The surge thing...

[Masu]

Ok just a little help needed here.

I have a 95 RMX250R

Mods
TwinAir Filter (recently cleaned and properly oiled, no rips or tears, seals well)
No air leaks that I can find in the bike
I have a RB Designs breathed on carb, a PWK38

SJ #50
MJ #175
Needle DEK clip is on the 4th clip from the bottom (I always forget how to read that)
A #7 Slide moded by RB Designs
The air screw (AS) is at 2 1/2 turns out from closed.
Plug is dark brown

I run Hi-octane fuel at 30:1 mix

V-Force Reeds
FMF Pipe with FMF Silencer



The bike runs very well, the power is so smooth of the bottom all the way to the top.

The problem is that I have had to screw the idle adjusting screw in a lot to get it to idle, (not the AS, but the screw thing that actually lifts the slide a bit)

After WOT, with the throttle closed surges along, also when I come to a stop, with the clutch in the bike idles very high for about 25 seconds (I've counted), then it settles down and idles well, in traffic this is a pain.

The gas in new, the oil is good, and the carb vents are clear, and the tank vent is too.

Is this a lean or rich problem?

I'm looking at the pilot ciurcuit here, I'm thinking of changing the SJ to a leaner one, a #48 or #45 as I think it may be rich, due to the color of the plug (dark brown) but I seem to remember that the surging problem, with the throttle closed after WOT is a sign of lean jetting....

Help me out here guys, I have a riders training session (Gymkhana in Japanese) on Saturday and I want/need smooth power.

Cheers!

 

[RM_guy]

Try turning the air screw in. The slow speed circuit is lean.

 

[clw]

Way lean, maybe an air leak somewhere. Inspect the carb boot and the main seal on the stator side. If you've raised the slide too far it can also cause this to happen, sometimes. As i recall this carb didn't like to idle and had problems with pulling fuel through the choke circuit.

 

[Gardener]

It's a lean problem. Looks to me like your needle is a little lean. Do you have any others, like a DEG to try? I don't know much (read anything) about RMXs, but you look plenty rich on the pilot and at least a half a turn too much out on your air screw. As such, you could also try turning in your air screw a half turn at a time and see what happens. An ideal set-up should have you about 1.5 turns out on your air screw. With that said, at 1.5 turns out on the airscrew, you might have to lean the pilot to a 45 or 48. Do air screw first (free), then pilot (inexpensive), then needle (also relatively inexpensive). This is assuming that there is no air leak.

 

[biglou]

You can spray starting fluid or carb cleaner (I think) around your airboots to check for leaks. If the idle changes when you do this, you have found a leak. I am also leaning towards the lean condition. I know my kTm will surge when I really get her hot with no airflow. Try turning in the airscrew a half turn and see if that gains you anything.

 

[Masu]

OK guys, I'll try all of this in the morning :)

Well in about another 5 hours!

I have abunch on needles and SJs and MJs as Ron gave me a handful, they are hard to come by here in Japan (no kidding)

Cheers!