Jetting one more time 300mxc

Joined
Apr 11, 2001
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#1
I know we have beat this thing to death, and I was about to leave this one un-posted.

I have read many, many postings about this here and on other msg boards but I would like James Deans opinion (and of corse others) on these specs. I have been running these for 6 HSs so far and the power gain at the bottom and mid is just awsome. Most of the PNs that others post here are Honda PNs and I'm not sure what this needle is in honda terms, hope you guys can shed some light.

BYW James Dean was right about the temp thing, with these specs my bike is not as sensitive to changes in temps or alt.

42 pilot
#7 slide
DEG needle, mid clip
172 main

93 oct Exxon
40:1 Maxima Premium 2
temps 30 - 70 deg
Alt 900 - 1300 ft

Very little blubber just off throttle but there is clean power from there up. No more MX feel and there is power in the mid I didn't know was there. This makes it hook up in the mud much better and it is much easer to clutch through the though hills, and rocks.

Plug reads look good, maybe a little lean on the cold days, but no overheating or pinging after warmed up.

RodC
'00 300mxc

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Strick

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Joined
Nov 8, 1999
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#2
1466J

I have found the 1367N (CGH) to be the right needle for my 300. This needle has also performed very well in at least 3 other bikes that I know of, all at different altitudes, and humidity ranges.

James Dean is the king of jetting in my book (PERIOD). I have never become acquainted with anyone who knows more.

There is one area that I do differ greatly from James Dean; jetting for differing altitudes and temperature. We do agree, and James has become quite the crusader, on mixing race fuel with pump gas for ease of jetting and improved performance on KTMs. I used to run 2gal race (110 sunoco - purple) to 3gal pump (92 oct. chevron). I now just run it 50/50 during the race season.

I use Mobil MX2T 40:1, for my premix. It burns clean, and doesn't have a foul smell that makes my 4 stroke friends mad.

I live at high altitude (4500') and ride very high altitudes (up to 9000' regularly)in the hot months. We have 4 seasons here in northern Nevada, especially where temperatures variations are concerned. I rejet my bike every season. I also rejet my bike prior to racing based on weather forecast. I know quite well that I take this jetting this too far. But, my bike always runs as well as it can run. My jetting is never off for more than one ride.

Because I live at higher altitudes than most of the board members, and the fact that we have almost no humidity, it is hard for me to help with spot on jetting, like I can in my neck of the woods. Anyway, there you have my 2 cents. And James if my advice is wrong, feel free to slap me around like a rowdy stepchild! Good LucK

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Strick '99 KTM 300mxc, AMA & BRC member
 
Joined
May 17, 2000
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#3
Rod,

Strick had it right, 1466J = DEG

Our jetting is not too far apart when slide cutaway is factored in. The #7 slide will lean the fuel mixture from low to mid throttle. So 1466J#3 clip/#7 slide would be like 1467J#2/#6 slide. The 14 gives a longer straight section than the 13 by about 1mm (leaner) and you are using a #42 pilot jet(leaner).

It is possible that a 1368J#3 or 1367J#3/#7 slide (CEJ or CEH) would clean up the small blubber you refer to. This will be slightly smoother with less hit to it. Very close though.

My current jetting is:

45 pilot
#6 slide
CEK#4 modified(1369JS with 3rd taper, like a 14xx)
175 main

40% 114 octane w/60% 92 octane
45:1 Spectro
temps 30-70F
alt 0-3500ft (6000ft in summer)

Strick has a leaner clip position by 2 steps but is pretty close otherwise with the 1367N-/#7 slide. The higher altitude would have to figure in.

We may not have the amount of temp and altitude change that Strick has to deal with, allowing our jetting to remain less changed. Usually when I ride higher it goes along with a drop in temperature, making offsetting factors. If not cooler then there are bigger hills to climb and the bike runs hotter, needing conservatively richer jetting.

James

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