Engine Dies When Clutch Disengaged & Throttle Blipped

Hey, all,

I have searched the forum, but have not been able to find anything on this particular problem (there were a couple of threads on the engine dying when the clutch lever is pulled in, but, in my case, it only dies if the throttle is blipped while the clutch lever is pulled in [as during, especially, for example, downshifting]).

Sorry, the bike is a 2002. Regularly maintained, never dropped. About 18K miles. Engine runs great when in gear, and it will run fine when the clutch lever is pulled in (clutch is disengaged). But, blip the throttle while the clutch lever is pulled in (again, as during downshifting), and the engine will die. This happens consistently in any gear. So, the only way to downshift (or upshift) without killing the engine is to not blip the throttle during gear changes (during the disengaging and reengaging of the clutch).

Incidentally, the engine runs fine when in neutral.

I would appreciate any thoughts on this issue.

 

have you tried boosting up the idle speed ??

 

Although I haven't boosted it up, the idle speed seems to be fine - the engine doesn't die at idle, i.e., it doesn't die when, with the bike in gear (any gear), only the clutch lever is pulled in. It's when, with the bike in gear, with the clutch lever pulled in, the throttle is blipped that the engine dies.

It doesn't really make logical sense, I know, but that's what it's doing.

 

Well if it only happens when the clutch is pulled in and the bike is in gear, I would look at the sidestand kill switch circuit. Perhaps the engine is torquing in the frame when the throttle is blipped and that is shutting down the engine. Very long stretch but what the heck you gonna do.

 

Yeah, I actually thought about that, that somehow some strange combination of harmonics/vibrations is causing the sidestand switch to kill the engine...

Would appreciate your advice on what would be the best way to temporarily disable the sidestand switch, to see whether this hypothesis checks out.

Also, a buddy threw out the possibility of a clutch lock-out switch being involved, although he wasn't sure how it could be involved. I don't even know what that is. Would appreciate some elaboration if this indeed can be the cause.

 

to eliminate sidestand switch, just put a jumper wire across the connector terminals going to switch, same with clutch switch i guess.....

 

BTW, the battery seems to be fine. The bike will start back up immediately each time, and, when the engine does die, the lights stay on.

 

For what it's worth, I had this last fall. Not consistently, but around once a week (usually when pulling up to toll booths, that kind of thing). After about three months of this, it died for good in traffic and wouldn't restart. The stator had been marginal and finally died on me. Replaced the stator about a month ago (as well as the reg/rec) and it's been fine up until today when it happened again. I was able to immediately restart the engine, but it's got me nervous. I'm going to clean heck out of the sidestand switch and see what happens... I am guilty of spraying grease and WD-40 in that area as part of my weekly maintenance, so maybe some dirt got in there.

 

My bike does that too, pretty much the exact same thing. It seemed to not happen at all over the winter, but now that its warming up, its happening again. Doesn't do it all the time tho.

I also noticed that when I blip the throttle and it doesn't die, the motor seems to have stopped for a slip second but fires back up ( the tach drops to about 500 rpm before popping back up to 1500).

My bike is a 99 by the way.

 

I had an 04 that would die when coming to a stop with the clutch pulled especially if I blip the throttle. I call my buddy at the dealer where I bought it and he asked if I let the
FI light go out before I started it. I told him "of course I did What do you think I am stupid?" And it never happened again.

 

mine runs great after I blip the throttle.....

check you stand switch.... that may be the culprit...

 

After reading Bweiss' comment, I should also mention that mine's a '99 as well (though I doubt it's related) but more importantly, it only happens once the bike's warmed up. I've never had the engine die when it's cold. Also, when it's cold, the idle doesn't wander more than -/+ 25RPM. When it's warm, the idle is rougher and wanders -/+ 150RPM. In addition, when warm, it lugs under 5000 RPM, and will actually stall if I take off from a stop below 3000 RPM. Cold, it runs fine.
I've been told the throttle bodies might need to be synced, and the spark plug wires' resistance may need to be checked. Will check those... been procrastinating for some time.

 

I just bought a 2005 and have had the same thing happen to me three times. Each time it happened when I was blipping the throttle for a downshift and then had to pull in the clutch to stop. Today when it happened, the engine was warmed up after about 30 minutes of riding. I blipped on a downshift to second then had to stop quickly thereafter for a car in front of me. The engine died and all of my dash lights came on. I hit the starter button to no avail. I had to turn the ignition switch to off, then back on for it to start back up. I have aftermarket Scorpion exhausts w/no power commander and thought that they might be playing a role. Do you all have stock exhaust?