Hi!:) As some of you might've followed, I've put my bike together after removing the sas, epc, and cleaning the carbs, plus I've set the needles to the 3rd clip.. Everything else is stock in the airbox (paper filter, jetting), and I have Akras without the dB killers. Mixture screw 2 and 1/4 turns out, float height set to 3mm. (I live below 1000 feet) This is an EU bike, so it doesn't have the canister out of the factory, and the float bowls are also vented properly. Now the bike runs like a champ, no surging, only a slight backfiring when throttle is shut at let's say 6-7k rpm, but nothing as compared to when the SAS was still in place. It starts good, and runs good, Choke will kill the engine when hot, so I think everything is pretty normal, except for one thing: The idle is hunting.. When cold, it is hunting +-100-200 rpm, and when the engine get's hot it's worse.. I set the IDLE for about 1400 rpm at a red light, then ride 5 mins, and at the next red light the idle is hanging @ 2000 rpm. Then if I blip the throttle a bit, it will usualy return to 1400, if not, then I set the idle back to 1400, and it goes on like this for about every red light:) Then at one point bliping the throttle is enough for it to return.. Okay, this was a quite complex sentence, hope it's clear what I've ment Throttle cables have slack, and I've checked the carb boots, and I think they are fine, so are the vac ports on the intake manifold. Two thing what I didn't yet do: 1. carb sync 2. TPS calibration - Keeping in mind, that the bike runs OK, pulls hard in all of the rpm range (wheelies like never before), what can be the cause of the idle hunting + the idle hanging? thanks!:) edit: fuel pump has about 1000miles in it, and the valve clearance was set about 1000 miles ago also. (Everything was fine before the SAS/EPC removal + Carb cleaning, but the air screw was @ 1.5 turns, and the needle clips were 2nd from top.) At least it doesn't cut out when comming to a stop and pulling in the clutch, like it sometimes used to do before..
Hunting +/- 100 rpm at idle isn't a big deal I think - well mine does it anyway. But hanging at 2000 rpm suggests something wrong. Probably an air leak somewhere - try reseating the carbs, maybe with a tiny smear of rubber friendly grease where they insert into the rubber boots. It's a paint in the bum to trace problems like this, often you take it apart, put it back together and the problem is fixed without you knowing what exactly you changed :)
These carbs are really hard to get perfect. Our setups are similar, and our elevations are similar. I have my floats at 2.5mm, my needles at the middle setting, and my IMS out 2 turns currently. I have no hunting, but I do have to adjust the screws based on temp - two turns out in summer and around 2.5 turns in winter. I had your symptoms for a long time. I think your setup is probably just a little rich, and that causes these bikes to hunt up on RPM at idle when hot. But, if you lean up the bike too far with the screws, the symptoms are similar. They are just really hard to get right. I solved all of my problems by installing Flex Jet 2s on the bike so that I can adjust the mix at any time. Are you syncing the carbs? You need to do that as well. I use the air flow meter mentioned in the HOW, and it has worked well. As to the TPS, if the bike is starting properly it's probably correct. But, it's easy to check.
These things are a bitch to get dialed in right. I'm at 1000' too and even had mine set where your bikes is set once. I found that while it fixed the mid throttle it left the bottom rich and the top lean. Eventually, I evolved to bigger mains to fix the lean top end issue, 172's iirc and lowered the needle back to 2, floats at 3mm. Even then its still a bit of a compromise, still slightly rich at idle and slightly lean at wot. These carbs are ultra sensitive, one slight change is sometimes all it needs.
Thanks for the suggestions and posts! I'll try to adjust the mixture screw a bit tighter (maybe 1.75?) and during this process I'll also reseat the carbs! Thank you guys once again!
Is it normal (no matter if 2nd or 3rd clip on the needles) that EVEN when idling and throttle is closed, the needle leaks fuel by (leaking between the needle jet & needle)? This is what I've seen today on my bike.. (at least the idle is not hunting that bad, when the clip is in the 2nd position & IMS is @ 2.25)
This is just a guess, because it's what I saw on my bike... What is the condition of your Choke Cable? Mine had a cracked casing, so the choke would not close all the way when cold, and then when things warmed up, or there was vibration, the cable would slowly slide down and allow the choke to close all the way. Just a thought. But still, it sounds like your bike is running much better than mine so you should be happy. Q~
Haha:)) You're right:) I should be happy! However the choke cable looks fine, I triple checked it today just to be sure..
