High-altitude Jetting results - Colorado



55 replies to this topic
  • LarryCO

Posted May 01, 2002 - 05:13 AM

#41

Racemile,
Go buy an EKP needle jet (pn# ...-14916-EP) from yamaha. Put that in on clip position #3 (3rd down from the top). Make sure your pilot air jet/screw is set to 65 (good combo with a 38PJ). Remember that it's not just the PJ/PAJ that affects down-low...it's also the diameter of the needle jet (in your case, you want a "P" with a 38PJ/65PAJ combo).

Get rid of that stock needle and replace. You'll be very happy (best $15 spent)...

What is your "stock needle" anyway? DRR?

While you're buying jets at the dealership, the only other thing to do would be to buy a 160 main air jet...but that will only help out on the top end (wont solve your problem). Once you get things sorted out down low, you'll definitely be wanting this jet!

Finally, the only other mod you NEED to make is the BK mod. Cures up that "dead spot" when blipping the throttle (way too much gas being squirted in). HUGE improvement...do it if you havent already. Do searches on "BK mod"...there's even parts lists from Home Depot and pictures!

Larry

  • Taffy

Posted May 01, 2002 - 07:03 AM

#42

larry i can't agree with the above and let me tell you why...

i think (in many ways rightly) you've picked your info up from previous posts but the cart is infront of the horse.

somebody somewhere has an EKP needle and we offered help to get a pilot to suit WITHOUT swapping the needle out.

but starting with a fresh sheet as they say; it's EMM or EMN needle all the way and DUMP that EKP.

the PC for the EMM and EMN is 45PAJ/35PJ.

i tested and tested that EKP and it IS the bog. don't blame the APJ it's the needle.

apologies larry.

Taffy

  • LarryCO

Posted May 01, 2002 - 09:05 PM

#43

Taffy,
No worries...you're the one who's steered me thus far. I just know that I dont have any of his "symptoms" when I rode last weekend here locally or out in Moab the weekend before last using the 38PJ/65PAJ/EKP#3 combo...which turned out to be great! I DO have the BK mod done, which I found was a HUGE help. Perhaps this is his problem...

I thought that the 35PJ/EKN#3 was about as far as I could go (given our altitude difference), but I suppose we could try a 35PJ/EMM#3 and see what happens (1/8 throttle might be too rich). Great, one MORE test to do before I'm satisfied... :)

Late

  • Taffy

Posted May 01, 2002 - 01:58 PM

#44

far too much is made of this altitude thing.

think about it. 24 months ago when i joined everyone was suggesting or running 178/180MJ with a 48PJ. every other post was about fouled plugs...

now the bikes pretty much survived that "rich" spell didn't they!

so now we're all getting down to 160MJ which is a drop of i don't know what!!!

er! lots :) :D

so when hank who now runs a 160MJ and is delighted goes up in to the stratosphere at 4-6,000 feet, is he going to have a greek tragedy on his hands. i hope not anyway.

i think when all you boys settle down your going to find your jetting a delight. at every altitude.

i've said it before that if you feel that you're rich or lean as the seasons change and you move by 2 or 3 on the MJ it should give you a MJ that will work for all 12 months of the year.

for instance if you feel a bit vibby on top this spring and you go from 160 to 162 and it sharpens it up nicely you'll find that next autumn your 162 will be right/slightly but unnoticeably)lean.

a jet for all seasons.

i get the feeling a lot of riders are going to go silly this spring. i just get that feeling. you know, "i know what i'm doing now". like i say one jet up or down will do it.

and don't forget i'm still the only one who says you jet up in the summer. i'm on my own (where i like to be). watch that old weather chart as big bazookas says "here comes another high pressure with some beautiful sunshine".

anyway, all good fun as they say. what did i do before i found this bloody web site anyway :D :D

Taffy

[ May 01, 2002: Message edited by: Taffy ]

  • racemile

Posted May 03, 2002 - 04:25 AM

#45

Wicked, Larry, Taffy;

I am there (almost).

The final set up is:
PAS 1 3/4 turns out
PJ 40
MJ 158
Stock needle on pos 2
All other variables are stock 2002 settings.
gray wire has been cut.
bk mod NOT done

The bike will launch and pull the front wheel easily (unexpectedly the first time LOL) I still have a TINY bit of stutter/stumble to about 3/4 throttle. At this point I dont know if the engine stops pulling due to jetting or rev limiter. Its feels like I moved the power from the last 1/3 of the throttle to the first 3/4 of the throttle. I will ride some this weekend to really test this out but, the around the block test blew me away.

The fix:
I am thinking about position 3 on the needle. Any feedback?

Thanks for your help guys.

