CRF 450 stalling (0-1/4 throttle)

Just a few "WAG's" here: Pilot too rich for that hot, humid, 'ham weather? Pilot jet partially obstructed? Is there a "BK Mod" for the CRF's? (To adjust the duration of the accelerator pump squirt) Have you tried turning the idle up a bit? That seems to help, although too much can be a problem at times.
That's all I've got!

Tooner checked the duration of the squirt on mine and said it was fine...no need for the BK carb mod.

Just another WAG...have you switched the plug (again)? Checked the intake boot for leaks? Cleaned the carb?

A quick note on using the pilot screw-It can only adjust within the range of the pilot jet you have in there. Sort of a fine tune for the pilot jet. Beyond the jet's capacity, you have to bump it up or down accordingly. At least, that's the mental picture I have in my head of how that all works.

I have a CRF with the Rekluse Z-start clutch too and mine will do the same thing. If you are abrupt with the throttle of idle, it'll die. I've tried adjusting the screw and even going richer on the pilot. Leaner might be better, but I'm getting a pipe, so I'll probably wait. I had it happen twice last weekend on starts racing Supermoto. But luckily, the main problem was some guy jumped and I backed off suddenly, so they called them both back! :) I was having a great day and nothing could go wrong.

I really like the Z-start, with it and the holeshot device on my fork, I've only been beaten on a couple starts since I got it. It reduces rider work load and eliminates stalling in all other situations. I almost worry that if I crash and get hurt, it'll keep running till it runs out of oil!?! I've only trail riden with it a couple times, but it's almost like cheating, technical hill climbs are much easier. And it eliminates the need to gear the CRF down for woods riding, it's almost like having a wide ratio gearbox. I've had to adjust it once, but I'm not really sure how close the initial setting was. For a guy who hates automatic cars, I am surprised how much I love this clutch. FYI

i have the same thing z-start etc
i was thinking of leaning out the fuel screw a little , but reducing the squirt time a little makes sense too.
are any of you guys running a flywheel wieght? would this help?

i had an 11oz weight in my crf, which i absolutly hated, lost to much snap, took forever to rev up.

Originally posted by Lemming
At any rate he suggested that I might "consider" at least checking and or reducing the squirt time.

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You may also look into changing your leak jet, although I don't see any alternative sizes avail. on the parts fiche. You could probably get one from Sudco (although there isn't one on their parts diagram either) or Carb Parts Warehouse.

Hope this helps.