Author Topic: 95 K11LT engine kerthunk (Read 16219 times)

ICBMW · « **on:** June 20, 2014, 05:37:07 PM »

After a hot day in traffic, engine has a new noise. Idles OK but periodically goes kerthunk which interrupts idling for a sec and then it returns to normal idling. It's intermittent and it idles and then goes thunk or kerthunk again and then back to idling. I could record the idle on Soundcloud if you care to listen or if my description is obtuse, just let me know. Thanks in advance for your help.

Zipster · « **Reply #1 on:** June 20, 2014, 05:49:31 PM »

What about a video? Would that capture the sound?

ICBMW · « **Reply #2 on:** June 20, 2014, 08:16:25 PM »

Yes. I'll do that in a few. Thanks.

jacksdad1963 · « **Reply #3 on:** June 21, 2014, 07:07:56 PM »

Have you removed the sidestand lift up system?
Reason I'm asking, my K1100LT has had the whole lot removed, I can start the bike with the stand down, without pulling in the clutch lever, or when in gear, by pulling in the lever. I can even start it in gear, on the centre stand, with a few jerks and bangs from the drivetrain!
BUT...after riding a few feet, I always get a sort of 'clang' noise from under the Clutch arm. Like a sort of noise you'd get if you kicked up the sidestand against the exhaust....very strange! :dunno2:

Scott_ · « **Reply #4 on:** June 21, 2014, 07:19:09 PM »

Quote from: jacksdad1963 on June 21, 2014, 07:07:56 PM

Have you removed the sidestand lift up system?

I presume you are talking about the electrical ignition interlock switch?
Some owners have this switch bypassed or outright removed, as it can be an overlooked trouble-shooting nightmare sometimes.

The early K-bikes had a mechanical mechanism that would retract the side stand when the clutch lever was pulled in. This was replaced with the electrical switch on the 1100's.

Zipster · « **Reply #5 on:** June 22, 2014, 03:12:05 AM »

Quote from: jacksdad1963 on June 21, 2014, 07:07:56 PM

BUT...after riding a few feet, I always get a sort of 'clang' noise from under the Clutch arm. Like a sort of noise you'd get if you kicked up the sidestand against the exhaust....very strange! :dunno2:

That'll be your ABS engaging!

jacksdad1963 · « **Reply #6 on:** June 22, 2014, 07:02:47 AM »

The ABS ! :clap:
Its been driving me crazy, just cannot find anything but now I know, I can forget about it. :2thumbup:

ICBMW · « **Reply #7 on:** June 22, 2014, 01:42:41 PM »

It's not the ABS clunk. It's during idling. Here's my bike idling (clip one didn't have a clunk)

Here's one with one kerthunk (19/20 second mark)

Here's another one that was unsuccessful

Forgive the dirtiness of the bike. Maybe it was bad gas or maybe it doesn't like the top 93 octane gas. I don't know.

I'll try to get a better one. Worst video ever. Super boring.

Zipster · « **Reply #8 on:** June 22, 2014, 02:36:07 PM »

(Vid 2 approx 19 secs) That certainly sounds mechanical but I've no idea what it was! I knew your clunk wasn't the ABS engaging - I was referring to Mikes query!

Elipten · « **Reply #9 on:** June 22, 2014, 03:14:17 PM »

Have you pulled alternator and checked monkey nuts? I don't have any experience with this model of kbike, but area and overall sound makes me consider it. The monkey nuts get old and shrink and then metal on metal sounds occur.

Scott_ · « **Reply #10 on:** June 22, 2014, 05:45:42 PM »

How many miles on it. Dino oil or synthetic.

Follow my train of thought here, and just my opinion........
These bikes have been known sometimes to have the sprauge clutch stick and not allow the starter to engage the engine. The sprauge assy turns as the motor turns, possibly one of the sprauge fingers is hanging up and occasionally "catching" when it shouldn't.
The gear assy is lubricated by the motor oil inside the intermediate housing, but is not submerged in oil.

Maybe get some extra detergent cleaner(seafoam or similar) for the engine oil and run it for a bit to help clean it up?

Opinions of others here?

Elipten · « **Reply #11 on:** June 22, 2014, 06:20:51 PM »

That would have been my next guess given the location of the sound. When I replaced the monkey nuts on my K75 it was amazing how many sounds went away, how much quieter the bike became and smoother.

If sprague issue best to jump on it sooner than latter.

ICBMW · « **Reply #12 on:** June 23, 2014, 11:06:46 AM »

I added some of this and lowered the octane of the gas and have run it hard and the idle seems to have smoothed out. I'll see if it stays that way. I didn't put any additive into the oil. Should I! I love Seafoam.

Scott_ · « **Reply #13 on:** June 23, 2014, 05:50:05 PM »

I'd at least plan on some seafoam in the oil when you are about within 50-100miles of your next oil change.

