650L Mikuni 42mm pumper install

[jeremy_77]

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?

[garthr]

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

[jeremy_77]

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?

[jeremy_77]

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

[jeremy_77]

from what I can tell, I need to go bigger on jets

[jonr3]

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.

[Mr.Xr650l]

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

[ncc6462]

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.

[ncc6462]

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.

[ncc6462]

Sorry for the duplications folks. Kept getting errors from Thumpertalk Server

[Mr.Xr650l]

http://www.mikuni.com/pdf/hsr_tuningmanual_021003.pdf Edited July 19, 2013 by Mr.Xr650l