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FCR-MX won't idle with choke

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Hey guys, I'm not sure what to do. I've read and reread all of the threads that seemed applicable but I can't find an answer.

I installed my FCR-MX. Im at 3200 feet. It's got a 150 main, standard pilot etc, emp needle set to 3rd clip, and fuel screw set about 1.5-2 turns out. The problem is that it's tough to get the thing started. Before the carb change I could fire it up and walk away. Now I've got to baby it for 5 mins. It runs for about 5-10 seconds on full choke then dies if i don't turn the choke off. Half choke doesnt do any good. When I turn choke off sometimes (LESS often than not) it idles by itself at about 1150-1200rpm. Usually it idles 1100 or less and then slows down to a stall.

I've measured float height and set it correctly (pretty sure it's correct). But the bike ran the same way beforeand after I changed the float height. Was about 9.5mm now at 9mm.

The only thing that really changes idle speed is opening the mixture screw way up to 3.5 or so turns out. Then when it warms up I turn it back in. I have the flexible screw deal. I can use the idle speed screw as well, but thats not the right solution either.

I'm using a pingel petcock, and make sure I turn it off when not in use. Though I do notice that on a couple of occasions I started the bike when it was closed and if I massaged the throttle like normal the bike never died. It was harder to keep going, but it never died from an empty float bowl. Maybe it takes longer than Id think to get it completely empty? Or could fuel be leaking in? Could this cause the carb to fill to full and hard start?

Any ideas on what I need to check for, how to do it etc? Or anything I should change that might help? The bike is running very well at all rpms. It pulls hard all the way through, with no flat spots or hesitation at any throttle position. I think it might be running a TAD bit on the lean side based on the engine temps, but I'm not sure. I run 340-350F at sustained 75mph on the freeway at about 70F ambient temp. I'm thinking about going back to a 152 main, but that's neither here nor there with this issue. lol

Anyway, I'm very happy with everything at the moment except this hard starting issue. Any thoughts would be appreciated.


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i'd go for a good ride to warm up the motor.

adjust the mixture down to almost a stall, then richen back up to smoothest setting (just). maybe your choke is not closing fully? do you have a 40 pilot jet? i just switched mine to a 38 but havent tested it yet. mpg has gone to

sub 40s & the plugs are a medium to dark brown. already got a new needle jet, no difference. hoping to lighten up the plugs to a tan color & get back another 20 miles per fillup on this thing.

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The YFZ450's choke/enrichment jet is too big for the DR650. I didn't bother changing it since 1/2 choke works fine on my bike. Full choke is just a few second position then I switch to 1/2 choke. At higher elevation the problem would obviously be worse. You can get a smaller choke jet... most of the YFZ's came with either 80 or 90 choke jets. Maybe a 70 or 65? Would take a bit of experimentation that I never bothered with...

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