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Rv6John
11-10-2011, 09:22 PM
Hello everyone, I just got a 2008 550 last Saturday and put 80 miles on it in the twisties Sunday. I was all smiles, more then I could of hoped for in a bike.

I rode it again Tuesday and after 30 miles was following traffic and the bike was not happy, throttle got twitchy and the engine seemed to buck slightly. Thought it was loading up and when I cracked open the throttle it wound up normally.

Going to the gas station it stalled when I pulled in the clutch and then three times on the way home when I had to stop. It always started right up but I had to hold the throttle off idle for it to run. Otherwise it accelerated and ran fine.

I thought I would be looking for a vacuum hose off, etc.

Today I finally had a chance to look at it and it started and idled just fine!

The only thing I saw after searching the forum is that my idle speed was slightly low at 1800-1900 rpm. I bumped it up to 2100 rpm.

Does anyone have any ideas as to why it suddenly would not idle then go back to normal ops?

Thanks.

I'm beginning my love/hate relationship with italian motorcycles.

SIR REAL ED
11-11-2011, 08:34 AM
Perhaps at the lower rpm of 1800-1900 your decompresors were kicking in enough to kill the motor. Most of the posts I have seen recommend a minimum of 2100-2200 rpm idle.

Also check to see if one of your plug wires is touching or very close to an exhaust pipe. An incredibly obvious problem I failed to notice.....

Rv6John
11-11-2011, 09:13 AM
Thanks, I'll check the plug wires and ride it again.

I see I need to do a search to figure out what a decompressor is!

z1 zonly
11-27-2011, 11:52 AM
Please let me know if you found anything. I'm a new SXV550 owner with the exact same issue.

rocketnz
11-27-2011, 04:42 PM
defo have idle set to around 2200.

I have it on 2400 when cold (or it will stall), run for first 10 minutes, then drop it down to around 2100, if its a hot day and bike is warm i drop it to around 1800-1900 but only if shes warm or in traffic, idle knob is on back side of airbox by thigh, left hand side

SXVINWA
11-27-2011, 04:55 PM
All are on the left side; right side on '08 and up is fast idle knob... quarter turn unit that replaced the yellow button on throttle housing.

Bike should idle fine when warm as long as it's above the decomp dropping in. I run mine at 2000.

fredgreen
11-27-2011, 05:10 PM
The idle has a mind of it's own. I had my bike for near 5yrs and reset the idle every time I ride it. I ride for 3hrs, stop for 30mins, reset the idle again when I restart.

z1 zonly
11-27-2011, 05:31 PM
To add to the OP, I set my idle quite high, and if I CAREFULLY feather the throttle down it will idle, obviously higher than it needs to be. But anything more than the smoothest of feathering will cause the bike to die. It also bucks and misfires at lower throttle, but is fine at WOT. It feels like some kind of electrical issue--not enough voltage at lower RPM and enough to run great at higher RPMs.

I spent a bunch of time working on mine today, to some avail. Found some things that needed to be addressed that I thought would be the problem.

-Kink in the fuel line from not pulling it down with the tank
-Fubar'd plug wire at the plug tip. I installed a new socket and the problem was still prevalent. Great connections elsewhere (at the coils, etc.)
-Voltages look okay with headlight on and off, at idle and off of idle (but I don't know the actual specs). But the PO installed an HID headlight ballast and bulb and I'm wondering if that's drawing more than the charging system can handle at idle?

I finally removed the plugs, checked to make sure they were the right ones, and cleaned them with brake clean and compressed air (they were sooty and rich). Ran the bike for 20 minutes and the problem didn't happen at all. It's possible that my idle was previously too low, and that fouled the plugs, and simply cleaning them has fixed the problem. I surely hope! I need to do a longer ride to make sure. If not, I'll start troubleshooting again by removing the HID, then by purchasing KWest's cable/software and looking at the TPS settings.

rocketnz
11-27-2011, 06:34 PM
what fuel do you run?

z1 zonly
11-27-2011, 07:22 PM
Filled it up with 93 last night.

fastfoodfred
11-27-2011, 07:32 PM
My 450 is in the shop right now for similar symptoms. I've had it on a dyno twice with the results that its too rich at low throttle openings. With no ability to tweak it, I brought it to my local dealer who now has had their mechanic through several Aprilia schools. So far, the throttle position sensor is all over the place when trying to calibrate it and the high idle knob was out of whack. The exhaust has melted the first battery and I'm guessing this all revolves around a faulty ground or bad TPS. The oil light also comes on from time to time, but it has oil pressure. My guess is a grounding issue at the ECM, since a few things are acting wierd, not just one. I will try to remember to post up when its resolved in the next week or two.

hardtail
11-28-2011, 02:46 AM
Bike would not idle now OK?

--------------------------------------------------------------------------------

Hello everyone, I just got a 2008 550 last Saturday and put 80 miles on it in the twisties Sunday. I was all smiles, more then I could of hoped for in a bike.

I rode it again Tuesday and after 30 miles was following traffic and the bike was not happy, throttle got twitchy and the engine seemed to buck slightly. Thought it was loading up and when I cracked open the throttle it wound up normally.

Going to the gas station it stalled when I pulled in the clutch and then three times on the way home when I had to stop. It always started right up but I had to hold the throttle off idle for it to run. Otherwise it accelerated and ran fine.

I thought I would be looking for a vacuum hose off, etc.