  • Wicked_Crash

Posted May 03, 2002 - 06:17 PM

#46

racemile,

When you say you have the needle on position 2, do you mean two from the top, or two from the bottom. I have my needle set at the 5th position from the bottom. When you have a stumble at 3/4 throttle, it could be the needle position or the main jet. If your problem is at wide open throttle, I would say it is the needle position. You might want to take it for a good ride before you change anything else, but if after you do so and it still behaves the same, I would drop the main jet a little more. Isn't jetting fun! Thanks for the info on the Last Chance Enduro by the way. It looks like I wont be able to go after all, but I am heading up to Woodland Park again tomorrow. :)

  • Taffy

Posted May 03, 2002 - 11:09 PM

#47

you must count the needle clip position from the top.

official.

Taffy

  • racemile

Posted May 06, 2002 - 12:18 PM

#48

Larry, Wicked, Taffy:

Went out this morning. The power rolls on smmmooooottthhhh. When you kick it hard it will boil the backtire in third, (probably fourth and fifth too, but, I didnt get that far where I was riding) all you have to do is roll the throttle. I am very satisfied with this setup. I will try dropping the clip into position 3 (third down from the top), But, I am VERY happy with this setup. I can't thank you guys enough. :D :) :D :D


Thanks
Jason

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  • LarryCO

Posted May 28, 2002 - 08:46 AM

#49

Another jetting update:

5/27 Moab, UT (4K - 5K ft...85F):
35PJ/50PAJ/1 turns/EKN#3/150MJ/160MAJ
('01, WR timing, uncorked US exhaust, BK mod)
-Bike started cold first kick every time with choke. Occasionally started first kick warm (no choke or hotstart)...sometimes required hotstart. Idled a bit rough...but not bad.
- Low end bog/hesitation when whacking the throttle open (to wheelie something). Fairly smooth acceleration upon gradual twist of throttle.
- Great accel from 1/4, 1/2, and 3/4 throttle.
- Excellent high-end performance at max torque and max revs.
- Very little backfiring upon decel. at high revs and 1/4 and 0 throttle.

Overall: Too rich at 0 - 1/4 throttle. Going to an EMM needle will just make the situation worse.

Thus, I believe I'll conclude my jetting experimentation (with the E series needles) by stating that the best setup for my bike here in CO (Rampart Range, Moab, etc. from 4K - 10K ft.) in the summer is 38PJ/65PAJ/1.5 turns/EKP#3/150MJ/160MAJ. I'll be switching it back tomorrow and running with it. Of course, there's more work to do when above 10K ft...but I'll figure that out in Crested Butte over July 4th...

Late

[ May 28, 2002: Message edited by: LarryCO ]

  • Wicked_Crash

Posted May 28, 2002 - 11:46 AM

#50

Hey Larry,
How was the ride at Moab? My Dad and a buddy of mine went to Texas Creek on Sunday, had a good time. My dad started to get tired so he headed back to the truck while my buddy and I checked out another trail. Turns out that on his way back to the truck, he about ran into an 8' tall bear in the middle of the road! He got his bike stopped sideways about 30 feet away from the bear and kept reving the engine to try to scare it away (and to try to get away in case the bear charged) while they were staring at eachother. The bear finally wandered up the hill after about 5 minutes. Pretty exciting to say the least! Hope you had fun. :)

  • LarryCO

Posted June 24, 2002 - 07:14 AM

#51

Another jetting update:
6/21 St. Mary's Glacier, CO (9500 - 12K ft...70F):
38PJ/65PAJ/1 turn/EKP#3/150MJ/160MAJ
('01, WR timing, uncorked US exhaust, BK mod)
-Bike occasionally started cold first kick with choke. Occasionally started first kick warm (no choke or hotstart)...at higher altitudes (12K), ALWAYS required hotstart. Idled rough.
- Low end bog/hesitation when whacking the throttle open (to wheelie something). Acceleration rough upon gradual twist of throttle.
- Slightly rough accel from 1/4, 1/2, and 3/4 throttle.
- Barely adequate high-end performance at max torque and max revs.
- Extreme backfiring upon decel. at high revs and 1/4 and 0 throttle.
- Fouled new iridium plug at 12K ft after riding for 2 hrs.

Overall: WAY too rich at 0 - 3/4 throttle. EKP needle too rich from 0 - 1/4 throttle and clip position #3 also way too rich. VERY BAD CHOICE FOR HIGH ALTITUDE RIDING (10000 ft. plut).

  • LarryCO

Posted June 24, 2002 - 07:21 AM

#52

Another jetting update:
6/23 St. Mary's Glacier, CO (9500 - 12K ft...75F):
38PJ/65PAJ/1 turn/EKQ#2/148MJ/160MAJ
('01, WR timing, uncorked US exhaust, BK mod)
-Bike started cold first kick with choke. Occasionally started first kick warm (no choke or hotstart)...at higher altitudes (12K), frequently required hotstart. Idled slightly rough.
- At higher elevations (11K ft plus): Low end bog/hesitation when whacking the throttle open (to wheelie something). Acceleration slightly rough upon gradual twist of throttle.
- Good accel from 1/4, 1/2, and 3/4 throttle.
- Good high-end performance at max torque and max revs.
- No backfiring upon decel. at high revs and 1/4 and 0 throttle.

