| Author | Message | ||
     Iamspartacus |
Hey guys, I was wondering if there is a comprehensive chart for jet sizes for me to reference. I've tried the search feature to no avail, so a link would be awesome. If not, can anyone steer me in the right direction for an M2 with a HurricanFlow style intake and Vance & Hines pipes (at 2,200' elevation)? Previous owner I have a sneaking suspicion didn't rejet correctly. Also, any tips on removing the carb and doing this job? I've rejetted a Suzuki, but this is a different beast. Thanks! Note: I do have the service manual. | ||
| Imadog |
I too have a hard time using the Search Utility to find what I am looking for. Maybe we need a course on how to get the most out of it. I have a 2000 M2 with Force Winder intake and V & H exhaust. The stock carburetor is a Keihin CV40, it seems there are various sized main jets used. Mine has a #200 main jet and #42 idle jet, which is called out for in the repair manual. The basic modification are as follows: #45 or #46 idle jet #200 main jet shim the needle up 0.050" 3-1/2 turns out on the idle adjustment screw drill the vacuum hole on the slide out to 7/64" radius the bottom leading edge of the slide While you are doing the job, get a carb rebuild kit (including accelerator pump). New intake gaskets, new gasket that the carb slide into. As far as tips, you will need a set of SAE ball end Allen wrenches, a modified stubby Allen wrench for getting to the intake bolts (I think it is 1/4"). Also the intake brackets are not identical, so keep them in order. It is recommended to change the float bowl mounting screws to SS SHCS (Allen bolts) I believe they are M3 x 15 mm long. The above modifications cleared up a low speed stumble and also shimming the needle smoothed out the transition between low speed and mid range. Good luck! The CV carb does a good job of compensating for changes in altitude up to 7000 or 8000 feet. But if you feel the need, remember to use smaller jets as the elevation rises. Here is a good link on the CV40 carb: http://www.nightrider.com/biketech/hd_cv_mods.htm | ||
| Jayvee |
I agree it's hard to find a chart, and, not all sizes seem to be available from a single vendor. But here's what Slow Jets I've seen: 42, 44, 45, 46, 48 And the Mains go by 5's, 180, 185, 190, 195, 200 The shims I've found are .020 each, I don't know how people get to .050 inexpensively. Then there's Jet NEEDLES, but mostly it seems they get shimmed more than changed. There's a lighter slide return spring, lets the slide come up slightly faster. Then there's drilling out the hole in the bottom of the slide, I'd guess most don't do that. There have been a couple of sizes suggested, but I'd only say you can always drill it out bigger, but much harder to make it smaller. A new slide is $40-50. I've also seen suggestions about polishing (or at least #000 steel-wooling) the slide rails and channels where it goes up and down, as well as similarly polish the back edge of the bottom of the butterfly valve. And then there's the nozzles, which I won't get into, and the issue of Accelerator Pump Or Not, polishing and or throating the bore, and my personal favorite, replacing the cap with a billet aluminum one. | ||
| Imadog |
The washers I used for shimming the needle were also 0.020". I used 2, the second one I placed on top of a small nut and used a hammer and center punch to bow the washer out to 0.030". | ||
| Natexlh1000 |
If it's an aftermarket intake, make sure the vent for the bowl isn't blocked or something. Early forcewinders used to do bizarre things at high RPM due to the Bernoulli effect of the intake going past the breather. It would build up a vacuum above the float bowl. The corrective action of this was to open up the breather with a dremel. Look here: http://www.badweatherbikers.com/buell/messages/384 2/11192.html | ||
| Iamspartacus |
Nice creative cobbling Imadog  As for my intake, it's a brand new Hammer Performance, not an older Forcewinder, but I'll look into that link... Sounds like quite a bit of work on the carb for extremely marginal gains though outside of the jets and shimming the needle. Definitely stuff to think about though, thanks! | ||
| Imadog |
There are probably no real horsepower gains, only a smoother running engine, as for the intake gaskets, they should be changed every couple of seasons. At most this job should only take a couple of hours and less then $60 in parts. I think I got gaskets through Amazon.com. | ||
| Iamspartacus |
Oh yeah, I already have the intake gaskets in hand and was planning on changing those while checking the jets. I have the $15 tool from American Sport Bike too. I don't have the rubber gasket/seal that the carb mounts into though. I'm assuming an HD dealer would have those on hand. I'll definitely consider the other tweaks- just depends how much time I have in a day before I need my wheels up and running again, lol. | ||
| Buellistic |
The three most important things to do on PRODUCT IMPROVING and TUNING your CV CARB.: 1) Correct engine TIMING ... 2) All the carb. SEALS are good ... 3) Remove ACCELERATOR PUMP ... For a copy of my CV CARBURETOR Class 101, just PM me ... | ||
| Bluzm2 |
Joshua, A good starting point is a 45 pilot and a 190 main. 200 is usually too fat. Drilling out the hole in the slide doesn't do much. Maybe on a dyno but not seat of the pants. Shimming the stock needle by .050 does help. I made a washer by filing and sanding down one the was the correct size. Use a brass washer, it's easier to work with. | ||
| Iamspartacus |
Can someone explain why removing the accelerator pump would be beneficial and what the cons of such a mod would be? Thanks guys, and thanks Buellistic for sending me all that info. | ||
| Wesbuell |
From memory it has something to do with even a moderately skilled rider not needing extra fuel squirted into the carb when rolling on the throttle. Buellistic explains the 'lady sporster rider' theory well, and I believe that I am unable to get my low speed jetting right because I didn't bother removing it! A 45 is too lean but I can't put in a 48 because of the acc pump. I was going to chase some middle ground but I think I will just remove the acc pump as Buellistic said I eventually would...hahaha | ||
| Ratbuell |
I've had excellent luck on my tubers with just a jet change and idle screw adjustment. S1W with Buell race ignition, intake and exhaust, otherwise stock: 48/195, 2.5 turns out S2 with Thunderstorm heads, X1 cams, S1W race ignition, and stock S2 exhaust: 45/190, 2.5 turns 01 M2 with Buell race intake and exhaust: 45/195, 2.5 turns. I don't drill, shim, polish, or anything else. I've used the Thunderslide kits in the past...no real noticable difference in aggressive street riding (at least not to me). The BIGGEST thing for keeping a CV happy is proper float setting, and CLEAN fuel passages. I always store my bikes with full tanks and full bowls, with the petcock closed so there's no chance of fuel overfilling the bowl in storage. I treat all my fuel with SeaFoam prior to winter storage and run the bike long enough to make sure the treated fuel has gotten through all the passages and jets (add SeaFoam to a partial tank at home; ride to the gas station and fill up, which mixes the fuel/SeaFoam); ride back home; shut off the petcock and park the bike). Once I charge the batteries...they always fire up like I was riding them 2 days earlier, and clean passages keep it from hiccuping and sneezing. | ||
| Akbuell |
Re Removing the accelerator pump: Back in the Ironhead Sportster days, with the Tillotson pumper, we removed the pump first thing, for a 'cleaner' running engine. The thinking was the constant vibration ( after all, these engines are only 45 deg away from being a 1200cc single) caused/allowed the pump to dribble or drool fuel, causing the mixture to go all over the map at steady throttle. I believe we used a number 0 rubber cork from a medical supply place down the street to plug the pumper body. The only down side was you couldn't pump the throttle once or twice at start to help starting. Had to use the 'choke'. |
