More Kbike Clunks in the Night! (or WTF is that Noise!!!)

[Opus]

Hi Gang.

Got an issue that I need help with. I have a loud clunking noise coming from around cyl.#2. It is intermittent and happens hot or cold.
I noted it after a late spring ride and did not get a chance to look at it until now. (have not had time to ride)
The noise is all across the RPM range.

Things I have done:
Swapped out CPU.
Swapped out Plug Wires
Replaced Plugs
Cleaned Coils & Connections
Drained the gas and put fresh gas in tank. (no water found in old gas)
Run some Injector Cleaner through the system.
Replaced Air Filter & cleaned filter box.
Replaced fuel lines.

I'm hoping that someone out there has see this problem before and can suggest a course of action that will help get to the root problem.
Any Help will be gladly accepted.

Here is the video I shot on my phone. You can hear the clunking and missing very clearly.



Thanks in advance!

[johnny]

your list of things you have done... didnt see ride it hard and ride it often... thats generally what motobricks need to be happy...

anyway... sounds normal to me... what are the rpms during that movie...

j o

[Opus]

your list of things you have done... didnt see ride it hard and ride it often... thats generally what motobricks need to be happy...

anyway... sounds normal to me... what are the rpms during that movie...

j o

Hi Johnny.

Did a hard ride about 2 weeks ago. That is when I found out that my fuel lines were rotted out and I was leaking gas all over. LOL
The problem had started before that ride and is getting worse.
RPMs were between 950  to 1100 at idle. Miss/clunking sound happens no matter the RPM range.

T.

[Grim]

That is the exact same noise mine was making. Number 2 boot (BMW calls it bushing) was torn and it was sucking in air past the throttle.  New boots and had my injectors cleaned and tested and has completely cured it. I think it's a little different set up on a 100 but I bet you find a vac leak

[Opus]

That is the exact same noise mine was making. Number 2 boot (BMW calls it bushing) was torn and it was sucking in air past the throttle.  New boots and had my injectors cleaned and tested and has completely cured it. I think it's a little different set up on a 100 but I bet you find a vac leak

Will give a good look see in the morning when I have some light and the skeeters are not trying to drain all my blood.

Thanks

[Opus]

Update:
I used some compressed air to spray around the #2 air intake and noted that the RPM's did pick up when air was forced near it. But I also found that if I spray around the injector for #2 that the RPM pickup is more dramatic than when sprayed around the air intake. Beginning to think problem is around injector or O rings.

Any thoughts on this?
 :dunno2:

[Opus]

Got some Carb-Cleaner and tested around #2 Cyl. intake to cyl. head and injector. motor ran smooth when cleaner sprayed at base of injector/lower rubber flange area.

FYI to Riders local to Memphis Tn.
Local BMW Dealer not stocking Injector O-Rings for 88 model K100 Bikes anymore. (per Parts Dept.)
Can get Replacements @ NAPA (PN FPG ES70599) for $3.45 for a set of 4.

Going to pull rail & injectors in the morning and also check the lower intake flange for damage in the morning.
Will update findings in the morning.

Thanks for the help & suggestions gang!

[ReneZ]

As you said you had the same issues at the injector you might as well renew those o-rings