Overall: EKQ needle with 38PJ/65PAJ OK choice. Still slightly rich on pilot circuit...will try 75PAJ next ride over 10K ft. EKQ clip position #2 MUCH BETTER choice at higher elevations (anything over 10K ft - Crested Butte, St. Marys, etc.). ADEQUATE CHOICE FOR HIGH ALTITUDE RIDING (10000 ft. plus).

  • Taffy

Posted June 24, 2002 - 02:13 PM

#53

HOW ABOUT KEEPING THAT pas AT #65 AND TRYING THE 35PJ? that may work better at low revs.

go down again on the MJ.

i had a rider PM me about a month ago and asked for help from the DR side. he said "what MJ did i recommend out of 140 or 142?".

i thought that he was having me on. after all nothing has been said here and i can't replicate 10,000 feet while sitting 25 feet below sea level here in the fens of anglia. "oh no" he said, my friends are lower than that!

apparently one of them is down to 135MJ.

this Larry means that you could be the first over here to find out so lower that MJ and start ALL OVER AGAIN!

Taffy

  • LarryCO

Posted June 27, 2002 - 06:17 AM

#54

Another jetting update:
6/26 St. Mary's Glacier, CO (9500 - 12K ft...65F):
35PJ/60PAJ/1 turn/EKQ#2/148MJ/160MAJ
('01, WR timing, uncorked US exhaust, BK mod)
-Bike started cold first kick with choke. Always started first kick warm (no choke or hotstart)...at higher altitudes (12K), rarely required hotstart. Idled very slightly rough.
- At higher elevations (11K ft plus): Occasional low end bog/hesitation when whacking the throttle open (to wheelie something). Acceleration good upon gradual twist of throttle.
- Good accel from 1/4, 1/2, and 3/4 throttle.
- Good high-end performance at max torque and max revs.
- No backfiring upon decel. at high revs and 1/4 and 0 throttle.
Overall: EKQ needle with 35PJ/60PAJ best choice yet for higher elevations. Still very slightly rich on pilot circuit...will try 65PAJ next ride over 10K ft.

  • LarryCO

Posted September 11, 2002 - 12:02 PM

#55

Another jetting update:
9/10 Crested Butte, CO (9500 - 12K ft...60F):
38PJ/65PAJ/1 turn/EKQ#2.5/150MJ/160MAJ
('01, WR timing, uncorked US exhaust, BK mod)

- Bike started cold first kick with choke. Always started first kick warm (no choke or hotstart)...at higher altitudes (12K), mostly required hotstart. Idled well.
- No bog anymore at low throttle ranges (solved problem by raising clip 1/2 position). Not quite as snappy as could be but decent (below 3/8 throttle).
- OK accel at 3/8 or 1/2 throttle...slight bog...after 4 days of altitude, started to really bog down and foul plug.
- Below average at 3/4 to full throttle. Took too long to achieve rev limiter. (Slightly rich)
- No backfiring upon decel. at high revs and 1/4 and 0 throttle.

Overall: Pretty rich on pilot circuit from 3/8 to 1/2 throttle...and slightly rich over 1/2 throttle. Will try same setup (38PJ/65PAJ/EKQ#2.5/150MJ/160MAJ) with a 145MJ instead to lean 3/8 throttle occasional bog and lean out the top end. Expect this new setup to perform very well!

Subsequent test: 35PJ/50PAJ/EKQ#2.5/145MJ/160MAJ...to improve snappiness of low end.

  • James_Dean

Posted September 13, 2002 - 02:22 PM

#56

***This is a '02 KTM 400EXC jetting result, but still in your high altitude riding area & may be of interest-

9/3-9/7 riding in Crested Butte and Ouray areas from 8000-13000 ft elevation

Start-
#42 pilot/#85PAJ/1 turn/DVQ#4/#165MJ/#200MAJ-
Started perfect, had rich hesitation at 1/4-1/2 throttle, revved out good up to ~12000ft

Revised day 2- fuel screw & clip position
#42 pilot/#85PAJ/3/4 turn/DVQ#3/#165MJ/#200MAJ-
Started perfect, clean running throughout the throttle range, more crisp feeling, excellent fuel economy, top end strong 8000-12000ft

Day 5 observation @13000ft (??) to top of American Flag pk.-
Low throttle range ran very good still.
Full throttle was running rich (165MJ/200MAJ/Dxx needle) climbing fast WOT near the top of this peak. Sputtered badly and had to back off to keep it running. The air filter was on the second day of riding and may have needed cleaning, but it was marginal rich jetting here. A #158-160 main jet was needed for 12000ft+ elevation WOT while running a Dxx needle. I would think an Exx needle would need ~#150 MJ/200MAJ to pull this altitude.

Future setting above 8000ft expect-
#42 pilot/#85PAJ/3/4 turn/DVQ#3/#160MJ/#200MAJ
(could go to #40 pilot, but it started & idled perfect)

Hope this is useful for comparison.

James




 
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