'05 FE550 jetting issues

I bought a very low hours '05 FE550 last spring and have never been completly happy with the carburation. It has always started very easily, idled fine, accelerated cleanly with no bogs. The original owner had installed a R&D adjustable leak jet kit including ACL pump spring, raised the needle (OBDVT) one notch (6th) and, I believe, put a richer pilot jet (55) in it. My primary complaint is that the bike is way too responsive right off idle - like downright scary on technical trails. I've been riding big-bore bikes for years and this is my 3rd Husaberg. My '96 FE501 was much easier to ride at low speed as was my '02 FE650, although both of them had Delorto carbs and SEM ignitions which may have contributed to their being a bit more docile. I barely crack the throttle on this 550 and it jumps. Neither of my RFS KTMs (400 & 450) nor the YZ400F I had in the past had anywhere near this much throttle response but nor did they have this much hp either. My 550 is almost as much of a handful as was my '87 Husqvarna 500XC.

I've checked various posts on this site regarding jetting and from what I can gather the pilot jet is way too rich (owners manual lists a 38) and the stock main jet (182) is too rich. even with the 55 pilot it idles the smoothest with the fuel screw 2-1/2 to 3 turns out. I've tried pilot jets all the way down to a 42 but the bike dies as soon as I turn off the choke with anything smaller than a 52 and then it has a bit of a bog on acceleration. I removed the R&D adj. leak jet kit and installed the OEM acl pump spring, installed an OBDVR needle (clip in 5th), set the acl pump adj. screw to Sudco's recomended setting, installed a 172 main that I found in my jet collection, and tried it again tonight with a 45 pilot jet. The only way I could get it to idle is with the fuel screw about 3 turns out - approx. the same setting as with the 55 pilot jet. If I open the throttle very fast there is a bad bog but the immediate off-idle responce is still very abrupt. I rode it around for a couple of miles and even thoroughly warmed up there was no improvement.

BTW, I live in SE WA, the elevation is about 1000', and use only premium gas with no alcohol

Any ideas?

The thing that bugs me is that no matter which pilot jet I install it idles best with the fuel screw 2-1/2-3 turns out. Also, the fact that it starts best and idles great with a 55 pilot jet makles me wonder what is different about my particular motor. I had given some thought to disconnecting the acl. pump to see what that would do to the jerkiness right off idle. I have shot carb cleaner and compressed air through all the orfices in the carb thinking that maybe something in the pilot circuit was a bit clogged but that made no difference.

What puzzles me the most is reading the jetting specs. others are using successfully - i.e., 38-40 pilot jet, fuel scew 1-1/2-1-3/4 turns out and mine won't run with those settings.

Sparks, what needle are you using? I am thinking about moving the clip on my OBDVR to the 7th (bottom) position to see if this will clear up the bog/hesitation when opening the throttle rapidly. (That issue improved when I moved the clip from the #5 to #6).

The air leak idea is one that I have thought about a bit and does make sense. I have never looked at the baffle plate / diaphram on the slide. As far as the intake manifold is concerned, are you refering to the rubber part or the metal? Every time I change jets I have to remove the rubber intake boot to get the carb out and it seems to be fine.

I worked on the 550 a bit more this afternoon and found that the screws for the intake bell were both somewhat loose, so it was removed and the o-ring examined (looked good - and the dealer didn't have any in stock) and it was reinstalled with a bit of silicone to make sure and get a good seal. The rubber intake manifold was examined and again looked good. Just for good measure, I removed the slide and replaced the rubber sealing gasket between the slide and baffle plate; but again, it looked fine. After re-assembling the carb (this time with a #40 pilot jet) and putting the bike back together I actually got it to start with the #40 pilot jet but it would only run with the choke on until I turned the fuel screw way out. I then took off for a test run but made it only a couple of blocks before the bike would just die whenever the throttle was closed. Back in the light of my shop I found that the fuel screw had backed out and was laying on the starter - the spring, washer, and o-ring still on it, thankfully.

My assumption was that there was an air leak which is why the bike would only idle well with the #55 pilot jet but after tonight I'm not sure. Something is making it run way lean, but what? Tomorrow I will again check the pilot air passage for a partial blockage but aside from that I am stumped. This is the 5th bike I've owned with the FCR carb and the only I've had problems with.

Well, took the carb back off and apart and found that I had indeed installed the slide plate upside down (note to self - do not work on things like this late at night and when tired). Checked the pilot air jet and passageway and shot carb cleaner/compressed air through. Put everything back together with a #40 pilot jet and again, the bike would not ide smoothly unless the fuel scew was 4+ turns out and the bike was hard to start. Tried a #42 pilot jet and the same except it was 4 turns out to good idle. Put a #45 pilot jet in and the bike idled well @ 3 turns out but still had a bit of a stumble when the throttle was opened quickly. Re-installed the R&D adjustable leak jet and was able to tune the off-idle stumble out even though I have the ACL pump backed all the way off.

I just got back from a 70 mile test ride - a bit of pavement, gravel, very rough dirt road, about 4-5 miles of technical single track. The bike works better now than it ever has. With the ACL pump backed off the jumpiness in tight 1st gear situations is gone and the bike is now very manageable. It also cruises along on the road much more smoothly, although it no longer wants to instantly wheely every time I crack the throttle.
182 main jet
OBDVR needle C5
45 pilot jet
fuel screw 3 turns out

I may try a different needle later on but for now the bike runs acceptably.

One thing I noticed on my '05 FE550 is that the idle/off idle seemed to improve with the needle richened up a notch (OBDVR needle, 6th clip position). I finally received the Yamaha needle recomended earlier in this thread but have yet to install it. If it were me I would definitely check the screws that hold on the intake bell as the ones on mine were a bit loose - after tightening them up the bike now runs fine with a 45 pilot jet where before it took a 55.