| Author | Message | ||
     Nocompromise |
I'm still struggling with jetting this Mikuni. I now have a Dyna 2000 with the least aggressive curve, and much richer jetting on the needle and main. If I quickly open the throttle from below 3000, it really bogs and stutters a lot. I don't know if my expectations are too high, but I don't think so. If I roll it on smoothly, then it does 'ok'. Do I need to richen the needle even more? That's what I'm going to try tomorrow, but my hopes are not very high. It almost seems like a VOES problem, but I double checked it was plugged in. I will have to look in the manual to see how to make sure it is operating. So, what happens if you quickly open your throttle at 2200-2800 rpms? | ||
| Bad_karma |
Kevin You should be able to whack the throttle open with better than stock response. Of course 2000rpm in fifth, whack the throttle don't expect more that the motor can give. But in first it should just go. Without reading the plugs or see the bike run I can't say for sure. But of three Mukinis I have they come jetted pretty close. I would go back to the original jetting and start again. Also visit their website if you don't already have their tuning pamphlet. Joe | ||
| Firemanjim |
What do your plugs look like? Now that you have your timing curve and timing set so you don't ping you might actually be too rich--- make sure your accell pump is adjusted properly--IIRC that was in tuning guide. | ||
| Ratbuell |
My bikes rotate skyward, at least in lower gears  Of course, I run stock carbs, 45/190 jetting, and factory-spec Thunderstorm engines. | ||
| Tripp |
to the moon alice to the moon!!! | ||
| Nocompromise |
Thanks for the answers guys. I forgot to mention that it only happens in 4th and 5th. Is this normal behavior in those gears? | ||
| Firemanjim |
Well,RPM should be above 3000 with T-stormed motor to get into start of power band,esp in highest gears as that is biggest load on engine.But still should be smoother than you are making it sound. But remember,Mikuni is not a CV carb so if you wack it open all the way you all of a sudden have a BIG opening for air/fuel to accelerate into. | ||
| Nocompromise |
That's what I figured Jim, so i just don't know if my expectations are unrealistic. If you have a little time maybe you could take it for a test ride and see what you think. I don't know what your schedule is like, but maybe today or tomorrow afternoon/evening? I'm going riding tomorrow out to Skaggs, but I'd like to figure it out if at all possible before my trackday on Sat. | ||
| Captainkirk |
It goes like hell! And that's with the Mikuni HSR42. Make sure your VOES is working, not just plugged in. Also, what exhaust are you running? | ||
| Nocompromise |
Kirk, I also suspected the VOES, so I just got done checking it. Like almost everything else on this bike, it was very easy. Plus, I got to use the mulitmeter for the first time in quite a while. In addition to checking good on the multimeter at the appropriate vacuum (5-6 psi), you can actually hear the VOES switch on and off. I guess something could be bad in the wiring harness, but I'm not sure how I would go about checking that. I'm running a Force, which are not supposed to be very good down low. But, I wouldn't think it should be THIS bad. If it's even at 2900 in 4th or 5th I have to roll it on at a moderate rate or it will give me some hesitation. Even if it was too rich, I don't think it would exhibit these symptoms. My logic is that (as Jim writes) this is a situation that is creating a very BIG opening for air all of a sudden, so the demand for fuel is very high all of a sudden. This is a situation where it would seem to be very hard to be too rich. Plus I've read that, in general, hesitation when under demand means too lean and hesitation when not under demand (sudden roll off) means too rich. Since this is a huge demand situation, I'm thinking it's too lean or the VOES isn't operating properly (or the Force is killing my bottom end with no back pressure). These are all just the ramblings of a novice. I guess I'll try richening the needle one last time. If that still doesn't work, then I know it must be something else (96 needle currently in mid position - I'll move it to full rich). I'm hoping to have a replacement for the Force sometime in the not-too-distant future, so perhaps that will alleviate the problem. Thanks for the help and inputs!! (Message edited by nocompromise on December 21, 2007) | ||
| Bad_karma |
Kevin If I remember correctly my accelerator pumps where adjusted with a large gap. I closed that initial gap down. Joe | ||
| Nocompromise |
Joe, Thanks for the idea. I don't remember where mine were initially, but I closed it down to Mikuni's recommended 2mm (via the Tuning Guide). Basically, it actuates almost as soon as the throttle is opened (2mm isn't much). One small thing that happened when I was changing the needle clip position - I've changed the needle at least 4 or 5 times (needle clip position or the needle itself), so it's pretty routine. Tonight when I did it, the clip kept getting hung up on the metal assembly that goes up and down when you open or close the throttle. The clearance was definitely tighter than before, and I'm not sure why. It made it a real pain in the ass to get it out.  Anyway, needle is now a 96 at full rich. Judging from a couple other people with similar setups, there's no way that should be too lean. So, if this doesn't fix it (I'm not optimistic based on my utter failure so far), then I'm about stumped. Is there any way to check at the ignition module as to whether the VOES is working? | ||
| Bad_karma |
Kevin Fourth and fifth gears below 3000 to 3500 don't expect anything like first and second. My 96 S1 in the stock form would spit back thru the carb. if I whacked it open. I just learned to be smoother with the throttle(leaned over in a turn, a stuble is a real eye opener). Can't help you with voes question neither of my bikes have them. I want to say that i'm running a 97? (Middle needle)with the clip in the second groove down from top. Do you still have the washer that goes under needle's E-clip? It's a learning curve just takes time and very good note taking skills. Oh I usually only change one thing at a time. Hope I'm not insulting but for me I have to keep it simple when I due carbs. Holley taught me that. Probly one of the most rewarding things you can do to your bike if not a close second to suspension tuning. Good luck joe (Message edited by bad_karma on December 21, 2007) | ||