Is there a part# for the jet needle (the part where the needle slides in-out)? Is it changeable? Does somebody know? Or do I have to buy new carbs because of the jet needle leak?:S
Anybody? with the clips back in the 2nd position, and IMS @ 2.25, it's still producing the SDS (sudden death) - one of the cylinders cuts out /farts / at idle... I'm sure that there is no intake leak, also the valves were set 2k miles ago.. I'm out of ideas.. So if anybody could help, or anybody know if the needle jet - needle leak is normal (dealer says it is), then please let me know! Also yesterday I was idling the bike at home for about 20 mins, to finally discover which cylinder is farting.. But ofcourse it haven't missed a beat... Thanks!
If by "needle jet leak" you mean fuel coming out of the needle jet hole during idle, then yes that is normal. It would be impossible to say if you are getting too much fuel "leaking" without actually seeing the bike at idle. Changing the needle clip position will increase / decrease the amount of fuel "leaking". Because of this, the clip position will affect the idle mixture. Dave
Thank you sir! Yes that's what I've meant! Well if it's normal, then I'm out of ideas what could be causing the sudden death syndrome / carb fart @ idle + slight idle hunting.. But it's quite annoying to ride through the city with the bike shutting down at almost every red light.. Maybe I should buy the flex jets, and see if I can eliminate the problem with those.. but I'm quite skeptical.. Could it be the ignition? coils?
I know this sounds too simple, my '06 idle didn't hunt, but would drop a hundred or so rpms, I'd adjust the remote idle control. An hour later, it was 100 or so rpms high. Seat of the pants experience - poor fuel. Not old fuel, just pump gas here in Ohio. I'd have trouble throughout the day, fuel up before parking it - the next day (next tank) - everyting o-tay. I know it sounds too simple, but, you never know. Occam's Razor, perhaps. .. . - good luck.
I'll try to run some 100 octane fuel next time I fill up (instead of 95), just too see if it changes anything.. Thanks for the suggestion:)
Have you done the carb sync yet. Mine was farting out of the rear cylinder exhaust and bad on decel. Fixed with a sync (done at about 4000rpm). Farting/backfiring gone. Easy to do if you have the instruments and I have the two capped tubes that run along the right side of the frame from the inlet manifold. To check for leaks grab some aerostart (ether) and spray around the carbs and rubber boots and listen for changes in idle.
Ok, so I've tried running it with 100 octane premium fuel.. There is no difference at all. Still hunts and farts. - Is there a way to check if the ignition coils are shot? Can they act like this? - I've read that the carb bodies have some unaccessible tubes in them. Would cleaning them with an ultrasonic cleaner help? Thanks for any suggestion!
One thing I've figured out yesterday is: Holding the two vac. hoses that comes from the cylinders (blocking the holes with my finger): If I let go the rear cylinder vac. hose (creating a vac. leak): The engine RPMs increase from the 1400 idling speed to about 2000. If I let go the front cylinders vac hose: The engine RPMs drops from the 1400 idling speed to about 1000 rpm. If I connect the two cylinders with the vac. hose it backfires like hell Is this any cue for someone?
Rear cylinder running too rich? When you allow extra air in, the mixture is better so the engine speed increases ...? I'm not certain of that, but you could try turning the rear idle screw in a bit. The rear main jet is bigger, and the main jets do affect idle mixture to some extent.
I had the same issue along with surging with bike in natural at 3000rpm. See this: http://www.advrider.com/forums/showthread.php?t=285455 Messed with the floats and did a valve check (that meant changing 7 shims )over the last winter. Result was idle hinting just like yours + surging. Finally hunting when away and surging got better(can't notice it when riding) by changing low speed air jets from 45 to 42. That's it. It was way too rich for some reason with #45. But the mystery remains that all was good last year with 45 jets. Im guessing valve check was too aggressive. I hope it helps.