1985 K100RS with 40K miles. Which of these noises are OK? All fluids changed recently (none of the noises are new)


or direct link
https://www.youtube.com/watch?v=VZe4dT8LRlk


1. Ticking: Injectors? Is this normal amount of ticking?

2. Whirring/Whining: (increases in volume and pitch with RPMs) Output Shaft? Alternator? Should I be concerned?

3. Suction: Tougher to hear in this video, but my fuel pump is getting pretty noisy these days. How loud is too loud?

Thanks in advanced

TRIceberg - I'm going to let someone more experienced comment on the ticking sound but it doesn't sound like its the injectors (which are on the opposite side of the bike to the camera shot).

The whirring/whining sounds normal to me (at least mine sounds the same)

I can't really hear it on the video but the fuel pumps are noisy and even more so as the fuel level drops in the tank giving them room to resonate in the air space. You should probably check the rubber mounting though.

88

The whirring sound or whine is due to the split gear on the output shaft, which is spring loaded between gear halves to eliminate backlash in that gear. That is normal (and annoying).

The tick could be two things. Number one, it could be the rubber dampers in the alternator cush drive are worn out. Second, and this would relate to the sucking sound, there might be a hose from the bottom of the tank to the top of the engine block right at the very front under the radiator, with a check valve on the hose somewhere. If there is any sort of hole or tear in the hose, or if it has simply broken off due to age, you will hear a ticking, sucking noise.

Another place to look would be the little elbow shaped hose running from the bottom rear of the plenum into the crank case. These things get hard from the heat (hey now, not like that!) and crack, allowing for a noisy vacuum leak.

Even better, you might have both leaks going.

Agree its the alternetor rubbers mine sounded similar when i removed the alternator could see why. flat and old. put new ones in ( used a bit of lithium grease to aid as its a swine to push alternator in with rubber friction) and noise all gone!! Now just glorious beemer whoosh. think they were about £20 all in from motorworks.
pete

I puller the alternator and the rubbers are a little worn compared to the new ones I've looked at online. I'll give some new ones a try.

The ticking is most prevalent at the fuel injector rail. I can even feel it when touching the rail. I know injectors can make this noise, but wasn't sure how loud was ok.

I'm glad the whirring is a common thing and not a large mechanical issue, but it is frustrating since it overpowers the sound of the exhaust. I suppose its just the charm of a K.

Thanks for the replies

TRIceberg wrote:

I'm glad the whirring is a common thing and not a large mechanical issue, but it is frustrating since it overpowers the sound of the exhaust. I suppose its just the charm of a K.

Thanks for the replies

Get a real nice loud Zorst....problem solved.....you will find most sound like that....I have a staintune...:O)

In my experience, the ticking from the injectors can be fairly present normally. The whirring is normal for the bike. The suction / chuffing sound could be a few things. I saw a couple people above mention the alternator cush drive and some hoses as possibilities. It could also be a small exhaust leak.

I bought a '92 k100 a few months ago and it had a sucking / chuffing sound similar to that. I went through and checked everything I could and was stumped. Then I did a compression test. Turned out there was no compression on the 1st cylinder. The chuffing sound was the compression escaping somewhere. And it ran and idled alright. Rather than repair it, I just replaced the whole engine with a lower-mileage '91 engine for a lot cheaper.

Your bike seems to sound fine and rev fine, so I doubt that's it, but just for poops'n'giggles, try a compression test.

Sounds normal to me Ticking is the injectors. The whir is just normal k100. I can't hear a sucking noise though?