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Jetting can be Fun

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Posted by: White_Knuckles---------------------

Okay, time to reach out to you wizards of jetting. I'm trying to dial in a new carb on a 2000, 200. Reading all I can find I ordered this config from sudco. 35mm PWK, 42 P, 155 M, R 1174K needle per CND Dave's recommended start point for a 35 Gnarly no airbox lid.

This seems like the proper range for a start. Altitude is 3500 ft air temp 75. The result is smooth idle and it runs great throughout the range. The questions include the air screw is set where at operating temp the idle runs highest. This is about 1/4 to 1/2 out. That would seem to suggest too small of a pilot but it runs fine. The second concern is with the angle of the Turbo silencer it always forms the dreaded spooge line that drips a few drops on the swingarm. It runs so well I wonder as I continue if you can solve for spooge by jetting or maybe trying other oil tweaks first. At 36:1 silkolene maybe switching to the magic Mobile MX2T should be a starting point before the brass. Help me brothers.


Posted by: dsndblm---------------------

From my limited experience, here is my 2 cents worth........

The setup that you described is a "recommended starting point" its just that, a starting point. Read Daves section on checking the plug at different throttle ranges and make changes as required. I agree with the theory of starting with the main and working your way down. Main jet, needles and clip position, pilot/airscrew. Too big on the main caused other circuits on my 88 to be effected also

I had my carb off or apart so many times I lost track before I got it right. I have zero spooge and a nice running bike. Keep at it, be patient and look at the plug.


Posted by: G. Gearloose---------------------

AS --> (Highest Idle) = (dull off idle)^2 / (under load)

You did all that and havn't metioned the clip yet....

The pipe will blow spooge until you flush it, don't jet by spooge.


Posted by: 91kx---------------------

Can the stock 91kdx silencer/sparky be repacked like an mx silencer would be?


Posted by: wanaride---------------------

Mobil MX2T helps the smoking situation but hasn't helped me in the spooge dept, I still get a black gooey line down the bottom of my S/A even when I'm on the pipe. Granted, I probably need to repack it, but with 50:1 MX2T I'm still spoogin'...

Jetting: M=152, P=42, stock needle with clip 2nd notch from top, AS=1 turn out, snorkel removed, BR8EG plug.

My hope is that the spooge I'm seeing is the residue from my richer jetting days, and that spooge will be minimal after the S/A repack, but I'll have to wait and see how that goes.


Posted by: White_Knuckles---------------------

Quote:
Originally Posted by G. Gearloose
AS --> (Highest Idle) = (dull off idle)^2 / (under load)

You did all that and havn't metioned the clip yet....

The pipe will blow spooge until you flush it, don't jet by spooge.


Gearloose, I think I understand your formula. Are you sugesting to back out the air screw as highest idle =dull off idlle response? Idle drops as I back it out. Somewhere I read highest idle with the airscrew is the optimum setting.

Clip is in center position, going to raise it one step to lean 1/4 throttle slightly. "Don't jet by spooge" solid info, I have not repacked for current tests. Thanks.


Posted by: G. Gearloose---------------------

Its optimum if you get off on stoicometric perfection, but most of us get off on having firm power right off idle, and that also equates to stall resistance, and a few other goodies.
Best throttle responce is typically with the AS In, (read richer) side of the highest idle position. This can only be evaluated under load, snapping the throttle in neutral is not equivelent.

In second gear and idleing up a slight incline, bring the revs down really low and roll the throttle up to 1/8 throttle and back to idle. Use the same incline and speeds and try different AS positions, move it just a little at a time, until you find its optimal position, then you will be very happy.

The highest idle position thing is simply to roughly evauate your selection of pilot jet.


Posted by: White_Knuckles---------------------

G. Gear..and other helpful posters,

Right, the text did not suggest more than ranging the pilot. I thought highest idle was where the engine responded under the most efficient setting. Thanks for the clarification, will use real world testing as suggested.

The spooge factor is a reminder that I may be too rich on the main. With all the jetting info here some have completly eliminated pipe drool where others have it continue. I question the silencer designs maybe some trap unburned oil better. More tests are in order. Love that "Zen" tinkering.

Stoichiometric Combustion: Stoichiometric or Theoretical Combustion is the ideal combustion process during which a fuel is burned completely. ...



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