So I took out the CVK carb and put in a Bill Blue modified mikuni TM33 pumper today.
I've only ridden it 5 miles since the swap so I can't comment on milage but the throttle does seem more responsive. I'm hoping the carb makes the bike easier to wheelie. I'm not too good a wheelies but find them really tought on this bike.
The install was not a complete drop in, but almost.
I had to shim out the top of the coolant catch tank because the tank was interfering with the choke cable housing. I used a large nut for the shim and a longer 6mm bolt. I could not use the short pull-on choke plunger that the pumper carb came with. The coolant catch tank was in the way. The stock klr250 choke screwed right into the pumper carb and seems to work fine.
I bought the carb used and it came with a modified set of upper engine mount plates. The right plate had a small recess cut for the top of the tm carb. I needed to use the plates as the stock right side plate would hit the top of the carb.
The tm has been modified to only work with the pull cable (unless I am not understanding something). So I detached the push cable from the throttle housing and covered the hole that was left in the throttle housing with some tape.
I could not get enought slack in the pull cable at full right lock. I ended up removing the adjustment nut on located on the throttle housing end of the cable and had enough adjustment on the carb side of the cable to make it work.
The fuel drain screw is hidden behind the coolant catch tank. I like to drain the carb bowl when the bike is going to sit for more than a week, so I am not sure yet how I am going to address that.
So I need to ride it more to get a good feel for it, but the pumper carb is in there and working.
The modified tm33 had a 137.5 main and a 37.5 pilot jet.
Has anyone ever ran witout a coolant catch tank? That tank is interfering with the choke(shimming it took care of that), and makes accessing the float bowl drain screw tough or impossible (I have not tried yet). If I could get rid of the tank I would not have those problems. Both the KLR250 and my DRZ400 never seem to vary the amout of coolant in the catch tanks, so I am not sure how necessary they are.