Today I finally had a chance to look at it and it started and idled just fine!

The only thing I saw after searching the forum is that my idle speed was slightly low at 1800-1900 rpm. I bumped it up to 2100 rpm.

Does anyone have any ideas as to why it suddenly would not idle then go back to normal ops?

Thanks.

I'm beginning my love/hate relationship with italian motorcycles.

Check your throttle cables.

z1 zonly
11-29-2011, 09:22 PM
Still haven't been able to ride it and see if the 'fix' was permanent.

Found that the speedometer cable was rubbed badly. Looked in the fuse box and found one blown 7.5A fuse, but I think it was a spare (previous owner must've just changed the blown fuse from previous speedo cable rubbing).

Are the three fuses that are perpendicular to the longer line of fuses spares?

SXVINWA
11-29-2011, 11:31 PM
Yes, those are spares.

Rv6John
11-30-2011, 08:48 PM
Hello everyone, I just got a 2008 550 last Saturday and put 80 miles on it in the twisties Sunday. I was all smiles, more then I could of hoped for in a bike.

I rode it again Tuesday and after 30 miles was following traffic and the bike was not happy, throttle got twitchy and the engine seemed to buck slightly. Thought it was loading up and when I cracked open the throttle it wound up normally.

Going to the gas station it stalled when I pulled in the clutch and then three times on the way home when I had to stop. It always started right up but I had to hold the throttle off idle for it to run. Otherwise it accelerated and ran fine.

I thought I would be looking for a vacuum hose off, etc.

Today I finally had a chance to look at it and it started and idled just fine!

The only thing I saw after searching the forum is that my idle speed was slightly low at 1800-1900 rpm. I bumped it up to 2100 rpm.

Does anyone have any ideas as to why it suddenly would not idle then go back to normal ops?

Thanks.

I'm beginning my love/hate relationship with italian motorcycles.

Follow up: I have ridden bike a couple of hundred more miles and the issue has not re-occured. As I mentioned, I bumped the idle up to 2100 rpm and during the first ride it started idling about 2500 rpm. I backed off the idle knob just a bit and now seem to have a relatively steady 2100-2200 rpm idle.

The bike is a hoot!

Rv6John
12-31-2011, 10:33 PM
Follow up: I have ridden bike a couple of hundred more miles and the issue has not re-occured. As I mentioned, I bumped the idle up to 2100 rpm and during the first ride it started idling about 2500 rpm. I backed off the idle knob just a bit and now seem to have a relatively steady 2100-2200 rpm idle.

The bike is a hoot!

Time for an update. Everything has been fine this last month till today. Ran flawlessly for 75 miles then slowed to make a left turn pulled in the clutch and engine stalled. It started right away but would not idle unless the throttle was held open. Shut off the ignition and restarted to see if rebooting the ecu made any differance. No change. I reached down and turned the idle screw in 1/16 turn and it fired up and idled fine. No issues for the next 20 miles to home. I wonder if there is something quirky with the idle stop screw that occaisionally misaligns? I'm going to take a closer look at that area next time I have the air filter out.

fastfoodfred
01-02-2012, 12:29 PM
My four-fitty came back from the shop Saturday. They said the TPS was bad, the numbers were fluctuating with no adjustments made. They replaced a set of plugs that also only had about 6 minutes of actual run time on them. It's been too cold to ride it, since it is under 60 degrees f, but maybe I will squeeze in a quick ride today to see it it rides differently than before. I'm confident it will, because it now idles and throttle blips crisply, and settle into a nice idle again. It also doesn't lose RPM when the throttle is very slightly cracked open, like it did before taking it in.

Rv6John
01-05-2012, 10:49 PM
My four-fitty came back from the shop Saturday. They said the TPS was bad, the numbers were fluctuating with no adjustments made. They replaced a set of plugs that also only had about 6 minutes of actual run time on them. It's been too cold to ride it, since it is under 60 degrees f, but maybe I will squeeze in a quick ride today to see it it rides differently than before. I'm confident it will, because it now idles and throttle blips crisply, and settle into a nice idle again. It also doesn't lose RPM when the throttle is very slightly cracked open, like it did before taking it in.

Thanks for the input. Right now the bike is running great with no issues. If it starts doing the no idle/stall again the TPS might be the place to look as it may be developing a "dead"/worn spot in the idle position. That might explain why moving the idle knob very slightly fixes the problem. It moves the TPS to another spot. The bike only has 2200 miles on it so it is questionable that the TPS could be worn out already but I guess stranger things could happen.

mtrxv550
01-07-2012, 01:12 PM
The idle speed will increase as the motor warms up. I only change my idle speed at warm up if I am not there to manage the throttle. If your idle speed is above 2200 it keeps on pulling after you let off the throttle and throttle response is compromised. I set mine at 2000 when it's warm and that's where my RXV runs best.

Rv6John
01-29-2012, 11:13 AM
Well it did it again yesterday. Started fine (with a little heater warm up) then 1/2 mile away when slowing for a stop sign it died. Started right up and made it to the next stop light where it would not idle and stalled. Pulled over and turned the idle speed knob in a 1/8 turn. It started and idled with no more issues. On the previous ride I did reduce the idle about an 1/8 turn as it was about 2300.
I'm pretty sure I have a TPS with a bad spot that is causing this intermittent problem. Too lazy to change it now and will probably wait till the next valve check.
I would appreciate if anyone else has this problem and this cures it (at least for awhile)