[nitromechanic]

Just bought an 03 450R (set up for flat track) and I'm having issues getting the jetting correct.

jetting when purchased;
175 M
42 P/screw @ 1 turn out
77 starter
100 air
55 leak
OBEL R needle on 6th groove
Hot Cam S2
Kibblewhite springs/Black Diamond valves
White Bros exh
air box heavily modified

bike was very difficult to start, no valve clearance. Had a local builder do a top end/valve adj.
Bike was still difficult to start; floods very easy.
When it did start, it would not idle worth a darn. If you did not move the throttle after start up, bike would idle for a few seconds and then jump up. As soon as you throttle up, the idle would not come back down to normal. I checked for air leaks, none found. Turning the fuel screw out to 3 turns helped, but did not cure the idle issue.
I purchased the JD kit; installed red needle @ 6th groove, installed 180 main, installed 45 pilot, installed small 0-ring on AP linkage, installed 65 leak, fuel screw @ 1.5 out.
Bike still hard to start and pops out exhaust like a 2 stroke at idle. Very, very rich down low and still will not idle down correctly. Can turn screw to full closed and idle not changing.
Changed the starter jet to a 70, starts much better.
Changed back to the 42 pilot @ 2 turns out, as you turn the screw back in idle comes up, but will not come down when backing out.
Changed back to the OBEL R needle and started bringing it back down. Idle much better at 1st groove, but still not up to par. Still have the not idling down issue, just not as bad.
I measured the needles just above the tip on the one that came with the bike, the JD red, and the JD blue;
OBEL R = 2.10 mm
JD red = 2.26 mm
JD blue = 2.28 mm
did not measure actual taper.

With the needle up high, bike very rich bringing revs up, it blubbers and blows black smoke. Bring the needle down and blubber gets better and gets crisp. But still have the idle problem.
I've taken the carb apart, cleaned very well, and inspected all parts. No obvious damage, but don't have any tolerances to check with.
If anyone can decipher all that stuff above, I would sure appreciate it.
I used to think I was ok at carb jetting, but I'm really lost here.
Thanks.
Patrick

[Asmith]

Have you had the slide out of the carb?

If so, it was put back in upside down.

[nitromechanic]

I made that mistake before, not the case here.


Installed my X carb on this bike and she runs good.

[Skoot22]

Try disconnecting the TPS and see how it acts.

[paul turner]

Might be one tooth off on the cam timing.


paul