Anyone running a 160 main?

D

duke

Member

Oct 9, 1999

484

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• Jul 17, 2004

• #1

In removing the carb for some cleaning and inspection, I noted its previous owner had installed the following: 160 main, 48 pilot and R1173L needle, set at the 2nd clip position. This may explain the slightly "rich" characteristics in engine perfomance and excessive smoking. OH, BTW, the engine has air box lid removed, after market air cleaner and PC Rev pipe and S/A. I am thinking of simply going across the board with those base jetting recommendations for 200's that feature Stage II tuning mods: 155 main, 45 pilot and R1174K needle. Or should I adhere to the adage where one shouldn't make more then one jetting component change at a time?

Bill

 

KelvinKDX

LIFETIME SPONSOR

Aug 25, 2000

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• Jul 17, 2004

• #2

What you want to do is probably a good starting point. From there i would spend the time to jet it correctly.

 

D

duke

Member

Oct 9, 1999

484

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• Jul 21, 2004

• Thread starter
• #3

In regards to the rich jetting, I changed the oil/ratio a bit, and re-packed the silencer thus resulting in the overly rich characteristics going away: Less smoke after warm up and a slightly crisper throttle response. A fresh plug shows the resistor as being a light coco brown; in essence the "ideal" color. As for the aforementioned jetting specs consisting of 160 main and 48 pilot, I have since found out that those are stock specs. Pro Circuit recommends that in the use of their pipe and S/A, that the owner maintain stock jeting specs. I wonder why this differs from FMF's recommendations for a 155 main and 45 pilot?

 

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Nice Guy Eddie

Uhhh...

Jun 30, 2004

140

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• Jul 21, 2004

• #4

I droped from a 160 to a 155 and noticed a difference (I have a stock pipe and run 32:1)... it still runs rich (500' elevation).... but no where near as bad as stock.... the bike has more pep and obviously burns cleaner... I intend to refine leaner from here when I have more time to do it right....

Unless you are in a realy dense air situation (sea level in the cold) I think a 155 should be plenty safe)... you should still check it just in case.. if in doubt, go a little rich... you'll still be happy with the changes...

 

D

duke

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Oct 9, 1999

484

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• Jul 21, 2004

• Thread starter
• #5

Eddie

Have you retianed the standard pilot and needle?

Bill

 

N

Nice Guy Eddie

Uhhh...

Jun 30, 2004

140

0

• Jul 21, 2004

• #6

no and yes... in that order.... I think the pilot is a 42?... I'd want to check to be sure though before telling you it's safe....

I wont have it apart again until a week from now or so.... (thats when I intend on leaning her a bit more).... if you still need the input then, I will let you know what it is.. (but I know I leaned it out from stock)

 

J

Jim Crenca

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Mar 18, 2001

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• Jul 21, 2004

• #7

What year is bike. Older KDX's (like my 94) have been know to need a big main for proper jetting. IMO the way to realy check WOT jetting is to hold bike wide open in 5th or 6th gear under a slight load (gentle grade), and after approx 15 seconds kill engine with throttle open while pulling in clutch, Next remove plug and cut off threaded area to look at insulator, there should be a thin dark ring, Lots of good threads on this in Adv. Tech. Pay no attention to what your friend's jetting is, jet your bike for elevation, barometric press, altitude, fuel, etc.

 

D

duke

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Oct 9, 1999

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• Jul 22, 2004

• Thread starter
• #8

Its a 99 KDX200

 

J

Jim Crenca

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Mar 18, 2001

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• Jul 22, 2004

• #9

Don't remember 99's having a big main jet issue.
I'm assuming you checked for any air leaks in the intake system.
Also, when you mention a tan colored plug, is this from removal after normal use, or is it from a WOT plug chop?

 

D

duke

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Oct 9, 1999

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• Jul 22, 2004

• Thread starter
• #10

I have yet to conduct a WOT test. The plug color was the result of trail riding only; I realize that that doesn't serve serve as an accurate indicator. I am about to purchase some Boyesen power reeds. Boyesen recommends deviating from stock jetting specs by stepping down one size on the main jet only. The only reason I brought this matter up, is that it seems everyone has installed smaller jets across across the board on their bikes, regardless if the machines are left completely stock or extensively modified. I am content with the power, but like so many I am always seeking more if there is no effect to durability. I also realize that there are many other factors left out of the equation which determines proper jetting such as climate, barometer reading, etc..and of course terrain. Lots of steep hills and sand tax a motor and a little rich under these conditions would be more prudent.

Bill

Duke

 

J

Jim Crenca

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Mar 18, 2001

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• Jul 23, 2004

• #11

I applaud your efforts for seeking better performance but don't recomend using trail riding as any indication of jetting accuracy in regards to plug color. There have been other KDX riders who have used general riding tan plug color as an affirmation for propoer jetting only to seize the motor due to lean conditions during extended high RPM riding. I do agree that most with later modle KDX's are using a smaller main. I had Boysen power reeds but change to Moto Tassinari V Force II and like them more. Please post back when you have a chance for a WOT chop.

 

D

duke

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Oct 9, 1999

484

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• Jul 23, 2004

• Thread starter
• #12

I plan on doing just that. However, my trail riding generally finds me pinning the bike for a long time in order to traverse long sand washes and the steep hills found here in the desert. But again I acknowledge that even given these conditions, an accurate jetting assesment cant be made. I will return after having performed the WOT test. Thanks all

Bill