"The SLOW JET and AIR SCREW are most effective in this range When you want a richer mixture use a larger SLOW JET or turn the AIR SCREW in. The opposite holds true for a leaner mixture"

Question is, isn't turning the air screw in making the mixture leaner??? Out makes it richer??? Thats what I've read every where else.
Thanks.
 
Howdy.

I'm new here and am having some probs with my carb and am getting some great info from this forum. Quick question..... this is copied from the instructions above about how to set the air screw.

"The SLOW JET and AIR SCREW are most effective in this range When you want a richer mixture use a larger SLOW JET or turn the AIR SCREW in. The opposite holds true for a leaner mixture"

Question is, isn't turning the air screw in making the mixture leaner??? Out makes it richer??? Thats what I've read every where else.
Thanks.

Should have read...

"The SLOW JET and AIR SCREW are most effective in this range When you want a richer mixture use a larger SLOW JET or turn the AIR SCREW out . The opposite holds true for a leaner mixture"

You are correct in what you posted.
 
Hey, it's me again. Guess I should give a little background on why I'm messing with the carb in the first place. Hope I don't bore y'all with the details here, but better tmi than not enough.

Rode an '82 Anniversary edition Sporty for 25 yrs. 3 yrs. ago decided to upgrade. Got a 2000 Heritage Softail with 14K miles on it from the original owner. Some rich guy, didn't know a thing about bikes, so had the dealer do all the work on it. Bike is immaculate. Only thing he did to it other than routine maintenance was put on a high flow air filter and V&H 2 into 1 pipes. He said the dealer rejetted the carb with the new pipes, but he didn't know what size they were. It ran great, so who cares what size they were. Not too long after I bought it, I put on V&H longshots. Didn't like the looks or sound of the 2 into 1. The long shots looked and sounded much better and it didn't affect performance at all.
Now for the problem..... about a month ago, (23K miles) I changed my oil, filter, primary gasket and fluid, new battery, and new plugs. The old plugs were in there since I've had it, but they still looked real good. Put in new ones anyway. Rode it about 300 miles. Rode great. Shifting was a little quieter too. Two weeks ago I went for a long ride and about 30 miles into it, it popped once thru the carb. Then ran fine for about 10 more miles and it popped again. Every 10 miles it would make one pop thru the carb. Came home about 150 miles later and thought one of the new plugs might be fouled. Took them out and they looked new still, but went back to the old plugs just to see if that made a dif. Rode it again, and same thing. Every 10 miles one pop, but it ran great between pops. Ok, might be something stuck in the carb. Bought a rebuild kit from the dealer last Friday. Saturday I rebuilt it. Opened up the carb and it looked real clean. Changed gaskets, O-rings anyway. Blew out holes with my compressor. Jets are 48 slow and 190 main. I see Mr. Data says 48 might be too big for a stock motor, but it ran great for 3 years prior. Just ordered a 46 and one of those EZ just air mixture screws, but haven't got them yet so I put it back together the way it was. The plug had already been drilled out and it looked like they went to far and buggered up the head of the screw. I took it out and used my hack saw to make a groove that I could get my screwdriver into for adjustments. Put on new O-ring, washer, and original spring. Backed it out 2 turns from lightly seated. Put it back on the bike and it started right up after the carb filled up with gas. I only use 93 octane gas. Let it warm up and adjusted the air screw. Turned it about 1 full turn in and then two full turns out and didn't notice and difference in the motor sound. Set it back to 2 turns out and went for a ride. 1st - 4th gear sounded great. Hit the highway at about 55-60 mph, winding it out a little bit in 4th gear. Popped it in 5th gear, gave it the gas and it started popping thru the carb again, only this time instead of one pop every 10 miles, it's popping about 10 times every mile. Didn't go too far like that. Came home. Why would it pop in 5th gear at 3-4K rpm, but not in 1st-4th gear at 3-4K rpm??? I don't have a tach on the bike, so I'm just guessing at rpm's here. Any ideas why it's popping worse??? The diaphram isn't pinched (made sure of that before I put the top cover on). It's very clean. No leaks. Should I swap the 48 jet to the 46 when I get it, even though it ran great with the 48 for 3 yrs. Should I put the two #4 washers under the needle??? Should I drill out the slide like I've read about??? Some say it's better to, some say don't do it. Is the 190 main jet too big??? If I could just get it running like it did two weeks ago, I'd be happy again. I know this was a long post and you're probably tired of reading it by now, if you got this far, but like I said, I wanted to give a detailed account of what was going on. I know how hard it can be to attempt to diagnose something online with only a little bit of info.
Any help, advice, suggestions, etc. would be greatly appreciated. :bigsmiley12:
 
:small3d031:I've never seen a detailed account like that! Good work!

This is the easiest way to reply to you.

Turned it about 1 full turn in and then two full turns out and didn't notice and difference in the motor sound.
Probably because of the oversize jet, you aren't getting a mixture adjustment now.

Set it back to 2 turns out and went for a ride. 1st - 4th gear sounded great. Hit the highway at about 55-60 mph, winding it out a little bit in 4th gear. Popped it in 5th gear, gave it the gas and it started popping thru the carb again, only this time instead of one pop every 10 miles, it's popping about 10 times every mile.
Still say it's too much fuel and you did change the idle mixture adjustment. Hard to diagnose with a #48 jet in there.

Didn't go too far like that. Came home. Why would it pop in 5th gear at 3-4K rpm, but not in 1st-4th gear at 3-4K rpm??? I don't have a tach on the bike, so I'm just guessing at rpm's here. Any ideas why it's popping worse??? The diaphram isn't pinched (made sure of that before I put the top cover on). It's very clean. No leaks. Should I swap the 48 jet to the 46 when I get it, even though it ran great with the 48 for 3 yrs.
Yes! swap it for the #46

Should I put the two #4 washers under the needle???
Yes, with the proper jetting this will bring in the fuel circuits a bit earlier for better performance.

Should I drill out the slide like I've read about??? Some say it's better to, some say don't do it. Is the 190 main jet too big???
190 is WAY too big for what you have there. DON"T drill the slide, under cold conditions and low RPM you can get a big bog drilling the slide.
 
Thank you Mr. Mr. Data. You're the man!!! I think it's awesome that you take the time to help out us "less intelligent" riders. If you're ever in Dallas, I'll buy you a beer or two :bigsmiley12:
One more question.... you say the 190 is too big. What should I go with? 180? 185? Do I have to keep changing them til it's right? Like I said, it ran great since I had it, up until two weeks ago, with the 48 and 190. Or was I not realizing the full potential? OK, so that was more than one question. :D
 
180 or 185 should do it depending on your tune and options.

Try it this way to determine main jet size, it's all in the post at the top. Do this after setting up everything else.
Quick and easy way of testing the main jet size.

Run the bike through the gears into third gear and run third up to 60-70 MPH full throttle, then chop the throttle about 1/8 to 1/4 back and see if the bike either surges ahead or stumbles then recovers.


If it surges ahead, your jetting is lean

If it stumbles and recovers , your jetting is rich
If it makes no difference, you're pretty close.


This will give you an idea of the adjustable jet needles and how to richen up the mixture.

Using the stock jet needle, you shim it up with 2 - #4 washers under the head to raise it up in the slide. The stock needle does not have the grooves for adjustment.
 
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