| Author | Message | ||
     Eboos |
I was reading many posts about carb jetting, and I came across 2 different thoughts on this. http://www.nightrider.com/biketech/hd_cv_mods.htm I found this page that suggests using a 165 main jet with a N65C needle and a #45 slow jet. First, what is the effect that the N65C (1988 XLH) needle has on the main jet that would make it nessesary to use a rather rich jet? Next, I noticed a lot of posts where people are using a 195 or richer main jet. Now I have a K&N carbon fiber intake, and I plan to switch from stock to D&D slipon exhaust. Should I be looking at the richer end of the spectrum? | ||
| Buellistic |
Erik(AKA Eboos): Have a 97S3T which still has LIGHTING HEADS(pre-thunderstorm)... Running a 200 main jet, M2 CYCONE needle, 42 low speed, 97 exhaust header with a 98 muffler ... MY OBJECT IS LOW END TORQUE !!! WHAT ARE TRYING TO TUNE FOR ??? In BUELLing LaFayette | ||
| Eboos |
Ridability. I want it to run well throughout the rpm range, and at all throttle positions. My bike has been coughing, and cutting out (stalling) while riding as if it was out of gas. | ||
| Jackbequick |
Erik - I have a 2000 M2 also. It stumbled and jerked at lower RPM, it was unpleasant to ride at low speeds. I changed to a #48 slow speed jet and uncapped the mixture screw and set it at 2-1/2 turns and it made all the difference in the world. I did not make any other changes, the main jet was a #195 and it has been fine. I later changed from the stock airbox to an AFT air cleaner with a K&N element and the #195 main jet was still okay. I don't do any full throttle or high RPM riding. I also replaced the manifold seals while I had the carb off as there was a possibility that part of my problem may have been an air leak there. Leaky manifold seals are a fairly common problem on the tubers. And I gave the carb a good cleaning while I had it off. Pulling the manifold, replacing the seals, and doing the carb work is pretty simple, the article above and the service manual describe the procedures nicely. Or you can browse the KV for the details or ask here. I'd try replacing the seals and doing the #48 slow speed jet and mixture screw adjustment first, those are easy to do and have solved a lot of problems in the past. Jack | ||
| Buellistic |
Erik(AKA Eboos): RIDABILITY- As a "PREVENTIVE MAINTAINENCE" thing you should replace the intake manifold seals every two(2) years ... By your profile you have an 02 M2, so the seals should already been replace two times and again some time in 2006 ... REMEMBER: "AN OUNCE OF PREVENTION IS WORTH A POUND OF CURE" meaning your engine will not start running like crap in the middle of no where ... In BUELLing LaFayette | ||
| Ara |
Ditto Jack's comments on the #195 main jet. I do fine with a #45 pilot jet, though. I have a completely gutted air box, H-D venturi ring, Stage I Dynojet carb kit (but kept the factory emulsion tube - it's better), and a K&N filter. I ran the #205 main jet that the Stage I kit came with, but on Blake's advice replaced it with the original #195. Blake was right. Hey LaFayette, what are the part numbers for those intake seals on the '97 S3s? My dealer has lost his parts book for the 1997 bikes. Thanks in advance. You're always so knowledgeable and helpful! Russ | ||
| Buellistic |
Russ(AKA Ara): Seal, intake manifold PN 26995-86B ... NEVER ACCEPT -86C as they are NO GOOD !!! Just incase, the SEAL RING, carburator PN 27002-89 ... THESE ARE "SPORTSTER PART NUMBERS",if the PARTS TECHNICAN does not know, what about the Harley-davidson TECHNICIANS in the back ??? "ONE OF THE MOST DANGEROUS THINGS IN THE WORLD IS A HARLEY-DAVIDSON TECHNICIAN WORKING ON A BUELL !!!" In BUELLing LaFayette | ||
| Ara |
Thanks very much, LaFayette! | ||
| Tlagocj |
Hi LaFayette, do you know if these parts numbers are the same for my bike, a 1998 S1W White Lightning ? thanks, Tim in Beijing China | ||
| Buellistic |
Tim(AKA Tlagocj): The "TUBE FRAME BUELLS" have the same engine as the 1203 SPORTSTERS ... The things that a BUELL owner would need, ie: carbuator parts, Drive BELT, clutch/transmission are the same, rocker arm cover gastets are the same ... Have a 97S3T and the parts numbers are the same as SPORTSTERS ... DO NOT go into a HARLEY-DAVIDSON DEALER an tell the "PARTS TECHNICIAN" you have a BUELL as they will go BRAIN DEAD and say they do not have PARTS for a BUELL, when most of the SPORTSTERS engine parts are the same ... Just say you have a 1203 SPORTSTER !!! In BUELLing LaFayette | ||
| Bensford66 |
I have a 2000 M2 with white brothers slip on, and a Forcewinder. I am looking at the K&N Jet Kits ending tomorrow on Ebay and want to know what one to get. I've never done this and don't want to spend a bunch of $$$ on multiple attempts. Can anyone tell me which one to get? | ||
| Jammer |
Bensford66, Dont use a "jet kit". follow the procedures outlined in the Knowledge Vault ie... shimming the needle, larger slow speed jet. I believe this would be the easiest way to go. | ||
| Jackbequick |
