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Stall when giving throttle *immediately* after cold start?

33696 Views 49 Replies 16 Participants Last post by  TMF
So I start up my bike the other day, ready to roll to work, and and just as I was letting the bike in gear the engine just died. I started it back up, same thing again. Started back up again, and let the engine idle for a little bit, and then all was good. I repeated the test tonight - I immediately gave the bike throttle after a cold start and the engine just died. Then I started back up and let the bike idle for a little bit, and then I gave it some throttle and the engine revved up just like normal.

Any idea what would cause this? I don't know if our bikes are cable throttled or electronic, but if it's the latter I would have assumed that the ECU would account for cold start parameters. The only thing I can think of is (assuming cable throttle) that I'm dumping tons of fuel in and that kills the spark. But if that were the case, I probably should have run into this issue many times before.

Anyone ever experience this? While riding I also felt some really choppiness at low speeds/rpms. At first I thought that was the road and the suspension, but now I'm wondering if it's related to this somehow.
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The problem is that the fuel is too rich after applying throttle, rather than too lean. You are effectively flooding the engine. You see, when the bike starts up, a richer fuel mixture is provided until the engine warms up. The mixture is even richer when the temperature is lower, because more fuel is needed due to the denser air. When you give it throttle and more fuel is injected, it ends up being compounded because the bike is already pushing a richer mixture. The fuel isn't burning quick enough, and the fuel-to-air ratio gets to a point where the fuel will no longer ignite. It is starved for air and won't burn, and as a result, the engine dies. Actually I just made this all up and am completely talking out of my butt. But I did stay at a Holiday Inn last night.
well for pulling it out your ahole I think you might have nailed it. sounds very logical to me.
A sticky fuel injector, only when cold? 33 seconds later, it warms up and works fine? Being we have four injectors, every one needs to be acting the same way. This bike will run on one, two or three cylinders.

Heres how we can check for this. Strip bike down, and find a temporary fuel source. Hook this up.
Remove one injector, and put it in your mouth. Start bike.

Now, with injector in your mouth, notice if the flow changes after the bike warms up. If it does, theres your answer. If it doesn't try the next injector until you've done this four times.

Will it help? No. It will teach you that warming up a piece of equipment is a good idea, and much better than going through this.

Or, go back to Vics post and figure out the real answer.

Our fuel injection, and its exactness is what makes us think this is even an issue. Its not. Back in our carb days, it was very normal to have to restart the bike a few times, when cold, due to a bad guess on the choke position.
hahaha good idea. maybe easy should put the injector in his mouth, start bike and see if it injects any smarts in his pee brain !
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The simple truth is modern engines run so well and are so reliable that we often forget what it was like not all that long ago.

My guess is the weather was a little cooler that day, and the operator was not 100% used to the bike and it's habits.

It was on cold start, which is overly rich, and not on the most amazing ignition map. The oil was not warm yet, so any attempt to put the bike in gear would most likely make it die as the clutch plates are all stuck together.

Then trying to restart, on a rich mixture, with left over fuel in the intake of cylinders....

This is just slightly annoying, but nothing too serious I would bet.

Remember the first bike you ever got? There was a learning curve about EVERYTHING. It was super exciting and super worrying at the same time. Heck i think that is the reason some people buy new motorcycles, so they can feel a little bit of that again.

He is not completely used to the bike and how it acts.

No reason to loose friends, or respect for people over this. Don't let anything as small as life get you down.
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Too rich the engine will sputter for a second or two when opening the throttle.
Too lean will just cut out for a short time when opening the throttle.
I vote too lean due to the exhaust emissions tuning from the factory.
My 2, you're getting too complicated here, I mentioned bad gas because - *sputtering accompanied the other symptoms right? I can tell you that if 60 degree weather was at play here in a Texas environment then 60 degree weather is relative to my FL enviro and I say, I tell you, that I have started and trusteed at a lot lower than 60 degrees here at 5AM when I leave to get the hell out because of respect for the neighbors that you can put this bike in gear and GO! C'mon OP how bout a resolve.

EDIT did you run the tank thru? It worked itself out? You are not challenging it to move forward with out proper warm up? It's on you now. :) :) :) :).

* actually I misread the OP, not sputtering, "choppiness at low rpm" so that's unclear in that it may be as suggested operator familiarity with this bike.

Either way I hope you got it worked out and are enjoying it now.
Too rich the engine will sputter for a second or two when opening the throttle.
Too lean will just cut out for a short time when opening the throttle.
I vote too lean due to the exhaust emissions tuning from the factory.
We are really not lean from the factory. If anything it rich. A stock power commander map for a stock bike takes more fuel away than it adds
finally got a chance to ride the bike enough and i think part of it was bad gas. it definitely idles much better.
finally got a chance to ride the bike enough and i think part of it was bad gas. it definitely idles much better.
Good to hear it's running better. Sucks not being sure your bike's ok or not.
Its not gas, seen this happen to a fuel injected motorscooter with only a few thousand miles on it. The bike DIES ALOT unless you let it "warm up" .. really it has to get HOT. Even still, it will die twice in the first 3 miles, then it can go 10miles or more without dying at all. Diagnostic Tool says system is fine, no trouble codes at all. I checked engine valves and many other things, bike seems fine in all respects expect DIES several times in the first few miles unless engine is red hot. I still dont know whats going on and cant sell the bike so I just ride it myself for errands.
Add fuel injection cleaner for a tank or two.
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