Thwacking noise when in neutral

[Laitch]

Well I recorded it on video and have uploaded it to YouTube

Thanks for the audio file. Not worrying is the way to go.  :2thumbup:

[restinthesun]

Good to hear I'm not the only one nuts enough to worry about this. Took Laitch's advice but still annoying. Not tech savvy enough to understand exactly what WMAX351 just detailed there, but sounds like she'll ride for a while yet before I should worry.  :2thumbup: [size=78%] [/size]

[Grim]

Because of how these motors are built where the crank drives a gear to get to the clutch there is a little extra slack BMW put a spring in there to help a little.  What you may be hearing is a bit of slamming of gears. Pushing the clutch may be adding a little drag.

Things to check.
#1 Vacuum leaks. I've had to replace all the vacuum line and on 1100 there is a boot that the throttle bodies sit on. They were cracked in the folds.

# valve lash.

 Check that stuff then balance the throttle bodies.

[restinthesun]

Thanks for the checklist, Grim. Will see about getting those assessed.


After the first few rides of the season, she still makes the noise – soft at first and louder as it warms up – but realized when I pull in/release the clutch it doesn't just stop and start... the 'thwacking' in question speeds up about double time right when the clutch starts to release if I do it slowly... then the thwacking slows to the usual pace as it's fully released. 


Others do the same? Any help in deducing the issue?    :dunno2:

[Laitch]

Any help in deducing the issue? 

If you have read this thread, you'll get the idea that to isolate this sound might take some time, mechanical effort and and maybe a little expense. There are some excellent illustrations and sound files provided in it as well as astute observations, explanations and tips by some of the contributors. Gryph explains the technique used to eliminate a noise in his engine. goneape provides useful video and observations of his experience.

Deciding where you'll start with all this is a task only you can do.

[restinthesun]

Copy that, Laitch. I read the first few paragraphs of that thread and realized the problem weren't the same...


"Pulling in the clutch makes no difference at all."


...was just offering another observation to what seems a most vexing problem...  :euro

[Laitch]

Copy that, Laitch. I read the first few paragraphs of that thread and realized the problem weren't the same...
"Pulling in the clutch makes no difference at all."

The whole thread covers the common irritating noise sources in these bikes and various attempts at quelling them. Reading all of it has the potential to increase mechanical knowledge in general.

If the noise has changed from the first video you posted, post another. Good luck.

[johnny]

greetings. 

the only motobricks i have heard that did not sound like that were the ones not running...

trailbrake to the apex and whack that throttle... ride that motobrick till it wont move...

wear good earplugs and keep it revved and the only noise you gonna hear is the yeeeeeeeehaaaaaaaa between your ears...

make sure your aaa is paid up...

getts some techron in there and getts on your spaceman suit and commence to motobricking...

j o

[Snowman]

The older i get, the less i worry about odd noises. This applies to myself and my bike. In this case I hear a brick motor like any other and you may spend countless hours trying to figure it out and never find it. Take that time, strap on your helmet and go ride. My 1100 has had noises come and go, it is just the running in process of smoothing gears and setting clearances.

[restinthesun]

I had taken Laitch's original advice but popped on my radar again when I saw others wondering wtf... got distracted by the pot of gold when I should just be admiring the purdy skies as they fly by...