What could be causing this “Runaway” motor??

[DaniBoy]

So my Spider has been sitting in my garage for a week with no battery in it. Finally got my new one, topped it off, load tested it, and today I installed it. On initial start, it fired right up and was idling nicely. I “goosed” the throttle a couple of times and the revs started climbing until it got close to 2500 and I got scared and hit the kill switch. I worked the throttle with the motor off and it’s not sticking. I started it again and revved it a bit and it did it again! I killed it again. Once more I played with the throttle, and it snaps right back when I let go. No binding or anything. I replaced the body panels I had off and then tried it again and all was normal. I could rev it, release it, and it responded just fine. I’m hoping that maybe it was just a fluke, or that sitting with no battery caused the computer to forget so it has to relearn? No error codes at all. Thoughts?

 

[IdahoMtnSpyder]

Probably just a fluke. There is nothing mechanical about the throttle other than the butterfly valve in the intake. The throttle is all electronic so turning the grip with the engine is off does nothing. The engine must have gotten some sort of spurious signal from the throttle grip circuit but I doubt that.

OOPS! I just noticed yours is a 2010. I could be wrong about the "throttle by wire" bit. It seems to me I have read the earliest Spyders did use a mechanical connection from throttle grip to engine. The above comment might be worthless!

 

[DaniBoy]

Yes, mine has two cables, one pull and one return that control the butterflies. The way I understand it that having two cables is like a failsafe. One pulls the butterflies open and the other pulls the throttle grip back home. Even after I let go of the throttle the first two times it happened, I could feel it snap back to idle position. Thats’s why I can’t figure it out. We shall see . . . When the weather warms up enough for me to ride.

 

[Woodaddict]

carbon deposits around the butterflies?? might need to do an internal investigation, with being a 2010

would not be concerned with a stick at 2,500 rpm, maybe redline - yes

 

[BajaRon]

There were throttle body issues with some of the 998's. Have you been into your air box? That would tell you a lot. You could visually inspect what your butterflies were doing and whether or not they were closing all the way. A good cleaning may be all that is needed.

There were also issues with oil coming up through the crankcase vent tube which can create issues with the throttle bodies. However, since you have the cable actuated throttle setup. The return cable should not allow the issue you are having. I wonder if you might have a vacuum leak somewhere. I would suspect the PCV valve not closing. That is easy to check by plugging the hose leading to it. I also highly recommend removing the evap canister. Which would remedy any PCV valve issue as well.

Let us know what the final fix is. Always great information for the next guy.

 

[Peter Aawen]

Any of those other things mentioned above could be coming into play here, even a spurious signal from one or more sensors is a possibility I guess, but given what you've told us and that you mention it's really too cold to ride over there atm, I reckon it's more likely that your computer was simply telling the engine to rev a bit more than normal cos the fuel pump hadn't yet quite pressurised the system enough or cos it was a tad cold (was it a tad colder'n your usual summer riding temps?? :dontknow: ) so while the engine had started, without those extra revs it'd either be hunting a bit or maybe running a tad lean; or maybe it was just not running fantastically/all that well on old gas? :dontknow: Regardless, I reckon it'd be the Engine Control Unit/computer was calling for more revs just to keep things running properly, as it does and should whenever necessary on first start up.... :thumbup:

Remember that these Rotax V-Twin engines rev a lot harder than the 1330's do, and also rev harder than many bikes you might be more used to in the States, so possibly unlike everything you're more familiar with, 2500 rpm ISN'T revving all that hard at all for one of them - in fact, it's not too much higher than 'normal' idle for a Spyder V-twin; maybe possibly juuust a tad higher than the 'fast idle' that you might expect to hear from a regularly run Spyder V-Twin starting up on a cold morning; and besides, those revs are not yet high enough revs to even fully lock up the SE5's clutch!! Just for comparison, my Rotax 998 V-Twin powered 2013 RT tends to rev a little higher than 'normal' if I start it up when it's standing in the cold , especially after it's sat for a while, altho I've never bothered to check the revs or checked how long it continues to rev like that, cos it's pretty much normal & acceptable/expected behaviour for them to rev harder in those conditions. But if yours starts revving up hard all the time; or revs towards 5,000 rpm on that first start-up, then those ARE getting to be highish revs for a computer to call for on a first start; and if it starts revving over 8,000 rpm on first start up ever, then it might be heading towards an engine run-away, but not before that! :lecturef_smilie:

So really, Dani, at my 'first glance' of all this, I don't think toese revs & the engine behaviour you are expressing concern about are really all that unlikely given the circumstances, nor should either/both be an issue for that motor in those conditions.... in other words, even if it does something similar on other coldish mornings &/or after you haven't ridden for a while (even just a week or so...), then I don't think you really should worry too much about it; it all sounds pretty normal, even if it's not something you've noticed or been aware of happening before! It's probably because of your week long 'enforced break' in riding followed by doing some wrenching on it that you're being a little more aware of things like this atm. :thumbup:

Sooo, I reckon you can comfortably just Ride More, Worry Less - unless it starts getting worse or happening all the time of course! hyea:

 

[BLUEKNIGHT911]

:agree: with Peter's assessment ..... Unless you are going for a ride ( 15 min or more ) never run a combustion engine in winter ..... JMHO .... Mike :thumbup:

 

[Rd_Runner]

The older 998 V-twins also had a problem with the vacuum lines coming off of the throttle bodies. The OEM lines were rubber and over time the heat will cause them to crack and leak. Usually when you get a vacuum leak around throttle bodies or carburetors the additional air results in a higher idle speed. If the vacuum lines are cracked replace them with silicone lines cut to the same length.

Mike

 

[DaniBoy]

I also highly recommend removing the evap canister. Which would remedy any PCV valve issue as well.

Let us know what the final fix is. Always great information for the next guy.

I’ve seen videos on that, although not explainative enough. Tell me if I’m right: there are three lines going to the canister. The one that is the fuel tank vent gets a fuel filter (check valve) installed and looped so it goes above the tank level and then down to the ground. The other two get plugged with bolts. I’m wondering about those two with bolts. Instead of a boly in each, I’m wondering if the ends of them can just be put together with a coupling?

 

[ARtraveler]

I believe the idle point for the 998 twins is around 1300. That is compared to the 800 or so for the 1330's. 2500 is still to high....but 5500 is the recommended running rpms for the 998's.