Still not perfect

[skinnybob]

Time to ask for some more help. 09 klx450,full fmf q4, snorkel, ais removed, jd jet kit. live in colorado, usually ride 6-10000 ft.

current settings are:

main 160

pilot 45

red needle 3rd from top

flex jet fuel screw 2 turns out.

I'm alot closer than i was when i got the bike, but still not perfect. still runs right on the edge of overheating, but hasn't, wack the throttle, has a slight bog, and can't seem to get rid of the hanging idle when i stop, without playing with the clutch. also getting decel pop, and seems like alot of carbon at the end of the exhaust can.

Any suggestions, would be greatly appreciated, i mostly ride trail, with slower riders (my wife and son)

[skinnybob]

bump 1

[kalvin22]

decel pop usually means lean on the pilot. you may be able to cure it by backing out the fuel screw a little bit. hanging idle also suggests a pilot problem (clogged partially). if you are running hot that also is a sign of being lean.

if it were me I would solve the hanging idle first. if it is a clogged pilot the easiest is to just replace it, plus they are fairly cheap. depending on how plugged it is, that could be contributing to the decel pop as well.

Edited August 24, 2010 by kalvin22

[William1]

Set the fuekl screw according to the accepted procedure and leave it alone. Reduce the idle speed a tiny amount.

Turn the AP tming screw CCW 1/2 turn.

160 main is too large

a 4,000' range is a bit much to expect the carb to deal with. I'd aim for perfect jetting at the 6,000' mark and be happy.

[skinnybob]

The current settings including the 160 main is per the sheet that came with the jd jet kit, the dealer had a 48 pilot in it, returned pilot to stock which is the 45.

I tried to set the fuel screw per the info i found on here, and two out is where it seemed to be pretty smooth idle.

[skinnybob]

Set the fuekl screw according to the accepted procedure and leave it alone. Reduce the idle speed a tiny amount.

Turn the AP tming screw CCW 1/2 turn.

160 main is too large

a 4,000' range is a bit much to expect the carb to deal with. I'd aim for perfect jetting at the 6,000' mark and be happy.

just out of curiosity, what will be achieved by turning out the AP screw? And i had a feeling that the 160 was to large, was thinking of trying the 155, and what about the needle setting?

Edited August 24, 2010 by skinnybob

[William1]

Lets take each hing one at a time. First, a little logic. When setting a bike up, get the base jetting right. That means the pilot/fuel screw:

Fuel screw settings in the 'book' are recommended starting points. Every bike is different, as is the temp and altitude. Set the screw according to this method. Do it with the bike fully heated up.

Gently turn the screw all the way in. Now back it out two turns. Start the bike and fully warm it up, go for a 10 minute ride. Set the idle to speed to 1,500~1,800 RPM as best you can (I know, without a tach this is tough, just set it to were it idles relatively smoothly). Once warmed, slow the idle to the lowest possible speed.

*** When turning the fuel screw, keep an accurate 'count' of the amount you are turning it and record it in case you have to reset it for some reason. Makes life easier when you can just set it from notes Vs. going through the procedure again.***

Turn the screw in until the idle becomes rough or the bike stalls.

if it stalled, open the screw about 1/4 more turn. Restart it and slowly screw it in till you can just perceive a change.

If the screw can be turned all the way in and the bike still idles perfectly and does not stall, then you need to go down a size in pilot jet.

Now very slowly, open the fuel screw till the idle is smooth. Blip the throttle, let the bike return to an idle, wait say ten seconds. Confirm it is the same smooth idle.

If the screw has to be opened more than 3 turns to get a smooth idle, you need to go up a size in pilot jet.

If you find it does not stall with the larger jet but has to be open more than three turns with the smaller pilot jet, put the larger one in and set the fuel screw at 1/2 turn.

If the idle speed increased, adjust the idle speed knob to return the bike to a real slow idle speed. You must then re-visit the fuel screw. Keep doing this till the fuel screw is opened just enough to provide a nice steady idle at the lowest possible RPM. Once this is done, increase the idle speed to the normal one for your bike, typically about 1,800 rpm, but go by the spec in your manual.

Then the main jet:

Starting with the recommended main, remove the airbox door and go for a ride (bike fully warmed up). Is it better or worse?

If it is better, you need a smaller main.

Go down one size, replace the airbox door, ride. Remove the airbox door and test again. Better or worse? If better, go down a size again. Keep repeating this till the test with the airbox door is worse.

If it was worse with the airbox door removed, tape over 1/3 of your airbox opening, test (airbox door on, of course).

If it is worse now with the tape and was worse with the airbox door off, your main is just right. You are done!

If it seems better, you need to go up a size in main jet. Then test it again (remove the tape). Replace the tape, test again. If with the tape on it is better, go up another size in main. Keep repeating this till having the tape on is worse than with it off.

To finish up and ensure you are set accurately, retest the bike with the tape off (airbox door on), ride it, then remove the airbox door (tape off, of course). Best performance should be with the airbox untapped, airbox door on.

Remember, the main only operates at WOT. Ideally, you want to be in 3rd or 4th gear doing the tests, hitting max revs (just shy of the limiter) for at least 10 seconds to get an accurate representation of the jet status.

Then the needle. The needle is more tricky as it covers a wide range. Foirtunately, JD has done 90% of the work already. All you need to dom is be concerned with the clip position. This means bike operation between 1/4 throttle and just below WOT. I would not be at all surprised to find your bike runs better at the 2nd down from the top/flat.

Once that is all good, then you can work on the bog/hesitation. This is controled by the AP. Being your complaint is only of a slight bog, it probably has an appropriately sized leak jet. It is possible, an oring (search for oring mod) on the APlinkage is all you need. If that makes it better but not perfect, then a 1/2 turn of the AP timing screw may be the ticket. Keep in mind, testing must be done by riding. It does not matter that the bike does in the garage.

[skinnybob]

So test rides are only around the neighborhood, and now i have angered my neighbors, but oh well. I need to get it out on the trail, but this is where i ended up, and so far it looks promising.

still 45 pilot, but now 1.75 out

155 main

jd's red needle on 4th groove

decel pop seemed to vanish, the trips around the neighborhood didn't get any hanging idle, and it pulled hard to the top with no bog.

so once i can get it out on the trail and ride it for real, at this point i'd say i'm there or at least really close.

Thanks for all the input.