[clunacy]

I have a '06 CRF 450X and I just recently started having issues with starting the bike cold and a minor issue starting it hot.

Background:
Bought bike earlier this year and it looks to be pretty lightly used. When I bought it the first few rides the bike would fire up instantly with e-start whether the bike was cold or hot and I had no issues other than replacing the battery. But recently I've started encountering start-up issues when the bike is cold and hot.

Cold Starting Issue:
How I Start it
Blip or 2 of throttle
Pull Choke Out
Hit E-start Bike Starts Fine
~20 secs or so later put choke back in and bike dies
very hard getting it started again...unless you hold the throttle down a tad and then it usually fires back up but then...
Bike will slowly start to die once started again. Like the RPM's slowly go down until the bike just literally dies...
Unless I hold the throttle down to keep it from dying, then once warm I have no dieing issues

Hot Start Issue:
Never had to use hot start lever ever, bike would normally just fire right up with e-start
Try to e-start bike now and it doesn't want to kick over
Give bike a touch of throttle while hitting e-start and it fires right up

I have no running issues once bike is at running temps.
Any Ideas?

[JimDirt]

Welcome to the site !!

It could be a couple of things either separately or together ...... First thing I would check/change is the Pilot Jet , they can clog easily and primarily run the bottom circuit like starting , idling , low RPM's , the Hot Start Plunger can be sticking (Ethanol has a large effect on gumming up carbs and the internal parts) , and just the thorough cleaning of the carb (do not just spray carb cleaner in it , you will ruin all the O-Rings and seals) , the Slide has a plate attached to it that "floats" , it has a type of O-Ring that can wear or get damaged that can cause issues , the Fuel Screw underneath at the front of the carb , should be at around 1-1/4 to 1-3/4 turns out from lightly seated

The accelerator pump could be either mis timed or possibly failing (it is a diaphragm that pumps the fuel thru a small tube that squirts into the throttle bore and gives a boost of gas upon throttle movement) , you need to test if it is working by removing the airbox(lifting the subframe along with the airbox) and physically look at the "squirt" when you work the throttle (do this with the carb in place and the gas line hooked up and the fuel valve on) , you are looking for a stream of fuel that is a solid stream , and just barely misses the slide as it is raised (basically blip the throttle (engine off) and watch the flow)

You might also want to check the valve lash , if the valves are starting to close up (Intake valves specifically) it will initially cause starting issues , then eventually progress to running issues , then the bike will eventually not run/start at all

Generally the issues you describe are either fuel or valve related ..... If the bike Backfires thru the muffler upon deceleration (when you let off the gas it will go *pop,pop,pop,pop* thru the muffler , then that is usually a lean condition , or a valve issue . you will have to troubleshoot by checking carb and valve lash to determine this

If your symptoms do not cause backfiring , then it may be something else , but more info is needed .... but that is what I would start looking into first , to eliminate or confirm those issues I described ....

As a personal note , my 06 450X as well as my 02 450R require about 6-7 blips of the throttle before starting (with the choke on) to start quickly cold .... Warm the bike will usually start right away when all is working correctly