Just remember to not over fill the crankcase. If you are already at the max line in the sight glass, you may want to draw some off, then top it off with some seafoam.

jacksdad1963 · « **Reply #14 on:** June 23, 2014, 06:05:11 PM »

Now I'm lost again....
It does it when I set off from standstill, I do a few feet and then it 'clunks' like something being dropped onto a tin can, bouncing then hitting a second time, like an echo.
Its defo coming from under the trans/clutch lever area. I tried to record it but the engine sound is too loud but I'll try again with the camera on the ground :2thumbup:

Zipster · « **Reply #15 on:** June 23, 2014, 07:14:39 PM »

Quote from: jacksdad1963 on June 23, 2014, 06:05:11 PM

Now I'm lost again....
It does it when I set off from standstill, I do a few feet and then it 'clunks' like something being dropped onto a tin can, bouncing then hitting a second time, like an echo.
Its defo coming from under the trans/clutch lever area. I tried to record it but the engine sound is too loud but I'll try again with the camera on the ground :2thumbup:

Mike, I'm pretty sure that's your ABS engaging. Does it happen when the ABS lights go out? If so then that's what you have. At the moment mine is not doing that and I'm mighty hacked off about it!!

Scott_ · « **Reply #16 on:** June 23, 2014, 07:15:04 PM »

Quote from: jacksdad1963 on June 23, 2014, 06:05:11 PM

Now I'm lost again....
It does it when I set off from standstill, I do a few feet and then it 'clunks' like something being dropped onto a tin can, bouncing then hitting a second time, like an echo.
Its defo coming from under the trans/clutch lever area. I tried to record it but the engine sound is too loud but I'll try again with the camera on the ground :2thumbup:

Mine doesn't do it at every "set off from standstill" but probably every 3rd, but the ABS pump system does complete a self test cycle. It isn't an easy sound to safely try and record either.......

Grim · « **Reply #17 on:** June 23, 2014, 08:03:21 PM »

It's a slight miss and it's banging the gears and sprag. The crank doesn't connect directly to clutch. The end of the crank is below the alternator. It drives an intermediate gear that the clutch bolts on and then gear drives the alternator. See attached cutaway. The noise is the lash between the gears. Mine does it bad cold. I'm about to have the injectors cleaned and replace the throttle body bushings that are prone to failing at this age then balance the throttle bodies to cure it .

ICBMW · « **Reply #18 on:** June 23, 2014, 11:41:14 PM »

Thank you so much, Grim. The Ks have so many funny clinks, clunks, taps, and tinks.

johnny · « **Reply #19 on:** June 24, 2014, 04:20:11 AM »

i recommend wearing ear plugs when riding and messing with your motobricks... you will getts a lotts more riding in and a lotts less fussing...

j o

grant71 · « **Reply #20 on:** June 24, 2014, 04:59:12 AM »

Hi. What and where are " monkey nuts " ?

Scott_ · « **Reply #21 on:** June 24, 2014, 06:47:20 AM »

Quote from: grant71 on June 24, 2014, 04:59:12 AM

Hi. What and where are " monkey nuts " ?

Between his legs........ :hehehe :hehehe

sorry I couldn't resist......

part #9 X qty 3 bmw # 12 31 1 464 877 at about $7 each.

Grim · « **Reply #22 on:** July 02, 2014, 05:03:36 PM »

I believe I just cured the idle complaints on mine. I found a split throttle body boot (BMW calls it a bushing) on #3. Mine did the "kerlunk" noise pretty frequently hot or cold, did not matter. I just finished putting everything back together haven't even had a chance to take it for a proper test ride. It hasn't done it once since I replaced the boots just idling it to make sure I didn't have any leaks.

Seems to fire off better as well. My idle was at 1150 ish before working on it and now it seems to have dropped back you 950-1000 where it's suppose to be and I have not made any adjustments. I also found a couple other vacuum leaks (all before the throttle bodies so wouldn't have caused idle issues), bad fuel lines and a bad crank case breather hose.

List of parts used:
8 clamp from Grainger (1) 5czd8
36 in of high pressure fuel injection hose
1 crank case vent hose 111 151 461 835
4 ORings for throttle pedestals 116 114 651 69
4 bushing (boot) 116 114 617 39
Vid of what I found:

552255 · « **Reply #23 on:** July 03, 2014, 09:12:19 AM »

Quote

Grim: I did the exact thing and my bike is running much better.

Quote

8 clamp from Grainger (1) 5czd8
36 in of high pressure fuel injection hose
1 crank case vent hose 111 151 461 835
4 ORings for throttle pedestals 116 114 651 69
4 bushing (boot) 116 114 617 39

I'd only add that the lower 7"x1" w/90d bend, fuel hose is worth ordering to do the job, i couldn't get the straight hose to make that bend.
Check all vacuum lines for leaks (before ordering parts), and thoroughly clean out the throttle bodies etc. I also replaced the rubber vacuum caps ($1.70) as well...2 out 4 bushings were split...

K75RT Keith · « **Reply #24 on:** July 03, 2014, 10:38:13 AM »

Instead of buying the bent hose, I used about 10" of FI grade hose and added the chrome/brass quick disconnects used on the R1150GS to both lines.

News:

Author Topic: 95 K11LT engine kerthunk (Read 16219 times)