| Nocompromise |
Lol Joe, no I'm not insulted! I'm an amateur, so any tips are much appreciated. I do still have the washer under the E-clip. My bike is a 97 S1 and it has a VOES. I know I shouldn't expect that much, but with the amount of stuff this bike has done to it I thought it wouldn't be so gutless. Thanks again and have a good one! -Kevin | ||
| Aesquire |
I've got a 2001 M2L with the stock carb rejetted to my tastes, ( you have the Mikuni, so 45 idle 2 1/2 turns .030 needle shim 195 main means diddle, I just throw that in for the cv40 carb guys ) and a Wileyco slip on. When I was riding home at midnight because of work, I wanted to quiet it down & threw the stock muffler back on & the 200 mainjet. Back to stock, more or less, right? Suddenly I was getting a bog at large throttle openings. I ask a bud who ran his own shop for years his opinion, after a quick test ride, "too lean" was the diagnosis. Down the road to the H-D shop in Hornell NY. I ask for 205 main jet. I get a cardboard box with ALL the jets they have. Mikuni, CV, snowmobile... My buddy tells the manager HE'd make the mechanics sort them. I find a 205, we toss it in, I take off, whack the throttle, it sounds like a water hammer in bad plumbing, & has the power of a broken chain saw. Back to the 195, happy trails. In other words, It might NOT be lean. | ||
| Nocompromise |
Jim and Patrick - you each get a cookie. It was Rich, not lean. I tried going full rich on the needle (from mid) and it ran even worse. Before I left for my ride (I'll try to post a couple pics later), I moved it to full lean (since I knew mid wasn't quite right). It ran MUCH better. It pinged a little here and there, so I'm hoping the second notch (in between full lean and mid) will be the magic one. Thanks for all the help fellas!! I've got a tale of horror that I will try to type up later - I have to prep my bike for an Infineon track day tomorrow.  (Message edited by nocompromise on December 21, 2007) | ||
| Bob_thompson |
My experience was exactly the same as Pats (Aesquires)with a stock 2002 M2 and CV carb. Pipe, straight thru muffler and K&N oval air cleaner. It kept doing what you both were encountering, stumbling a lot. Kept riching it up right to 205 main. worse. Went back to 195 main, 45 pilot jet and .060 shim washers under the stock clipless jet needle and lighter diapharam spring, retaining the accelerator pump, and viola. I can literally wack the throttle open in 1st gear at idle, yes idle and it just starts pulling until 3000 rpm and then gets crazy. In 4th or 5th it just starts pulling away from 3000 with out a hitch. Plugs stay light grey/light brown in all kinds of riding. Summary is too rich can some times act exactly like too lean. I believe you now have the KEY. Bob | ||
| Hugie03flhr |
At this point, if it was me I wound go back to square 1 and start over. Too many mods in a almost stock application IMO. | ||
| Nocompromise |
Bob - thanks for the info - it ran great today at Infineon with just a little bit of pinging from time to time. When Jim and Terry get their dyno shop up and running I'll take it to them. William - "almost stock" = 1250 kit, Stage 2 XB heads, 536 cams, HSR42, Force race pipe, Race air cleaner, Dyna 2000 adjustable ignition module? | ||
| Jackbequick |
I've found the Night Rider web pages to be the best single source for details on tuning and hopping up the H-D V-Twins. Their V-Twin Cafe' Motorcycle Performance Guide is the starting point for a lot of useful info. Start with the Harley-Davidson Modification, Installation, Maintenance and Repair Index to find the info you want. I used the page on doing the CV-40 mods to do the jets and mixture screw mods on my M2. I was new to Buells and H-D engines and it really helped sort it all out. The "Step 9 Fine Tuning" section there describes how to do the road tests to sort out the too rich/too lean quandary. I was okay with reading spark plugs but it covers that well too. My M2, with the jet size and idle mixture screw mods done and running perfect, always showed plugs that were a light tan with a touch of gray on the the rear cylinder. It was very reassuring to know I had it right. Back at the Harley-Davidson Modification, Installation, Maintenance and Repair Index you can use the links from the various section headings at the top to access how to do it info and/or documentation from manufacturers. You'll find stuff for many of the commonly used cams, carbs, and ignitions there. The various articles there have me pretty well decided that the future for my '97 Dyna will probably be the 84 HP Stage 3 setup with the SE heads and the CV-40. I'm at 56,000 miles now and am happy enough with the stock 65 HP engine but would not rebuild it to those same specs. I don't want or need a lot more power, 84 HP should give me all the power I'd ever want or need for an occasional cheap thrill or more heavily laden bike. I am a geezer, my FXD is a geezerglide, everything is in harmony. :>) Jack | ||
| Cyclonecharlie |
Kevin, Let me give you my take on this, I've done a lot of mikuni carbs. on dirt bikes and some street, also a lot of CV carbs. With the mikuni carb you have a cable that goes straight to the slide,you move the throttle and the slide does the same.You snap it open and you have a big hole with little to none air flow(a lag). With the CV carb.it's different, you can snap it open but the slide is only going to move when you have enough air flow to make it move(no lag)Now all this is at low RPM's,at 3K and above the Mikuni will snap your head off,where the CV is still just smooth. My thinking, educate your right hand to get the most at any RPM and you will be way ahead of the game.  |
