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To Re-Jet or Not to Re-Jet.....?

4K views 13 replies 6 participants last post by  matt21080 
#1 ·
Just picked up a set of V & H Classic II's (V19367) for my '04 1500E Classic. This setup eliminates the "Goat's Bladder" resonator....Just would like to know if a Re-Jet kit (V21137) will be necessary? The intake setup is stock...

Thanks,
Steve
 
#2 ·
Probably not necessary, but a good idea. If you notice popping through the carb is a sure indicater that you are really lean, then you should jet to prevent burning the piston, rings and valves. Most all vehicles are set lean from the factory to begin with. Even totally stock, there are usually performance benefits to jetting.
 
#3 ·
Odin, we share the same situation. I just recently purchased a 2004 classic with a bad engine. (see my post in this section,"bought a basket case"). Well I have got the new engine installed and since the bike came with V&H Longshots, I installed them. The bike starts and idles perfect, but when I try to give it some gas, it stalls. If I feather the throttle I can get past the stalling and it picks up and runs good.
On a previous 99, 1500 classic I had a very similar situation, it also had V&H pro pipe, 2 into 1, with a hypercharger. The only way I finally got the bike to perform right was thru trial and error of changing jets. I settled on a #55 pilot and a #170 primary. Not the best combination if you are looking for milage, but that bike sure runs great. I will be ordering the same combination for the current 2004.
 
#5 · (Edited)
Just some experience with doodling around with these carbs: Take it in small steps- a small modification can make a big difference. If you're running a stock air cleaner, you can probably leave the pilot jet alone and just turn your fuel/air mix screw out to 2-1/2 turns. Stock main jet is a 138; I'd not go over 145 to start with. I'd also drill the slide out to a 1/8" hole. This will improve throttle response and help end that stumble or hesitation when throttling up. If you get a tapered needle with the kit, I'd start with the c-clip three rings down from the top.

Even with a Baron's Big Air and Cobra Lowboy Shotgun pipes, I only am running a #150 main jet and a #48 pilot (45 is stock). I get a nice balance between performance and mileage. I can run 70 all day and still get 39-42 MPG running regular 87 octane gas. It's a little lean at the very top end, but I rarely ever run it there.
 
#6 ·
Don't drill the slide. Thats outdated advise there. If you don't believe me you can call dynojet or whoever makes your jet kit. It may say to drill in the instructions but thats because they never bothered to reprint them for the older kits. My 1500 had a thing with the throttle where it would have no power then all of a sudden take off quick. Turned out the slide was drilled to 1/8 so the slide would lift too quickly. I replaced the slide with a new non-drilled slide and it has a smooth transition now. If you want to help with throttle response and help get rid of flat spot off idle maybe try one of these http://www.cv-performance.com/cvp-slide-spring/
 
#8 · (Edited)
Where did you ever hear that about the slide lifting too quickly? Sounds like something other than the slide if your bike suddenly lurched after throttle. Mine's drilled to 5/32, or slightly larger than 1/8, and it's never run better. No stumbling, no lurching. Having said that, if he's keeping the stock air system and not upgrading to a high-flow air filter, there's probably no advantage to drilling it out as these stock air systems are quite restrictive as they are. On the other hand, I have a Baron's Big Air with a high flow filter mounted right to the carb.

If you get on the throttle quickly, the slide lifts to allow the bike to take a big gulp of air, but if it's slow to respond because of air pressure behind it, there is a second where it is fuel starved, causing the hesitation. A bigger hole allows the slide to displace the air more quickly and allow fuel into the intake a little faster, matching the sudden increase in air volume. That's all it does. It doesn't increase horsepower or anything else, just eliminates the stumble or cough at takeoff without having to set the carb too rich. If your bike suddenly lurched, I'd want to see where your c-clips are on the needle and the size of your pilot jet. Some guys like to increase the overall amount of fuel that gets delivered to the intake to over come this issue. Thus the huge jets, when the problem is a lack of fuel at a specific time in a specific place which is easily fixed without necessarily pouring more gas through the carb.

Whatever works for you, though. Some guys insist on 170 main jets and 56 pilots and I've never seen a need for them unless you like to burn a lot of gas needlessly and like getting 33 mpg. :D
 
#9 · (Edited)
You can find alot of links of real carb tuners advising against drilling the slide.
http://carbjetkits.com/drilling-carb-slide.html <-notice he says it can cause a hesitation at the bottom. http://www.cv-performance.com/harley...tuning-issues/ <-scroll down to 6 and ken talks about over drilling the slide. If you do searches on the harley forums about drilling the slide they all advise against it. You know harley uses the same cv40 carb as ours except without a carb warmer. And these guys tinker even more than us with carb settings and dyno tunes etc... I have heard it from some vulcan 1500 owners as well, It wont let me post a link from the archive at vroc.com but here is the quote :The 1500 reacts to the slide being drilled in a very negative way in my
opinion. The throttle loses it's ability to *feather* the gas at really
slow speed situations like slow turns in a parking lot. It feels more like
an on/off switch than a throttle just above idle and can really be quite
disconcerting if you have the bike leaned over doing a slow turn and you try
to feather the throttle and it just shuts off and then you react by giving
it more throttle and it *jumps* out from under you. It has taken me a while
to get used to it and I would not recommend it. <-thats a post from 2003
 
#11 · (Edited)
You can find alot of links of real carb tuners advising against drilling the slide.
http://carbjetkits.com/drilling-carb-slide.html <-notice he says it can cause a hesitation at the bottom. http://www.cv-performance.com/harley-cv-carburetor-tuning-issues/ <-scroll down to 6 and ken talks about over drilling the slide. If you do searches on the harley forums about drilling the slide they all advise against it. You know harley uses the same cv40 carb as ours except without a carb warmer. And these guys tinker even more than us with carb settings and dyno tunes etc... I have heard it from some vulcan 1500 owners as well, It wont let me post a link from the archive at vroc.com but here is the quote :The 1500 reacts to the slide being drilled in a very negative way in my
opinion. The throttle loses it's ability to *feather* the gas at really
slow speed situations like slow turns in a parking lot. It feels more like
an on/off switch than a throttle just above idle and can really be quite
disconcerting if you have the bike leaned over doing a slow turn and you try
to feather the throttle and it just shuts off and then you react by giving
it more throttle and it *jumps* out from under you. It has taken me a while
to get used to it and I would not recommend it. <-thats a post from 2003
Well, mine's been drilled out for 8 years and 41k miles and I've never experienced anything like the hesitation and jumping that you posted here. I still suspect the problem lies elsewhere in the carb if it's doing that. As for "real" carb tuners, the guy who worked on my bike has been a certified mechanic for Yamaha, Honda, and Kaw since 1983 and now works on racing bikes, so I'd say his opinion counts for something.

The point is, not all "real" carb tuners agree. Slow speed has never been a problem with my bike, and I've driven through LA and San Diego freeways at rush hour with it, it starts out smooth as silk. Oh well. Whatever works for ya, but if I had another one I'd drill it out too. :D
 
#14 · (Edited)
a 165 main was perfect on mine with the thunder mfg intake,and long shots with quiet baffles. This carb has the dynojet needle adjusted probably similar to what the stock needle would be. It leans out for cruising mpg and then the 165 gives max power when needed. I get over 40mpg if I don't get on it too hard. You can see when he gave it throttle at 2.5 rpm the accelerator pump compensates for any slide delay.http://i1190.photobucket.com/albums/z448/matt1357/GEDC2004_zps619c266a.jpg
 
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