650/X-2 Issues with my chicken

[rollin5150]

Just finished putting a blown up chicken together. It has 650 with a coffman pipe and a 38 CDKII carb. The ski starts on the trailer and revs good. I left it on the trailer on the ramp to get the low speed circuit and idle dialed in. It is hard to start when in the water and will only stay running if I have the idle turned up (around 2000rpm or so). With it running, I then have been trying to set the low speed adjuster but am not getting any RPM change at all. I have tried from closed up to 3 turns. At any setting, the idle cannot be dropped or the engine will die. If you touch the throttle it will die. I am thinking that either my jetting is way off or I have a fuel delivery issue. The jetting is at 175 high and 75 low. Compression on each cylinder is 165psi. Any ideas on something I have overlooked? Could this be electrical as well? The carb was rebuilt before installing.

 

[WFO Speedracer]

A couple of things to check, the idle circuit on Kehins is kinda finicky, pull the carb, pull the outside cover off, under that cover is a single screw, remove that screw and remove the plate assy, under that plate is a black piece of plastic, under that are the bypass holes, make sure they are clear, if they are clear you will probably need to lower your popoff pressure to make it idle properly, you can use Mikuni springs to do this or order a different spring for the kehin carb.

You say the carb was rebuilt, if for some reason you changed out a popoff spring when you rebuilt your carb therein lies your problem.

 

[rollin5150]

Thanks for the reply WFO. I do remember reusing the same pop off spring. My fear is it is the carb. I soaked it for a few days and blew out all ports with carb cleaner. It looked like it sat with water in it for a while. I will go back in again and report. A buddy emailed me asking if I wanted to try a 40 size carb so I may swap that in as well

 

[rollin5150]

Well, well, well...interesting day realizing my stupidity. Pulled the carb and found this


I then measured the carb and found it to be a 40mm carb, the 38 was a spare that came with the ski. That explains the jetting that was in there. I had totally forgotten that I had no screen on the supply drop down tube and no filter on the gas line. I am replacing all fuel lines and adding the filter.