Hey guys, I could use a little advice on how to dial in my 2006 sm610, I have installed a LV slip-on muffler. The muffler has very low restriction, a straight-through design with only the spark arrestor screen in the way. I am happy with the power output, and don't feel a need to mess with the airbox, which is stock and the filter is freshly cleaned/re-oiled. The pilot jet is stock (a #50 I think) and still plenty rich. I will probably close the fuel screw a little because right now the exhaust smells like gas at idle, the bike starts without choke when cold, and idle is a little erratic (1300-1600 rpm) once the engine is warm. If I need to order jets again, I might reduce the pilot to 45 or so. Main jets: I started out with a 175, then went to 178 then 180. I think 180 is probably the right size main jet, as the engine pulls hard at WOT (not harder at 7/8ths throttle) and there is no hiccup or sputter or anything bad above 1/2 throttle. The problem is snatchy throttle on/off lurch and a (probably) lean hiccup at 1/8 to 1/2 throttle. The hiccup does not occur when the engine is lugging behind the throttle. But as it gets up to speed it will hiccup. I think the problem is a lean midrange. I have raised the needle from centered (position 4 of 7) to one richer. That helped somewhat (as did going from 175 to 180 main). I am thinking about raising the needle another notch. I don't want to take it all apart more than once again (ha ha) so any advice would sure be appreciated. I have heard that a needle swap is the way to go, but come on, the FCR carb has so many ways to tweak it.. I should not have to buy one of those $60 kits. But would if it somehow guaranteed I would not have to take it apart again
Try these settings. main jet--------178 If you modify the airbox cover and aren't running the sparky you might try a 180 pilot jet-------- 45 starting jet---- 85 main air---------200 low air ----------100 needle----------JD red Or a OBDVR Keihein they are virtually the same thing. position--------- 4 from top mixture screw ---- 1.5 out Mixture screw is a Zyp Tye Racing type with extended reach. I don't remember the sz. of the leak jet that I installed, I believe it was a number 60. I am using the heavy O-Ring. The O-Ring is to tie the accelerator pump arm together, if you're unfamiliar with the mod I'll try and find a pic.
Thanks rajobigguy, that should get me going. I need to study the FCR schematics and learn where the air stuff goes.. I may leave the accelerator pump alone for now and just tune for steady throttle.
Keihin needle nomenclature Here's what I was able to discern from this handy chart from JetsRus: The needle I need is an OBDVR. I think the OB part just refers to the finish (OB = not bare brass), but anodized instead. When you buy a "genuine Keihin" needle I think the OB part is implied. That's why the charts only have three letters to specify the needle's dimensions. The D is to indicate the 0deg 45' taper. The V means the dimension, clip position 1 to beginning of taper is 82.75mm. The R indicates a diameter of 2.755mm. If this little bit of detective work is correct, I am not stuck buying a JD kit and can get the needle for about 8 bucks in the same order as the pilot and air jets, which the kit does not have anyway. If you guys see something I screwed up, or alternative jets I might try, now would be a good time. I'll report back on how this works, and a total $$ spent to get the carb tuned better than possible with a kit.
Looks like you're on the right road there my friend. One more thing you should do is to swap out the original spark plug with a Irridium one, this seems to help with the mid range stumble that most of us experience (not really sure why but it works).
My 2007 SM610 has the LV slip-on. I put the JD jet kit in it and have no issues. You may want to invest in a fuel screw. Don't buy the aluminum ones since the tip is made wider than the brass screws. I like the Merge Racing fuel screw (brass) and it has a plastic T-handle for easy turning. The fuel screw is sensitive so only a 1/4 turn is typically needed to clean up the off idle response. The midrange hiccup is common on the 610. The iridium plug (CR8EIX) works great for a stronger spark and cleaner burn. The hiccup typically occurs around the 3500-4000 rpm range. The iridium plug makes the hiccup non-existent on my bike. The accelerator pump mod is also a must-have... and it's free. If you get the JD kit, you will also get 2 different orings to play with. The thick oring was a bit too strong for my personal taste and it felt jerky/choppy. The throttle was a bit too responsive. The thinner oring gave me quicker response than stock without being too "jerky" as I made small throttle changes.
Thanks guys, I think I will go for the iridium plug and extended fuel screw. Right now I have a "system" for turning the screw with no diassembly, but engine running=burnt hand. Hopefully the jets and needle will be in tomorrow and I can post a pic. Otherwise I'll mess with it again next week. MattR, did you end up running the red needle, and was there a blue one you may have experimented with?
I'm running the following jetting (Spring/Summer): Red needle (#5 notch), 180 main, 45 pilot, 2 turns out, 60 leak jet. Altitude = 500 - 1000 feet for SE Michigan. In cold weather less than 50 deg, I swap to the richer blue needle at #5 notch. When I first got my JD jet kit, I used a 42 pilot per the instructions but had decel popping. JD send out a 45 pilot and I've been using it ever since.
Good deal. I am at 700ft and usually ride at temps above 50F, so I think the red needle (equivalent) will work great. I ll the ordered all the recommended jets, needle, etc. and with shipping it came to about 42 bucks.. and could have been cheaper by getting fewer genuine keihin items. I'll post a photo of the kit when I get my hands on it..
Update: Well the spark plug came in while I am waiting for jets, so I thought I'd try it first. The iridium plug does indeed reduce the hiccups, both the frequency and severity. I almost have to go out of my way, running 4-5000 RPM with little or no load to induce a hiccup now. If it was always like that and I wasn't as picky, I might have left it alone. Of course there is still a lean midrange surge (and some pinging?) and it is still rich at idle. I can't wait to try the jets and needle, but just wanted to note the effect of the spark plug by itself.
Got the jets Finally got the jets! I must have thrown them a curve ball, ordering so many different jets at once. Anyway, here is the rajobigguy special: DVR needle (does appear to be made of brass) then left to right.. 178 main, 45 pilot, 60 bleed, 85 start, 200 main air and 100 pilot air. The 200 main air looks like a common (round) fuel jet. Hopefully these will all fit where they are supposed to go, but at the bare minimum the needle, pilot and main will be swapped out. I will try to make time to pull the carb and rejet early this week, results to follow.. :devil:
Carb work's done, hopefully.. main - 180 to 178 pilot - 150 to 145 main air - was already 200 pilot air - was already 100 starting - was already 85 (yes I wasted some money and should have done more homework, but I am glad I checked them and blasted out the air jets with carb cleaner to rule that out as the cause of rich idle. Knock about $15 off the cost of the "kit" I have cobbled together here) fuel screw - to 1.5 turns bleed - solid plug changed to size 60 needle - DVR on 5th clip position (going to err on the side of rich midrange) That's it, I am putting it back together this evening or tomorrow for a test ride.
Conclusion: Very good running. Hiccup 100% gone and almost no piston-tinkle whatever the load, RPM or throttle. Thanks rajobigguy and MattR for the help!
