I have an '08 Sportster and I was wondering if it is normal for them to cough back through the intake when re-starting the engine when the engine is hot. If I'm out for a good ride, say 30 minutes or more and stop for gas, when I re-start the bike it will either cough back through the intake and die or it will start (with or without the cough) and idle high (about 1700 rpm) for about thirty seconds. It will then return to a normal idle and run fine. The check engine light is not on.
It starts beautifully cold and if it weren't for the fact that I'm taking longer rides that require refueling to get home I probably never would have noticed this.

 

when the bike is hot, just tap the starter quickly just enough to move the pistons a bit, then hit the starter and it will be fine....the 1200's have always had a "heat soak" problem, and it does happen on some bt's also

 

I've got a 2007 883, but it has never done that. I have a full stage 1. Is it just the 1200s that do this? Hot or cold it never pop's. Maybe you should bring it to the stealer and get a remap? Check the plug's, see what they look like. If they look OK, then something else is wrong. Check the gap on the plugs, (both of mine were wrong from the factory!). I sent a nasty letter to the dealer and HD for that! I got a free oil change for that. I'd like to know myself why it doe's that I'm gonna turn the block into a 1200 this year. I would like to avoid that problem. Let us know, get it fixed and keep it in the wind................HOLLYWOOD


P.S. Have them check all the sending units on the block, just a guess, that could be what it is................

 

I just started having the same problem when it was COLD after the 1k dealer
servicing; it never happened until after the 1K. I took it back twice without
result and have now left it there demanding that they find out what the problem
is and restore it to its pre-servicing state (which was plenty fine..).

Supposedly they downloaded and installed a modified EFI map, and the problem
has gone away, but I'm concerned that they haven't fixed the problem but
masked it with some ultra-conservative settings that will kill the bike's
performance.

I'm going to check it out tomorrow morning and if they can't tell me EXACTLY
what this remap does, how it differs from stock and why they installed it, I'm
going to leave it there and get MoCo directly involved (I've already opened
a service tracking number with them).

 

No one has ever been able to tell me what the factory remap does,good luck.

 

There are two main causes for a cough back through the intake.

1) a spark or a hotspot lit the fuel in compression stroke before the engin was going fast enough to carry it through top dead center, and the engine spun backwards enough to re-open the intake valve (and exhaust went that way)
2) Your intake valve is leaking enough to ignite fuel that is in the intake manifold

Since your problem started after a remap, I'd guess #1 is the problem. The timing is a little more advanced and the spark is happening so early that the flywheel can't carry through top dead center. Kick back would only get worse if you just bump an electric starter. It would be great if there was a way to run the starter before turing on the ignition, but the enginners didn't give you that option. Back in the days of kick starters, people would kick it once slowly with the ignition off, just to clear out whatever is in the cylinders and get the piston up into the compression stroke before actually trying to start it. A kick back in those days could hurt you, because the kicker would come back up at you.

#2 is much less common, but it is easy enough to check with a compression test. The soulution requires pulling the heads and re-seating the valves.

I'm guessing the initial fast idle isn't really a problem. The ECM is probably just clearing out a slightly flooded condition, usually because the injectors prime the cylinder even though the bike was warm and didn't need it.

Just out of curiosity, do you use the kill switch, or the ignition switch to shut off the bike? I don't think it makes a difference (I believe the ECM treats both the same way), but I'm not sure. I never get an intake cough on my bike unless I stall it, and that is rare. I almost always use the ignition switch to shut it off though. I only use the kill switch as a courtesy to shut off and drift to parking when approaching people.

 

Mine has done the cough but rarley, I think it's less likley to happen if you hold the starter button down a little longer rather than just giving the switch a quick push & release. I read once that the flywheel on a 1200 is lighter than it really should be in relation to the displacement/compression, makes the motor willing to rev quick at the expence of being a bit more clunky at low RPM.
It does often do the fast idle thing when started hot, usually when starting in front of a crowd of people, I hate that, it will rev at about 1500 for a minute or two before settling back down.
I always use the ignition switch to shut mine off.

 

Well, I just talked to two different dealers. One of whom went into extreme detail. Being an engineer I can honestly say he knew what he was talking about. All in all, a high idle for about 30 to 45 seconds is common on 1200 fuel injected Sportsters after a hot start. That's not to say that it isn't annoying, just common. Anyway, they offered to check the intake for leaks as well as check all of the monitored system but they don't expect to find anything since the bike runs like a beast. I'll keep you posted.

 

My nightster does the same thing when it's hot... it coughs a bit if I just hit the starter switch quickly and let it go like you can when it's cold.... if you hold it about a half second longer.. it won't cough back... at least that works for me..

 

I fought this same issue on my 1200 and didn't solve it until the kick-back finally took out the starter pinion gear twice.

I can't speak to the different EFI tuners on the market as my bike is carb'ed, but I solved my problem by switching to a programmable ignition module (Daytona Twin Tec) that has a selectable ignition delay. The unit can be set to not fire the plugs until the motor has completed 1, 2, or 3 revolutions. This solves the problem by allowing the starter to build crankshaft momentum before firing the first plug.

I would think there would be something similar on some of the EFI tuners.