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Discussion Starter · #1 ·
I've now had a odd and disturbing noise during startup two times. Both times the bike had not been started for a couple of weeks. Both times the bike was on the center stand and in neutral. Depress starter, bike starts to turn over, then I hear what sound to me like a metallic 'thwack' and the engine turn over just knocks off and dies. Sounds to my untrained ear like something came lose of hit something. If I were sitting on the bike, sounds like it comes from the right hand side of the bike in the engine area. Anyhow, afterwards, have to feather the throttle to get bike to turnover and start. Subsequent startups seem normal. Anyone expereince something like this before? My dealer says it's not a 'dangerous' sounding noise, but I am concerned. Bike is under warranty tho.
 

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I to have an '03GT.... Can't begin to tell what it could be, I'll leave that to others more mechanically inclined. But for the dealer to say it doesn't sound like a "dangerous" sound is distressing. Probably not another dealer around the area, right?
If it does it again though, I know I'd be right in there to the dealer asking "What the hell?".
Good luck, hope it works out well for you.
 

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I'm not about to even guess what it may be - I'm trying to "picture" something like that happening on startup and I've never heard it.

Is there a way you could record the startup? Might help a bit - since there doesn't seem to be too many responses so far...

alow
 

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I've heard that sound from my bike but it has only been on a VERY cold mornings with possibly a week battery when I've had difficulty starting the bike. It doesn't sound like a graceful stop of the motor and I try to avoid it, but I never thought of it as catastrophic.
 

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If I understand you correctly, the motor spins over and then suddenly comes to a stop?

If it has been sitting for long periods of time, possibly the fuel injectors are leaking into the cylinders, and the starter can't spin over the solid fuel. I've had diesel engines do this. Maybe check to see if your oil level has mysteriously increased. Just a thought.
 

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Chris_in_NY said:
.....and the engine turn over just knocks off and dies.
Can you be a bit more descriptive than this? It's hard to understand what you mean here.

One thought, though, is that you may be having problems with the starter sprag clutch.

Bob.
 

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Chris_in_NY said:
I've now had a odd and disturbing noise during startup two times. Both times the bike had not been started for a couple of weeks. Both times the bike was on the center stand and in neutral. Depress starter, bike starts to turn over, then I hear what sound to me like a metallic 'thwack' and the engine turn over just knocks off and dies. Sounds to my untrained ear like something came lose of hit something. If I were sitting on the bike, sounds like it comes from the right hand side of the bike in the engine area. Anyhow, afterwards, have to feather the throttle to get bike to turnover and start. Subsequent startups seem normal. Anyone expereince something like this before? My dealer says it's not a 'dangerous' sounding noise, but I am concerned. Bike is under warranty tho.

Make sure that the gear indicator says "0" and the neutral light is on. I could not get the bike started once because it was not in neutral, even though it said "0". HTH.
 

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Discussion Starter · #8 ·
more descriptive info

thanbks for the repsonses on this. the bike has definately been in neutral each time this has occured, on the centerstand, and actaully the charger has still been in the bike. i don't suspect a weak battery .. but who knows.

trying to describe this again in the hopes of elaborating more. weird description, but if i had to, imagine a ball on the end of a string, and your spinning it around, then unexpectedly your buddy put a piece of plywood in the ball's path. next time it came around, you'd hear it whack into the plywood and no more 'whoosh' from it spinning ... all quiet. This is what I hear, but it's metallic in nature.

i am thinking of recording my next start-up's, but this darn thing is sporadic!! I do have an appt. with the dealer. they are going to pick up the bike next week, and hopefully they'll find out what's going on here.
 

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Discussion Starter · #9 ·
what about this idea??

I had this thought from my brother .. any thoughts on this?

"I think the starting system on these bmw's is same as a car. Sometimes on a car, the starter motor does not engage or disengage properly. I think the starter spins the flywheel. If the starter popped off the flywheel teeth at the wrong time it might make a big noise. Also sometime on a car (I had it happen before) the starter when it gets hot will the solenoid will not move it and you have to wait for the car to cool off and the starter works again. For some reason I am leaning towards this area as the potential problem. "
 

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My '02 RS did this exact same thing the last time I started it. The battery is constantly connected to a trickle charger to keep the charge up and I'd disconnected it prior to starting. The outside temperature was about 25 degrees F. I hit the starter and the engine turned over a few times and then made the noise you described as the engine quit turning over.

