Idle surges and eventually shuts down

[atzelaner]

Does anybody had this happen before or know what causes it?
My 2012 C5 classic idle RPM hunts (goes up and down) and eventually after 1 or 2 minutes shuts off. I can start it again and the problem is gone for a while, but even after riding a hour or so if I stop at a redlight it sometimes tries to stall out again. Took it to the dealer and they could not find anything, so they just increased the idle RPM and said to come back if the problem persists.

[motorat]

yep mine does the same thing.
when i had the uni filter the idle went up alot and i thought that it running poorly was because of the lack of an air box so i put the stock air box and filter back on. now the idle is alot lower and it will die if i don't give it a little gas.

[Ducati Scotty]

Having the idle too high or too low can cause all manner of running problems.  I would also recommend getting an NGK spark plug to replace the stock Bosch plug.  The NGK plug should stop or minimize the hunting.  Once that's stable you should be able to set the idle properly and I suspect it will run much better.

Scott

[Jack Leis]

+1 Scotty.

[Arizoni]

Changing the spark plug is a good move but, when my 2011G5 was new even that didn't totally remove the tendency of the computer to hunt for the right idle speed and, occasionally the engine would die at a stop light.

I ended up lowering my idle speed using the large brass screw in the top of the throttle body.  This helped reduce the "hunting" but sometimes it still would die.

That's when I learned the old 'trick' of listening closely to the idle speed when at a light and if it sounded at all like it was going to quit a slight 'blip' of the throttle kept it running.

As I understand it, the big singles back in the old days often needed a little 'blip' every so often to remind them who was the boss.

Anyway, after getting the bike thru its break in milage the dieing problem seems to have gone away.

[GlennF]

Big block V8's with a lumpy cam and a blower often require a similar technique at the lights

On a more serious note ... my B5 with a new plug and slightly faster idle improved a lot. It also seems to settle as the engine gets older.

[motorat]

mine has the ngk bp6res plug and 4700 miles.
i think that when i put the uni filter on it reset the computer...since i had the problem with water in the gas i put the stock set up back on. while this setteled the idle now i have the condition that
atzelaner stated. since i have only riden about 100 miles since putting the intake back to stock i think that the bike has not reset itself. it does seam to be running better--still have a little water that i an chasing.

i could be wrong----i usually am.

[barenekd]

I guess they all do it. Mine did it initially. Changing the plug helped a lot. Resetting the big screw helped, too, but it was a very small change, about the width of the slot. Putting a lot of miles on it helped a lot, but it will still hunt on occasion. I do a lot of altitude changes in my riding and that probably adds to the bike's confusion.
Bare

[Ducati Scotty]

It's best to get a tach and set the idle to spec with the engine warm.

Scott

[mattsz]

My B5 arrived with a wicked high idle, and it hunted like crazy, but only while in gear with the clutch in.  In neutral, it maintained a steady too-high idle.  Go figure.  That was after changing to the NGK plug.

I adjusted it down, using the "big screw" at the throttle body; unlike Bare's small adjustment, mine took more than a full 360 degree turn to get it down to a sensible idle speed.  But it still can't decide.  It no longer hunts much, but once it's warmed up, when I come to a stop during a ride it will settle to an idle speed somewhere, anywhere, between 1000rpm and about 1600rpm, seemingly at random and without any knowing of where it will be until it happens.  I figure it must be the "computer", since it doesn't happen when it's cold, which, as I understand it, is when the system isn't adjusting things on the fly.

Another apparent effect of reducing the idle to about where it should be (I think I settled on about 1200) is that I can no longer kick start it when it's cold.  Once it's warmed up, no problem, but first ride of the day, even at about 50 degrees F, I absolutely cannot kick it to life.  And as we know, every kick without starting adds to flooding the engine, which I have done.

I have about 3 riding months and 2000 miles on it, and I still don't have the solution to the problem.  Here's the thread, with some video links and everything:

http://www.enfieldmotorcycles.com/forum/index.php/topic,15424.msg165913.html#msg165913

It wanders around between idle speed and sticking clutch plates and clattering decompressor.  But the idle speed issue doesn't have a satisfactory conclusion at this time...

[GlennF]

Another apparent effect of reducing the idle to about where it should be (I think I settled on about 1200) is that I can no longer kick start it when it's cold.  Once it's warmed up, no problem, but first ride of the day, even at about 50 degrees F, I absolutely cannot kick it to life.  And as we know, every kick without starting adds to flooding the engine, which I have done.

You can clear a flooded engine by turning ignition off and kicking through a couple of times.

With my B5 I kick once with no throttle or enrichment at all. If it does not start with that kick I turn off ignition kick thru a couple of times, find just past TDC and try again with throttle cracked about 1/3 or so.

Also kicking whist on the center stand helps when cold you get a better kick.

[Royalista]

+1

When really cold I use the "manual bi-starter" and 1st kick does the trick.
I pull on the lever, kick & release lever, engine is running.

"Manual bi-starter" isn't precisely a choke but a help for efi when cold. That is how I understand the manual and it does work for me that way too. Hope this helps, thumbs up.

[mattsz]

Well, seems like there is something amiss with mine, then.  Hopefully I'll be seeing a dealer in the spring; they might have some ideas...

[Royalista]

Mattz,
I've been viewing/hearing your video on the other thread.

Have you ever thought that it could be 'just a loose screw' causing the trouble? I'm thinking of the elements of the auto-decompressor. If loose they would still be contained, work, but cause rattle at certain rpm's.
If so it would also explain the no-KS in the cold.
The workplace manual has a blow up chart at page 04-12.
Get some second opinion before committing to open heart surgery. I might be wrong, it's just an idea that keeps popping up. Pirsig says you have to give them some attention. (heheh, that gets me off the hook)

I know the feeling of these gnawing issues. Just keep swimming...

[mattsz]

Royalista-

The guys who I've been led to believe are trustworthy here (you may or may not know who you are...  but I do) have, if not claimed there is nothing wrong, at least assured me that it sounds plausible and that I should definitely ride it as it is and it may likely improve with a few more miles.  My clatter lasts a few of minutes idling in the cold, and I only have to ride it for a minute before the bike is warm enough and the clatter is gone - and it must completely cool down before I hear it again...

As it happens, in the next 6-8 weeks I will be opening that side of the engine to change out the drive sprocket (so I can upgrade my chain), so I'll have a chance to poke around at that point - hopefully I'll have some extra input from here when the time comes...