1993 K1100RS, Just got its safety, ready to license, then KNOCK, another KNOCK!!!!

[dieselyoda]

Then it went KNOCK, KNOCK, KNOCK, KNOCK, KNOCK at idle!!!

Holy crap, I have almost 16 months of fighting this bike every step of the way from the day I got it, cheap. Just when I see the down-stroke to actually putting some miles on it, it starts to knock at idle. Only idle. The knock sure sounds deep and slow enough to be a connecting rod. I did tighten those? I think? It's only at idle though.

I can read pretty good when people type slowly. Nobody can see my lips move when I read because quite frankly, I don't have that many friends to hang out with.

The monkey nutz thing, read about, can't be. They were good, old, but good. Starter sprag, not likely, maybe? Noise is definitely in the rear of the engine so I'm rather smart and out think myself at times and think the knock is from the timing mechanism transferring down the crank. Not likely I think, no noise but good old chain noise.

Then it came to me. My brother with one of his German built cars phoned me and he had a horrific knock. I heard it on the phone and told him to get it towed to my shop. It turned out the serpentine belt blew about 1" section out of it and every time that section went over the belt tensioner, KNOCK!

My problem is that I can't find the serpentine belt and tensioner on this bike anywhere. Should I keep looking or just accept the fact that monkey nutz just blow up?

 

[98lee]

Two suggestions:

Does the knocking go away when you pull in the clutch?


Did you have the alternator out? Are you SURE, ABSOLUTELY SURE, that you got the drive fins of the alternator in the OPPOSITE slots of the monkey nuts to the engine drive fins or did you accidentally get them in the SAME slots? (guess which one is easier to do)

 

[AntonLargiader]

Check the vacuum balance between the TBs. If the engine is loping you can get a knock, some of them at least.

 

[dieselyoda]

UPDATE!!!! No, I didn't find the answer.

Yes, the knock is still there with the alternator laying on the floor. I even kicked the alternator like a mini-football to see if it makes any noise. It didn't complain.

The sync is dead on the money. The Beutch runs awesome. Noisy, but good.

Pull in the clutch, very slight change. In gear, little brake pre-load, no change.

In the troubleshooting process, I stripped the internal hex on one alternator bolt. Guess which one??? I dare you to get it wrong!

So I had to pull the starter to drill the bolt out. I bet you can't guess what the nose of the starter did! It's the same principle of pretending to pull the nose off a 4 year old child but, in this case, I did.

The noise is right at the back of the engine and only at idle. I can feel the knock in the frame. That gives me the "oh crap" feeling. Fortunately, all that time I spent looking for the serpentine belt and consequential missing chunk in the belt yielded very positive results. I'm positive it doesn't have a serpentine belt and I'm positive I'm screwed.

 

[dieselyoda]

Went backwards..............I can make the noise go away. I think no harm done??

I thought if it was engine noise, connecting rod, output shaft coupling gizmo, front chains/gears, in 5th gear rocking the bike back and forth should get me close to the noise. I really didn't hear anything to indicate much of anything.

I thought back to Anton's comment about engine "lope". Checked the throttle body sync, almost perfect. I wondered about the idle if it was too low.

The spec is 950 +/- 50 RPM. I'm at the low side, closer to 900. I boosted the idle to 1000, noise still there but way less.

I like very low idle as part of my riding habits. My Oilhead runs very close to 850 RPM. VERBOTTEN on the Oilhead forum but it likes it there and I like it there.

Now I'm thinking that a slight boost of the idle will make the noise go away and there really isn't anything wrong with the bike. Maybe just a loose nut holding the handlebars?

 

[dieselyoda]

Update, too simple for words to describe.

I got a bit fed up with this monster as the rear m/cyl that I have replaced TWICE started leaking again. No, I did not have the grub screw in too deep.

Took another crack at the noise while installing the THIRD rear m/cyl and while running the engine, I noticed faint movement in a spark plug wire. Almost vibrating. I grabbed it, bare handed, nope, didn't curl my hair. Took the vent cover off and watched in fascination as the spark plug wire moved. Pulled the wire off the plug, and the center porcelain all the way to the electrode came with it.

Replaced the plug, noise gone.

 

[Omega Man]

Nice

 

[dbrick]

 

[98lee]

Most FIXES on early Ks are relatively simple. It's finding the CAUSE that can sometimes be a real bitch!


Perserverance pays off again.

 

[dieselyoda]

Most FIXES on early Ks are relatively simple. It's finding the CAUSE that can sometimes be a real bitch!


Perserverance pays off again.

Not sure if that was a complement or an insinuation that I'm thick, like a Brick..............

I preach this with my mechanics, repeatedly, day in and day out, look for the simple solutions first.

 

[98lee]

Definitely a compliment!

Perserverance is what differentiates the good mechanics from the so so mechanics. So so mechanics give up after they check everything that SHOULD be causing the problem. Good mechanics keep looking for clues no matter how small (like a moving wire) that might lead them to the answer. Good job!