APT SmartCarb

[troffer88]

Exactly ^^^

[Corey]

Originally Posted by arminhammer

Sure wish mine worked well. I have a crap load of time spent on it and it has become a $1000 conversation piece on my work bench.

Thought we agreed to buy it back from you, replace it, or work it out.

[Corey]

Originally Posted by Jakobi

That article shows that they did 4 runs on the PWK, but never mentions if they actually made any changes to improve the running of the PWK. Who's to say their baseline was achieving max power?

When we get ready to do testing like this, we set up the Keihin's for current conditions. We do the tuning primarily based off exhaust temps that we see for that day and peak HP. Idle, mid and top. For yesterday we were 75f. 30.12 in.hg steady and 67% humidity.

Stock 2009 KTM 300 XC

The 38mm ASII was set with a 170 main jet, N3CJ needle 5th clip position, 38 pilot, air screw 1.5 turns out.
The 36mm ASII was set 168 main jet N2ZW needle 4th clip position, 38 pilot, air screw 1.75 turns out. The SC's we used factory settings.

Power valve settings for all tests were; green spring half a turn in.



You will note that the 38mm Keihin builds almost identical power as the 36mm SC on this bike. I've been cautious with posting our own in house dyno charts but theses tests from yesterday show what DirtRider was saying. They also reported they were using KTM recommended settings and listed them in the article.

[Rick]

Last time I checked my pipe does not have a EGT fitting....no dog in this fight for me...yet.....Isn't EGT monitor a advantage?
My buddy runs shifter carts and EGT monitoring plays a pretty vital role in jetting for him.

Please expand on this subject.....
THANKS

Originally Posted by Corey

When we get ready to do testing like this, we set up the Keihin's for current conditions. We do the tuning primarily based off exhaust temps that we see for that day and peak HP. Idle, mid and top. For yesterday we were 75f. 30.12 in.hg steady and 67% humidity.

Stock 2009 KTM 300 XC

The 38mm ASII was set with a 170 main jet, N3CJ needle 5th clip position, 38 pilot, air screw 1.5 turns out.
The 36mm ASII was set 168 main jet N2ZW needle 4th clip position, 38 pilot, air screw 1.75 turns out. The SC's we used factory settings.

Power valve settings for all tests were; green spring half a turn in.



You will note that the 38mm Keihin builds almost identical power as the 36mm SC on this bike. I've been cautious with posting our own in house dyno charts but theses tests from yesterday show what DirtRider was saying. They also reported they were using KTM recommended settings and listed them in the article.

[Jakobi]

Well I put another 150kms or so on mine. Many hours of riding various local terrain. I don't know what it is. I just can't get consistant results. Its like the carb is super sensitive to the bike (or air filter). The start of the ride it was good, very good. A bit in a went one click leaner and rode it like that all day. It ran like a champ most the day like this. Torquey off the bottom, but clean, and then quickly built into a nice crisp pull from mid to top. Then later this afternoon running it home it decides it wants to play burbly bottom end again, still alright torque but likes of 4 stroking and a definite lack in crispness to put it on the pipe. When you'd get it singing it felt like you had to work hard to keep it there too (hard when you're tired). So when I got home, just out of curiosity, I went one click leaner again. Low and behold it cleaned right up and felt good again. *scratches his head*. It was a dry dusty day, but I was either out front leading, or well at the back of the pack when the dust was out. I know the air filter is dirty but I doubt it will be totally caked. Whats up?

[andoman]

The "jetting" changing throughout the day makes me wonder if you have a sticking vent valve (if I understand the design correctly). I. E. you are not getting the air density correction that you should be getting as the conditions change throughout the day.

[drehwurm]

Originally Posted by andoman

The "jetting" changing throughout the day makes me wonder if you have a sticking vent valve (if I understand the design correctly). I. E. you are not getting the air density correction that you should be getting as the conditions change throughout the day.

First it is two valves so both sticking is rather unlikely and second even if they'd stick it would cause a lower pressure within the float bowl meaning a lean condition.

I think I have two possible causes since the "one click leaner" solution doesn't point to float problems.

Unfortunately you have to remove the slide for a check.

1) Look at the flat part of the rod and check if is parallel to the slide surface; additionally try to turn the rod left and right and see how much deviation you can get - it should be very little. I got a faulty D-washer for indexing the rod with my R080 (almost 45? deviation in one direction) and have been making my own D-washers which are milled on the outside and use a set screw for perfect alignment with the rod. A rod that is not close to perfectly aligned will cause differences in fuel metering.

2) Take a flat blade screwdriver and try to operate/turn the clicker mechanism on top of the slide. There should be no free play in the adjuster, but a solid feel against the locking mechanism. If there is free play, vibration can move the adjuster/rod enough to cause fueling inconsistencies. If your mechanism is still working you can try to screw in the small black set screw on top of the adjuster. This should tighten up the free play - if not, it's broken like has been discussed in this thread already.

Have fun :-))

Michael

[Gasgasogeros]

if i see corect the dyno chart of sc give 5hp more from keihin pwk this can have with exhaust very easy doma can add more hp or try tillotson carb with hi end low abjust on the size of carb for easy abjust

[Jakobi]

Michael has the answers, as always! You're the man!

I can tell you right now from memory that there is some definite play in the D washer. Not 45 degrees, but enough that the MR can turn a bit to each side. I know this because I wondered about it when I had the MR out for the lapping. Thought to myself "thats a bit of a sloppy finish". Issue being I don't have access to milling machinery to make up my own. Its very possible it has rotated a bit during running, especially after making an adjustment.

I'll also double check the clicker, but am pretty confident its firm in its engagement from one click to the next. I've already been through all of its parts with it having faint, barely feelable clicks, and poor engagement initially.

For what its worth, the air filter has its fair share of dust caked to it too.

[drehwurm]

Originally Posted by Jakobi

I can tell you right now from memory that there is some definite play in the D washer. Not 45 degrees, but enough that the MR can turn a bit to each side. I know this because I wondered about it when I had the MR out for the lapping. Thought to myself "thats a bit of a sloppy finish". Issue being I don't have access to milling machinery to make up my own. Its very possible it has rotated a bit during running, especially after making an adjustment.

I asked Corey about the acceptable deviation, but never got an answer. If you look at your local (or mailorder) hobby store (for RC planes,cars, ...) you probably find a set collar with just the perfect dimensions - you need 3mm ID/8mm OD (for the R080 rod, A100 is smaller ID) and then have to grind/file the flat part. Do I have your e-mail address? I can mail you a pic of my modified rod with collar.



Michael