For those of you who don't know, another popular carb swap, is the CVK40 from the KLR/KLX650. Dave Kessler (freewhweelers), provided excellent advice and jetting info for me. I'm at sea level, and my SM has a K&N filter, 3x3 mod, and billet exhaust cap. He suggested finding a CVK40 on eBay (mine was $120 shipped), and installing the following parts which I got from Ron Ayers Motorsports using the KLR and KLX650 fiche:
145 Main Jet
N1TB needle (from KLX650) w/clip and spacer (installed at 3rd clip)
Choke plunger (I got the one used on a KX250 part 16016)
Drill out the vacuum hole on the slide to 1/8" (later drilled to 3/16" for much better throttle response)
Remove the return throttle cable since it is not needed
These are the parts I ordered from ronayerscom:
1 16009-1794 NEEDLE-JET,N1TB 1 $15.67 (the order was delayed to get this in stock)
2 16016-1068 PLUNGER, STARTER 1 $21.33
3 223C0416 SCREW-PAN-WS-CROS 4 $1.64ea (new float bowl screws)
4 92037-1401 CLAMP,JET NEEDLE 1 $1.64 (clip for needle)
5 92055-1222 RING-O,FLOAT CHAMBER 1 $8.08 (the carb I got needed one)
6 92063-1017 MAIN JET,#145 1 $6.14
7 92143-1667 COLLAR 1 $2.11 (plastic spacer goes on the needle)
Item Total $61.53
Standard Shipping +$8.00
I also had to get a replacement slide/diaphram from Harley dealer for $50:
slide/diaphragm assembly, part number 27585-88, for Kehin CVK40 carbs.*
And here is a website with more info on the CVK40:
Modify the throttle cable bracket on the carb - cut off the return cable mount, then I'll quote Dave's instructions: "The reason to modify the main cable bracket is to get rid of the extra slack in the main cable ... The area that the cable mounts to the bracket is what needs to be modified ... You have two 10mm adjusting nuts that clamp to each side of the bracket ... The area on the bracket where the bottom adjusting nut clamps ( where the cable leaves the housing ) has to have material removed. There is about a1/2 inch of space in the bracket that the nuts clamp the cable to the bracket. Take a hack saw and remove half of the space about a 1/4 inch from the bottom side of the bracket. This will allow the cable to be raised that 1/4 inch you removed ... and take the extra slack out of the cable. Run the bottom nut right to the end of the threads on the cable and clamp the top nut down ... do your final adjustment on the cable at the throttle housing"
Installing the carb was a bear for me. It was a tight fit, and the carb is slightly larger where the boots attach. I had a really hard time getting the airbox boot on, even with the rear subframe pivoted away to get the carb in. The front boot clamp needed a longer screw, and the rear clamp was flipped over to allow access to the clamping screw. I don't want to ever have to pull the carb again :-)
The bike fired up immediately with the choke, and once warm idled very high. The easy way to access the idle screw is from behind the coolant reservoir, with a long flat blade screwdriver. It adjusted easily down to a smooth idle. Dave tells me he took the flexible idle adjuster from the stock carb, and used it with the CVK.
I just got back from a 2 hour ride. The bike runs great! The re-jetted stock carb would lift the front wheel slightly on a drop throttle roll on in 1st, but this time it came up quite a bit, and surprised me! Bike runs great everywhere especially mid to upper rpms. It pulls well in 5th thru 90mph then tapers off. It was very windy today, and in one section I could hit 100mph (could only do about 96mph with modified stock carb) with the wind coming at an angle behind me. Pulling the clutch and chopping the throttle from a high rpm run, the engine drops to idle immediately.
Edited today, since I drilled the vacuum hole in the slide to 3/16" per Dave's suggestions. Much better throttle response. I've added "E" cams too, and am very happy with this setup.
Overall I'm a happy camper :-)
Thanks again Dave!!!!!