My jet motor won't start!

Too close to the jet fire or fire too hot. Check pressure on line, or jet size too wide or jet is it for propane gaz or natural gaz?

http://www.us.kohler.com/webassets/kpna/catalog/pdf/en/1198327_2.pdf

Call 1-800-4KOHLER 1-800-456-4537)

some parts are under warranty,call them b4 you do anything,they will help figure it out,the link is your manual

the main jet is open before the pizo starts
for safety sake have a gas fitter look at it

Check the jets on the bottom sounds like they are blocked

thermocouple/dirty pilot jet

Call service technician.
Call Boch Phone: 608/257-2225
http://www.bockwaterheaters.com/technical/engineering.html

I don't see a service manual posted on internet.
Without a service manual showing ohm-readings for testing different parts, you are left guessing which part is problem.
Most water heater manuals today recommend yearly service to catch up on most causes for failure including air in fuel line, dirty or corroded burner parts, defective sensor, loose connection, etc.

First thing to do on any gas job is check the fitting line for leaks.
If the piping you are connecting to is "gas tight" then your good to go.
Usually on the compliance plate on the unit there will be a jet sizing chart, find this , it may be on the inside of the cover or on the side at the top.
The jet size for propane is a smaller size orifice than for natural gas,
I use a tiny set of thumb drills to drill the jet to the required size for that burner. (the jets are normally made of brass and are quite easy to drill by hand)
It can be a little bit fiddly actually getting the main burner out of the unit so you can work on the jet. Also very important is that you make sure that you have the exact size drill bit for the jet. Gas appliances can become hazardous if improper jet sizes are fitted!!
This may not be a task for a novice, if in doubt, get a qualified gas fitter to check your work.

The pilot light jet may have got a little bit of dirt or grit in it which is preventing it from keeping alight. Try probing the jet with a fine piece of wire to see it the blockage can be dislodged. You may have to unscrew the jet to clear it by blowing air through it. Make sure gas is turned off first before removing any parts.

The pilot light also has a thermocouple that allows gas to the pilot light while the flame is burning. If flame goes out it shuts gas off to the pilot jet. The thermocouple is bypassed by a switch during the initial ignition and once the thermocouple warms up after a minute or two of holding in the bypass switch, it should maintain the pilot. If, after cleaning, the pilot light keeps going out, it would seem that your thermocouple is faulty and needs to be replaced

Yes you should be able to adjust the eyeball. Simply grab it with your fingers and move it where you want it to be. Some jet trim are adjustable from the outside face of the jet. take a hold of the outside of the trim and turn it both directions until you feel more water pressure come out. this means the jet is open.