CRF 450 stalling (0-1/4 throttle)

[Lemming]

<SPAN class=postbody>My bike tends to stall then giving quick on/off revs from 0 to 1/4 throttle. At first I thought that it was due to my Z-start clutch but I can get the bike to stall when I do this in neutral. I played with my fuel screw going from 0 to 2 turns out and this did not seem to stop the stalling.

Current jetting: Main 168; stock needle in the 3rd position; and stock pilot.

The bike ran great during the 24hr race at Perry Mountian. The only problem that I had was that the rivets on the end cap came loose and I had to duct tape it to keep it on. This got me through the race but the rivets tore the hell out of the end of the pipe. To fix, I cut about 1/2 inch of the end of the pipe, put the packing back in (minus 1/2 inch), and riveted the end cap back on.

Any thoughts?
</SPAN>

 

[biglou]

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!

 

[Lemming]

I thought about going leaner on the pilot but the manual does not show leaning the pilot with higher temps. Instead it's dealt with using the fuel screw. I will pull the pilot to make sure that it's not obstructed.

The idle is about as high as I can go and still keep the autoclutch from wanting to engage, by no means am I running a low idle.

Keep those ideas coming, I have a harescramble on Sunday and I need to win my class to keep in the hunt for year end 1st place.

 

[High Lord Gomer]

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?

 

[truespode]

Are you sure it is only 0-1/4 throttle?

I went leaner on my needle and it helped greatly with throttle response.

Also, when turning the fuel screw do it a 1/4 turn at a time b/c the 450 seems very touchy to adjustments with the fuel screw.

Good luck and let me know how it goes.

BTW, I'm still looking for a review of the rekluse!!! :)

Ivan

 

[Lemming]

I'll pull my tank tonight and change the plug (although&nbsp;the bike&nbsp;starting fine), clean the carb, and check for leaks.

Ivan,&nbsp; I have too many reviews to write at work that are way overdue :ugg:

 

[biglou]

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.

 

[PeteN]

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

 

[Lemming]

I spoke with Al at Rekluse and he believes that it's a combination of slight load from the clutch at low RPM accompanied by the duration of the pumper (squirt time).&nbsp; It appears to only become a problem in hot sticky places (read ALABAMA).&nbsp; At any rate he suggested that I might "consider" at least checking and or reducing the squirt time.&nbsp;&nbsp; For&nbsp;Sundays race I'm going to increase idle and increase stall speed to compensate.&nbsp; Then I'll&nbsp;possibly consider the BK mod.

All in all, I still like&nbsp;the autoclutch, just have to work out the bugs.&nbsp;

 

[mark_england]

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?

 

[xr284]

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

 

[Hick]

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

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.