Rering'd her, now doesn't start as easy (08 450sxf)

Okay, so from previous posts I tore my top end down and put rings in my 450. I thought I had trouble with the cam timing but, ruled it out as a weak battery when it wouldn't start upon reassembly. Last weekend, I rode the bike for the first time at an indoor AX. The bike didn't want to start as readily as it did before I touched it. If it didn't run good, I'd suspect I may have did something wrong with the cam timing, but it ran great. Being cold out, I thought it could be my pilot jet. I'm running the JD jetting kit and they spec #42 pilot and don't suggest changing anything for cold weather. I put a 45 in tonight with no noticeable improvement. Last Nov, the bike fired in 19 degree temps (F) by three cracks of the throttle and the choke. Last weekend, it was in the high 30s and I had to crank and crank before she lit. It seems like the bike starts easier with the throttle open a little. I put a new spark plug in it during this rebuild. I half assed looked at the plug gap before throwing it in. I may relook at this. Finally, I've noticed that when the bike is warm, sometimes if I give it a quick push of the E button and no start, when I hit it again, I get a flame shot before it fires up. I don't remember this before but, then again I wasn't looking. I guess it makes sense that some unburned charge could ignite in the exh sys when the engine fires but.....

When you put back together did you check your valve clearance?

Have you tried back out your fuel screw 1/4 - 1/2 turn?

Yeah, my valve clearance measurements were all in spec. Funny thing, it seems since I installed the JD kit, fuel scr adjustments aren't really noticeable. I'm gonna call JD today. BTW, I pulled the plug and regapped. I cracked the throttle, chocked it, hit the button and she fired right up and stalled. After that I had to crank and crank and she didn't start until I opened the throttle wide. This is not hot the bike used to start.

Are you sure the pilot jet / circuit is free/clean ? I mean it sure sounds like there´s something wrong there. Think about it ; You twist the throttle a few times (thus activating the acc. pump) and the bike fires right up (and when the gas squirted in is burned up it stops) or you keep the throttle open (now you activate the main jet circuit) and it starts.

I would dig in the carb quick as a bunny...


Good point. The notion that the pilot jet could be plugged was suggested and acted on with no luck but, I suppose something within the circuit could have something in it. I just got done tearing around the neighborhood with it. I nailed it in 1st in the church parking lot lit up the back tire when it came on the pipe:thumbsup: BTW, I talked to JD this morn and she suggested I try the blue needle (low elev- I'm at 4500 ft) @ the 3rd clip. She also suggested I looked at the fuel scr. I'm running the R&D flex scrw and she claimed the taper on their part has been suspect on some occasions. I guess I'll compare it to the stocker when I look at the pilot circuit.

Yep. That´s where i would start. The PJ circuit. Something is funky there.

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