not so average jetting?

[hartwill]

Ok I know you guys are tired of jetting questions but this ones a little different. I'm running a stock cylinder with touch up porting, a sparks mx pipe, cr head gasket, 210psi comp, 110 octane 32:1 with benol, and 39mm airstryker with 48 slow, 160 main, and CEL needle. This thing idles all day and performs great at wot, but I was still fouling plugs after about a days worth of riding a lot at mid range. So I moved my needle clip from the middle position to the second from the top to lean out midrange, and after a days riding I ended up with a nice brown plug. Now my question is this, I had a few people tell me to change my main jet instead and leave my clip in the middle position, but I don't want to make a lean spot at wot. what do you guys think? Also I think maybe I could even go up to a 162 or 165 main but that's next weekends project.

[C41Xracer]

I had a similar problem I was using klotz oil then switched to castor927. That fixed my fowling problem

[red88r]

Originally posted by C41Xracer
I had a similar problem I was using klotz oil then switched to castor927. That fixed my fowling problem

How did that fix your fouling problem? Where you mixing it too rich? I have run Klotz products my whole life and never had a issue in any motor.

[hartwill]

Originally posted by red88r
How did that fix your fouling problem? Where you mixing it too rich? I have run Klotz products my whole life and never had a issue in any motor. X2, I think if anything I need a different needle, but I'm not sure what the letters mean and I don't want to lean out the wrong letter if that makes sence..

[C41Xracer]

i fouled plugs alot with klotz and switched brands of oil and it never happened again. it was a suggestion someone gave me and i tried it, it worked for me

[hartwill]

If it keeps fouling I will have to try it.. which klotz were you running?

[C41Xracer]

I dont remember its been a while

[973trx250r87]

ive been running amsoil saber at 44:1 and ive yet to foul a plug with a 72 mm bore pwk39 and cr250 reed cage i forget the jetting

[fearlessfred]

oil fouling should not be an issue with modern day twostroke oils .i think you are on track with the needle changes. at higher rpms,fuel fouling is what your dealing with .keep in mind that oil ratio has an effect on jetting,the more oil the leaner the jetting.

[wilkin250r]

Originally posted by hartwill
, but I don't want to make a lean spot at wot.

Two-stroke carburetors tend to run rich at WOT. Not necessarily because of the throttle position, but because they get richer as the RPMs rise, which is what you're going to get at max throttle position.

Some dirtbikes and old 2-stroke streetbikes had a powerjet to compensate for this, it was an extra jet that would shut off at a certain RPM range to lean out the high RPM jetting.

You could probably go down a size or two on the main and still be okay.

[fearlessfred]

Originally posted by wilkin250r
Two-stroke carburetors tend to run rich at WOT. Not necessarily because of the throttle position, but because they get richer as the RPMs rise, which is what you're going to get at max throttle position.

Some dirtbikes and old 2-stroke streetbikes had a powerjet to compensate for this, it was an extra jet that would shut off at a certain RPM range to lean out the high RPM jetting.

You could probably go down a size or two on the main and still be okay. knowing all of this is great, but trying to compensate for it in your jetting could be a costly mistake. always use plug readings to detemine jetting. in other words,you run it thru a few gears at halve throttle and pull the clutch in and shut the ignition off and coast to a stop and check plug.do the same for wide open throttle,but when leaning out from being to rich on the main dont run it thru all the gears the first time.start at a couple of gears and then checking the plug increasing gears ran thru and checking plug each time.a motors need for less fuel only occurs at the higher rpms.but intill it gets to the upper rpms it still needs the proper amount of fuel.there is plenty of guys on here that can get you in the ballpark for jetting,but you should read the plug along with there advice. there are so many varibales ,that no one person can tell you exactly what you need for jetting. on my own bike, my main can change as much as two sizes from winter to summer