Ben - What Jeff said! I have a 2000 M2 also. I changed from a #45 to a #48 slow speed jet, drilled and removed the access cover from the mixture screw and set it a 1-1/2 turns, and replaced the intake manifold seals (rubber, they don't age well) and it made a miraculous improvement in warm up and slow speed smoothness. The bike was just all round better for it. I also dropped the float bowl cover and gave the carb a good general cleaning with aerosol carb cleaner while I had it off. Mine had a #195 main jet, I left that, did not change the needle position, nor did I drill any holes in the slide. And the mixture was fine across the range. I later added an AFT after market/low restriction air filter and did not have to change the main jet for that. But you may have to change the main jet for the combination of the air filter and exhaust. You might find it interesting to do the seals, the jet change, and add the air cleaner first. Then try that out for a while before you put the new muffler on. That way you can make sure the mixture is right before you add the muffler. Some of the remarks in the KV archives indicate that the stock muffler is hard to beat as far as low end power and smoothness. It is well engineered and holds it own on HP and torque with the after market stuff in dyno testing. Not much power gain from the after market mufflers. My impression is that the main thing gained is more noise. Which is exactly what some people wanted. Welcome to the gold mine for good info on the older Buell bikes. If you have any trouble figuring out the KV, post that here and we can offer some help. There is probably nothing that you need or want to know about your M2 that is not in the Knowledge Vault and there are some regular readers here that had a lot of fun learning it all hard way and who will share their knowledge with you. Jack | ||
| Jayvee |
OK here's one that might not have come up. 2000 M2 bought used, I now have the Race Kit K&N, and a Vance & Hines slip-on, and runs fine, no idea what jetting is though. Want to change to Forcewinder, and stock muffler. My guess is the Forcewinder wouldn't make much difference, but the muffler? Any advice as to starting points? Also, is "slow-speed jet" the same as "pilot jet"? Thanks. | ||
| Buellistic |
Jayvee: Running a stock muffler which is product improved to perform like the XB stock muffler with a valve for low end ... Of course it does not have the valve and the sound is good ... Ping me(Ljenne73c@verizon.net) and "i" will send you a picture !!! Running a force copy in my AIR BOX(FORCE in a BOX) which runs good and keeps some of the intake noise down ... There is a idle mixture screw, low speed jet, needle, and HIGH speed jet ... In BUELLing LaFayette | ||
| Jackbequick |
Jayvee - Proper name is slow speed jet, pilot jet as used above is referring to that jet (the one in the #45 to #48 or so range). His a good link with cutaways and description of the work. For the most part, to get yours back to stock and with the basic tweaks that make a stable smooth running engine, you want to: 1 - go to a #48 slow speed jet, 2 - remove the idle mixture adjusting screw cap 3 - set idle mixture at 2-1/2 turns 4 - have a #195 main jet (or close to that) The link above details some other work like drilling a hole in the slide and raising or changing the needle but I'd hold off on that until you have done the basics. The rubber seals between the manifold and cylinder heads need to be replaced every 2-3 years probably. They are prone to leakage and that leads to rough idles and a bunch of other problems. They are pretty easy to replace and there are good descriptions of the tricks that make it easier to to get the allen head cap screws in and out in the KV. Jack | ||
| Bigdog_tim |
Thanks to Dave at Appleton's I found this thread (where would we be without Dave!). I live in Seattle (read - close to sea level) but there ARE some serious mountains here. Most riding will be between sea level and 1000 feet. I have a 2000 M2. Currently, it has a 165/45 in it. I also have a K&N Air Filter and a Vance and Hines exhaust. When I bought the bike, it was needing some work and I just decided to rejet since I was already looking at some fuel related problems. When I got the bike, it had a 200/42 in it. The local dealer recommended the 165/45 along with new slider. My question: Those of you that are running something bigger than 165 where are you (relation to sea level)? I don't have a friendly dyno shop (am still looking). Of course, I can go through some plugs to see what there is to see. I am looking for general ridability and more HP. On the HP - I want this bike to be my hooligan bike - snapping wheelies in 1rst and 2nd. As it is now, can't get it up in 2nd (first gear is not a problem). Thanks! | ||
| Jackbequick |
I did the #45/#195 thing as detailed above. That had my M2 running so good that I never even considered messing with the carburation again. #165 sounds too lean to me. What do the plugs look like? I live at sea level in Maine and probably never used the M2 over a elevation of 1,500-2,000 feet ASL. The M2 was one of the Buells with a little extra wheelbase. That well suited its character as a sport bike capable of hauling a passenger and not being too bad for longer rides and trips. That extra wheelbase is probably inhibiting your "hooligan bike" goal a little. Jack | ||
| Hans |
On the original carburettor is the throttle not directly connected with the needle, which regulates the mixture. The needle is connected with the membrane in the carb body and that membrane reacts on pressure differences. It has an self adjusting effect on the mixture at different air pressures (or elevations). The too much praised aftermarket Mikuni has to be adjusted for different elevations. Hans | ||
