Join Date: Nov 2009
Location: Lander, Wyoming
OK, did you check the fluid flow thru the 3 low speed Transition holes under the bottom lip of the throttle butterfly plate? They get all of their fuel from the Pilot jet, as does the adjustable low speed mixture screw. I use a tiny wire bent 90 degrees to poke down thru them & back-flush out thru the pilot jet tower (jet removed of course).
Is the rubber face of the cold start enrichener plunger damaged? Plastic ferrel (choke nut) damaged? Choke cable sticking? Adjusted too tight?.
When all is proper with the carb, the butterfly plate will only expose about 1-1.5 of the low speed transition holes at about 1200rpm idle.
It is totally normal for the cam sprockets arrows to be 1/2 tooth Above gasket surface.
Valve tappet clearances Normally Tighten. I usually adjust to near Max Specs, or 1 shim size under (Never an easy fit on widest feeler). Especially on exhaust tappets, other wise too much ticking.
Spark plug is 12mm x 1.25pitch x 14mm long.
Normal compression test with valve cover still installed will probably be 77-124 psi like KLR650.
Engine compression in the KLR600 oem service manual is with the KACR DE-ACTIVATED, piece of fuel hose behind spring holding weights Open. 134 - 185 psi.
You would need a restrictor orifice smaller that you could drill to help stabilize a vacuum gauge on this large of single cylinder engine. Check the orifice size in the square cap of the vacuum fuel tap.
Modify at "YOUR OWN RISK"!
Still riding my 1987 KL650-A1. 85,000+ miles & counting