KTM 300 jetting

 I'm at my wit's end.  My '06 300 XC-W is jetted toward the lean end of what
I'm seeing other riders recommend.  The dealer tells me that his customers
seldom have plug fouling problems, even when running way too lean.  I'm
running a 152 main, 35 pilot, and N8RG needle set on the second groove from
the top.  Plugs foul every 50-100 miles.  They are a dark sooty black.  The
last one fouled after a long downhill run, leading me to believe I'm running
rich on the lower speed circuits.

OTOH, what are the chances of a power valve, bad rings, crank seal, or
something else causing this problem?  I just replaced the coil, thinking
that was the cause of the problem.

Thoughts?

I've had a Wiseco piston backordered for 6 months, or I'd be checking out
the top end during a freshen-up to rule out other problems.  Until then, I'm
hesitant to spend too much time messing with jetting.  I'm inclined to just
carry a bunch of plugs with me for the time being.

-Jeff-

 On Mon, 16 Jun 2008 22:43:25 -0600, "HellSickle"


I am the absolute last person to offer any authoritative jetting
advice and it baffles the shit out of me.  Not sure if you have
the owner's manual for that and I'll be happy to e-mail it to you
in .pdf format if you'd like it, but on Appendix Page 10, it shows
(and I'm guessing at your altitude and current temps):
5000-7500 feet, 79-98 degrees
Air screw - 1.5 turns out
35 pilot
158 main
NBRW needle
clip in position 2

The N8RG is a somewhat richer needle.

What oil and ratio are you mixing?  My son's 200 was fouling plugs
about as frequently as you are when running Mobil 1 at 50:1.  When
that got hard to find, I switched to Amsoil Dominator at the same
ratio and didn't touch the jetting.  It has not fouled a single
plug in 6 or 8 months.


Silencer packing?


It's also been suggested to me that I skip Wiseco top end parts
and go with strictly OEM.




----
Team NCS Off Road
----

 

I've already got the .pdf manual for '06.  Nonetheless, thanks for putting
me in "mail jail" with a 5M email. :-)


It is the leaner of the two needles that came with it.  The next step leaner
is N8RH.  I was also fouling in Utah, where I was running a bit leaner than
what the jetting chart would indicate.


I'm running Honda HP1, 40:1.  Same thing I've run in the ATK for years with
no problem.


Recently done.


I'm in agreement.  KTM has the piston in stock.   Quite a bit more $$ tho.

-Jeff-

 wrote:


Ooops.  Well, now you've got the newer, mo' better one...


Have you talked with Jay C. about it yet?


Is that a full synthetic?  Just curious.


But it'll last that much longer...

 

I've used a couple of Wiseco pistons in my 300 and they were okay. I
thought that they had a little more vibration and my theory is because
they are lighter? They may (probably) not last as long as oem?