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Jetting Frustrations - Little Help Please

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Had this posted in the Jetting Forum, apparently they are too busy to help a brother out, should of just posted it here with my fellow KTM'ers to begin with :lol:

Current Setup:

02 300 MXC, no mods (that I'm aware of)

Carb: PWK 38

PJ: 42

Main: 172

Needle: CEK, #2 clip Pos. (recently changed this out from R-1469-J)

A.S. : 1 1/4-1 1/2

Elevation: 500 to 3500 feet

Temps: low 20's to mid 50's (winter)

Tight gnarlie single track, 1st & 2nd gear mostly.

I want this bike to lift the front wheel when I need it, it will do it in 1st, but 2nd gear it just isn't there, bike sounds like BoooooooWhaaaa.

Before I got the CEK needle I was running a 40 pilot, installed the 42 for the CEK, Thinking about going back to the 40 or maybe dropping down to a 38.

Topend is good, reeds have been checked, clean air filter, powervalve is clean, actuator arm moves when rev'd, power valve adjuster turned all the way out against the case.

Anyone want to chime in with their thoughts?

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I'd drop to a 38.. Have you done a plug chop yet? What's the compression?

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I have never found one magic carb setting that works everywhere at any elevation and every temperature. I rejet my bikes every time I go ride. One week I will be at sea level riding in California and the next week I will be in Nevada riding at 5000' or in the Sierras at 7000'. Sometimes it is 20* out and sometimes it is 110*. I keep a notebook and a log of what worked at every place I ride and what temperature and elevation it was.

The jetting chart in the owners manual is always a good place to start from. You will have to play a little bit depending on things like the gas you use, the oil you use and the ratio that you mix at.

Generally speaking, if it blubbers on the bottom and then hits hard you are fat on the pilot. If you have a lot of spooge you are fat on the pilot. I like to jet lean untill I get a light brown plug then fatten it up just a little. You have to read the plug.

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The later 36 carb. works extremely well in s/t. I made the switch a year ago and never looked back.

Short of that i would go to a 7.0 slide (will need a big pilot jet) the RM needles work very well with the smaller carbs and i imagine they will work just as well with the 38. The OEM N2ZJ in the leaner clip positions is very aggressive. JD blue,7.0 slide works well all so.

At some point this winter i will try the RM needles in a 38 and a 39 just to see how it runs. (not a priority so it may be a while)

Keep the powervalve screwed in....to far out and it just kills torque/snap off the bottom.

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Compression is 195, slide is a 6.5, haven't done a plug chop since I installed the CEK needle, with the old needle the plug was light brown.

I played around with it again today, swapped out the 42 with a 38, clip in 2nd groove, made no difference, moved the clip up one, same response, moved it to 3rd, 4th and 5th, same response, throttle response is slow in 2nd gear, acts like it's winding up then finally comes into the power band.

Changed out the 38 with a 40 and started playing with the clip position again, felt the same as before, booooWhaaaa made no difference where I put the clip so I said screw it and put in the original needle (R-1469-J) clip in 2nd position with air screw turned down to 1/4 out, much better response in 2nd gear, whacking the throttle I can feel the front end getting light, still not where I want it but better then with the CEK needle installed.

Wondering if the CEK needle is not really a CEK but something different?? I don't have a selection of needle so I can't try something else and this close to Christmas my wife would kill me if I bought a bunch of different needles to play around with.

Kind of leaning towards buying a JD kit after the holidays, James said he will ensure I am satisfied with his kit.

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Something is wrong.

Drastic pilot and clip position changes and no difference ?

There was some change, change for the worse, bog was more pronounced and bike took longer to get into the power

Where is your power valve adjusted at? I usually keep my screw flush with the housing.

Little Jeff

That's were I run it also, screw full turned out.

I've gone back to stock needle and 40 pilot, response is better, not where I want it but better.

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Ok, just maybe the CDI is messing up.. or the coil. If you have a friend with the same CDI I'd try swapping it.

On another note the slow response might indicate that the PV is not opening properly.. Or you may have an exhaust restriction. Just throwin some ideas out there..

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My local bike shop is closed tomorrow, I'll give them a call on Tuesday and see what the R-1466-N needle goes for and how long it will take them to get it.

I don't think it's the CDI or coil as the bike starts and runs fine when on the pipe, just sluggish on the bottom end.

I'll probably open up the topend after the 1st of the year just to take a look.

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Here, you can cross reference the R needle to the Sudco. Hopefully, it will help you figure out what affect the changes are/should have.

http://www.sudco.com/vol33/135-136.pdf

Appears the R1469J needle is the same as the DEK, which is just a different taper than the CEK you are trying to run. Shouldn't have to make many changes to make it work.

The 1466 will be richer off idle than the 1469. The 66 and 69 refer to the starting diameter.

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Does it still have the stock intake and reeds? A Rad Valve or V-Force make a huge difference over the old stock intake. Is the power valve timed right? Are the dots on the gears lined up? Put the red power valve spring in. Just some other thoughts besides jetting. The R1466N sounds like a good idea. I used to use a R1468N but thats no longer available from Honda.

Edited by ktmfred300

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Here is my guess.. Take it from a guy who has done a lot of riding at the temps you are talking about. Jetting at those temps is an excersise in futility, there are other factors going on... All it takes is just a tiny bit of moisture in the air and you start getting carb ice... There is NO way to "jet" under these conditions. SORRY. Just go back to your summer jetting, make a rough guess at richening it up if you wish, but don't bother trying to fine tune it, can't be done... Unless, you buy a carb heater.

Cheers

Edited by 7thirtyseven
Changed "fine time" to "fine tune" damn auto correct...

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Does it still have the stock intake and reeds? A Rad Valve or V-Force make a huge difference over the old stock intake. Is the power valve timed right? Are the dots on the gears lined up? Put the red power valve spring in. Just some other thoughts besides jetting. The R1466N sounds like a good idea. I used to use a R1468N but thats no longer available from Honda.

I'm running the V-3 reeds on it, I haven't opened the power valve since I've owned it (just over 1 year) but the valve and linkage is responsive to the throttle, funny you mention the timing, I checked it this weekend when I was working on it, as I was wondering is it was possible for it to slip out of alignment, they're all lined up and I see someone has done the weld mod.

Here is my guess.. Take it from a guy who has done a lot of riding at the temps you are talking about. Jetting at those temps is an excersise in futility, there are other factors going on... All it takes is just a tiny bit of moisture in the air and you start getting carb ice... There is NO way to "jet" under these conditions. SORRY. Just go back to your summer jetting, make a rough guess at richening it up if you wish, but don't bother trying to fine time it, can't be done... Unless, you buy a carb heater.

Cheers

Interesting concept, hadn't thought about carb icing, did you notice the icing on the outside or the inside? I went back to the stock needle with the 40 pilot, bike is running better with this setup, at least now I can feel the front end getting light when I whack the throttle.

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The carb icing that will effect you is , of course on the inside. You will often get stuff freezing on the outside but that doesn't effect performance at all. I could blab on more, but suffice it to say, it is a huge issue if you are trying to jet at low temps.

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That bog you mention almost sounds like a lean bog off idle. When my bike is rich in the pilot/needle it tends to miss. If it's too lean it'll bog.

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Wow....this thread is going all over the place. lean,rich, higher,lower......sheesh. one last stab.....my 09 came new with a float level way too high. it not only would dribble if leaned a tad more than kickstand angle, but would stumble at 1/8 to 1/4 throttle. how is your float level? by the way....listen to ktmfred as he is the resident KTM expert in WA as he was in the industry here for over 30 yrs.:bonk:

Joe

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