I thought it was a strange noise but I tried again, this time opening the throttle slightly and the bike lit right up and ran just fine.

I don't think it's anything to worry about as I've had other mechanical appliances make strange noises from time to time. You should hear the strange noises emitted by my big block Chevy engine with high speed starter motor attached.
 

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Chris_in_NY said:
I had this thought from my brother .. any thoughts on this?

"I think the starting system on these bmw's is same as a car. Sometimes on a car, the starter motor does not engage or disengage properly. I think the starter spins the flywheel. ..."
Hi Chris,

I suspect your sprag clutch like we talked about in PM's. I understand it being something like the freewheel gear in a bicycle rear wheel. When you pedal fast enough to push the bicycle, it's engaged. But when coasting, it's disengaged. So, for your MC when your starter motor is spinning faster than your engine, it's engaged but otherwise not. This is different than the "Bendix" of a cage starter where a gear is thrown out to engage teeth on the flywheel. If the starter sprag clutch re-engages after the engine catches and the starter motor has stopped, you would hear a big metallic clash.

Here's a URL about an F650 with a problem there that sounds something like yours: http://faq.f650.com/FAQs/SpragClutchFAQ.htm Here's one for a K100 (which works like a K1200RS): http://www.ibmwr.org/ktech/sprag-clutch.shtml - but this refers to fixing a problem when the clutch simply doesn't engage and the starter motor spins without turning the engine - not what's happening with your bike.

Betcha a beer when I meet you that Tony at Max will tell you it's the sprag clutch :) And that would be a warranty issue. :bmw:
 

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Discussion Starter · #12 ·
engine flooding??

this could be it. would such an event flood the engine? the second piece of this puzzle is that if i try to start the bike afterwards, it takes way longer than normal with a lot of presisng the started button and playing with the throttle
 

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Chris_in_NY said:
I had this thought from my brother .. any thoughts on this?

"I think the starting system on these bmw's is same as a car. "
No it's not. K-bikes have a sprag clutch, not a bendix.

Bob.
 

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Chris_in_NY said:
this could be it. would such an event flood the engine? the second piece of this puzzle is that if i try to start the bike afterwards, it takes way longer than normal with a lot of presisng the started button and playing with the throttle
That's a possibility. K engines are known to carbon up if started and run just a bit then shut down. Doesn't happen if it's done once between rides, but does if the bike is started and run for a short time more than once between rides. Makes the bike is hard to start - sometimes the plugs have to be removed and carbon deposits cleaned.

Those carbon deposits would have come from a too rich condition that didn't get a chance to burn off. Sounds like flooding to me and could account for the hard start after stalling.
 

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one other thing you should do when starting in cold weather is to disengage the clutch to isolate the trans from the motor....cold gear oil will make your starter work harder on starts.....
 

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what a asome day in the northeast.....took the gt out for a ride......lots of sand...and lots of shoppers on cells....sure notice a lot more in the bike...shes back under the covers now....with a smile..
 

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you should never have to touch the throttle on start up...if you do than there is something wrong.....or maybe you just think you have to....its one thing to do that with carbs....but never fi...
 

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You will notice it is only when cold that the starter kicks back and doesn't do it again after it warms up. When it sets for a couple days or more it gets really really cold natured and that is when you hear it. The noise happens when you let off the starter before the engine starts but dies instead and then the big TANG noise comes. My 04GT does it and it sounds like the engine kicking backwards before the starter disengages. I think it inhearant to this bike so I really don't think much about it other that my carbed turbo ZRX will fire up the 1st time in 15 degree weather and stay running and the beemer takes about 5 tries to stay running.
Later == Bobby
 

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Discussion Starter · #19 ·
will have to wait and see ...

hopefully the weather holds here in NY so the bike can get picked up on Wednesday and looked at. Per the messages, the bike has been in neutral each time this has occured. Also, the one day the weather was in the 40's and the other day it was in the 50's, so I don't think it's a cold weather type of thing. Also, the one time it happend, it took about 20 minutes to get the bike started. i will be pretty disappointed if it turns out this is an inherant issue with the bike. when it does happen, it truley sounds like something in the engine has broken, and by this i mean engine parts yielding, cracking or snapping ... ie. it's a nasty, metallic noise
 

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Discussion Starter · #20 ·
noise identifed

bmw mechanic says noise is a starter clutch assy/starter problem ... he's waiting on feedback from bmw before proceeding ... so i don't know what the feedback from bmw part means ....
 
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