| Blake |
Jack, Pretty sure that all the tuber Buells have the same wheelbase, 55". | ||
| Jackbequick |
Ooops! Anyone smell a brainfart? I thought I remembered reading here that the M2's were longer than some of the other tubers. But I guess I was wrong. Thanks for setting the record straight. Jack | ||
| Bigdog_tim |
Thanks for the replies. I think the size of the jet (s) is a function of airflow. The elevation matters. What works good in Denver will be different in Seattle. That being said, I need to check plugs often (until I find a dyno nearby. | ||
| Blake |
Right, but lower elevations warrant larger jets, not smaller. There is a possibility that your carburetor had some extensive rework/tuning performed on it and that the 165 main jet is the perfect choice. But I've not ever before heard of that small of a main jet being used in the CV40 OEM carburetor of a Buell twin. | ||
| Hans |
Bigdog-tim, The main jet has a variable opening because the tapered needle fixed at the diaphragm. The diaphragm travels up and down by the different pressures on both sides. One side is under atmospheric pressure which counteracts the pressure on the other side by the venturi effect of the flowing air. The atmospheric air pressure has its own effect on the airflow. Besides that: The gas is pressurized into the jet by: The variable air pressure at different altitudes. The Keihin compensates remarkably well for differences in air density. Of course, the engine has less power on high altitudes, because it swallows there less molecules of the air/gas mixture with each stroke. Hans | ||
| Alex |
195 to 200 sounds good for a Buell with stock CV carb. 165 sounds good for a Mikuni HSR 42. Donīt mix them up. BTW, the main jet has NO variable opening size (for it is a simple jet with a fixed hole in it). The jet needle (part of the carb slide) forms a variable opening together with the needle jet (part of the carb body) according to the slideīs height. When the slide is high enough the smallest part of the jet needle together with the needle jet forms an opening usually bigger than the main jet size thereby causing the main jet to restrict/meter fuel flow. This is an interesting point as in some high fuel demanding applications there will be a point where bigger main jets will not deliver more fuel (as the opening between the jet needle and needle jet is smaller than the main jetīs size). So a change to a bigger needle jet would be required. Regards Alex | ||
| Mrsmichele |
I have a 2001 M-2 with a force wind intake V&H slip on. It's jetted at 48 and 195 and the mix screw is set at 2 1/2 turns out. It runs super unless I'm racing through the gears. then at around 4,500 RPM's it will sputter. Should I go with a larger main, 200 or a 205, or try adjusting the mix screw out a little more? I'm very new at this. I've only been riding a little more that a year. I started with a Blast last year to get comfortable, upgraded to the Cyclone this year. | ||
| Jackbequick |
At 4,500 RPM you're off the low speed jet and on the main jet. But the jets you're using and the 2-1/2 out are a well proven combination for clean smooth running on the M2. If anything, with the lower restriction on the intake and less back pressure on the exhaust, I would expect you might have to a richer (higher numbered) main jet. I would not hesitate to try a 205 on that. But your symptoms are not typical of it being too lean at higher speeds, you may have another problem. It sounds more like too rich, intermittent fuel flow, or maybe even the ignition breaking down a little at higher RPM. There is good info here on doing the mods you're already done and some hints on reassembly that may be helpful. http://www.nightrider.com/biketech/hd_cv_mods.htm# slide_detail I sort of wonder if there may be an issue with the diaphragm not being fitted right or leaking. A look at a plug would be helpful too, it is much safer for the engine to be a little on the rich side rather than the lean side. Too lean can have the bike running great but it can melt holes in pistons. That page has a trouble shooting link for that carb too that is pretty good. You can ignore the info there on drilling out hole the carb slide and on changing to other needles. You should be able to get that running fine with just the jet size changes. If it has not been done recently, you are due to replace the seals on the intake manifold. Those can leak as they harden from heat and age and are best replaced every two years or so. Leaking seals would normally be noticed as a rough idle or rough running at low engine speeds. Jack | ||
| Djkaplan |
It's a waste of money buying a jet kit... just buy the individual jets you want for a few dollars. I live at a 300ft elevation above sea level in Georgia (more than elevation affects jetting, but elevation is the most convenient parameter for comparisons). I have a Forcewinder and race header with a V&H muffler and race ignition... other than that, my engine is totally stock. I use the stock needle shimmed to .037", #45 pilot (#42 stock), stock #200 main, and airscrew out 2 1/2 turns. I may drop the needle down a bit in the future because I think I could run it a bit leaner based on plug color. It runs great, but mileage can drop down to the low 40's if I'm on it all day. |
