jeremy_77 My Ride Posted May 8, 2013 Looking for some help. Are the only hoses that I Hook to this carb on a 650l the fuel hose, and the drain hose on the bottom? I know I leave the vent above the fuel port open, what about the other 2 nipples/ports? Cap off? Share this post Link to post Share on other sites
garthr Posted May 8, 2013 i have a mikuni tm40. it has one vacuum port on the right side. if you have 2, id cap them off. the only othe connections would be fuel inlet, and drain/ overflow. garthr Share this post Link to post Share on other sites
jeremy_77 My Ride Posted May 8, 2013 Ok thanks! I thought so. What about the choke hook up, it's on the right of carb, is that a issue? Cable will reach? And jetting, xrs says it is right for my setup. I have fmf power bomb/ q4 exhaust, drilled air box with kn filter and snorkel removed. Running fmf power up kit jets and needle, main is 165 and pilot is 58. I believe the mikuni has 150 and 22.5. Do I need to step these up? It came with some extra jets, 152.5/155 and 25/27.5 I think? Share this post Link to post Share on other sites
jeremy_77 My Ride Posted May 11, 2013 Tuning: Ok I need help tuning. It has a little hesitation when I blip the throttle. When coasting down it backfires/pops more then my old carb with fmf powerup jet kit. When I blip the throttle it puffs out a little black smoke. I have messed with air screw, turn in all the way, about half turn out it runs, and backing out 1.5 turns it runs rough again and dies. So I have it backed out 1 1/4 turns. It seems like a very small window where it will actually even stay running, the fact that it wont run at 1.5+ turns make me think I should not switch up to a bigger pilot jet, but 1.25 turns is not much. Please help Also It seems like at about 25-50% throttle it has a little hesitation too Share this post Link to post Share on other sites
jeremy_77 My Ride Posted May 11, 2013 from what I can tell, I need to go bigger on jets Share this post Link to post Share on other sites
jonr3 Posted May 11, 2013 It sounds as if the pumper jet is kicking in too fast. I had the same problem. Back it off some to allow the RPMs to come up more before the pump kicks in. Share this post Link to post Share on other sites
Mr.Xr650l Posted July 12, 2013 (edited) Mine runs great with the pumper disconnected. I would say first unhook the pumper, then get the bike running good with jets and needle clips and so on , and then re Introduce the pump, and /or u may find you don t need it:D 10:5:1 680 big bore 142.5 main 25 pilot 95 needle2nd pos Edited July 19, 2013 by Mr.Xr650l Share this post Link to post Share on other sites
ncc6462 Posted July 14, 2013 I am interested in this discussion because I recently purchased an 2007 XR650L. I really do not like the carburetor. I have seen both the Mikuni pumper and the Keihin FCR. I have had bikes with the Keihin FCR and it has been the easiest carburetor to tune that I have ever worked with. (Been messin with bikes for 34 years.) I have never used a Mikuni pumper. Was there a particular reason you went with the Mikuni over the Keihin? Thanks. Share this post Link to post Share on other sites
ncc6462 Posted July 14, 2013 I am interested in this discussion because I recently purchased a 2007 XR650L. I really do not like the carburetor. I have seen both the Mikuni pumper and the Keihin FCR. I have had bikes with the Keihin FCR and it has been the easiest carburetor to tune that I have ever worked with. (Been messin with bikes for 34 years.) I have never used a Mikuni pumper. Was there a particular reason you went with the Mikuni over the Keihin? Thanks. I am interested in this discussion because I recently purchased a 2007 XR650L. I really do not like the carburetor. I have seen both the Mikuni pumper and the Keihin FCR. I have had bikes with the Keihin FCR and it has been the easiest carburetor to tune that I have ever worked with. (Been messin with bikes for 34 years.) I have never used a Mikuni pumper. Was there a particular reason you went with the Mikuni over the Keihin? Thanks. Share this post Link to post Share on other sites
ncc6462 Posted July 14, 2013 Sorry for the duplications folks. Kept getting errors from Thumpertalk Server Share this post Link to post Share on other sites
Mr.Xr650l Posted July 14, 2013 (edited) http://www.mikuni.com/pdf/hsr_tuningmanual_021003.pdf Edited July 19, 2013 by Mr.Xr650l Share this post Link to post Share on other sites