K75 Whine

[BUDDINGGEEZER]

I have a 1987 K75C that has a high pitch whine. I have read on a website where a K75 sounded like the Jetson's cartoon hover car, or a jet engine. Mine sounds very prominent like this. I have a 1987 K100LT that has a barely noticeable whine.

I have heard that the 75 whines more than the 100. This is a lot more.

Is this normal? Alternator bearings bad?

Ralph Sims

[cmartin]

K75's whine. Its the nature of the bike.

I have owned 3 K75's they all whined and had no major problems.
Very dependable bike.

[SHERIDESABEEMER]

Whine sounds like such a bad thing. Take your bike to a local club event, ask people if it sounds ok. Any proud owner can pick out a K75 riding by in a pack of 100 bikes.

[deilenberger]

I have a 1987 K75C that has a high pitch whine. I have read on a website where a K75 sounded like the Jetson's cartoon hover car, or a jet engine. Mine sounds very prominent like this. I have a 1987 K100LT that has a barely noticeable whine.

I have heard that the 75 whines more than the 100. This is a lot more.

Is this normal? Alternator bearings bad?

Ralph Sims

Ralph, your name seems familiar.

Is the whine you're hearing new to the bike, or are you new to the bike?

If you're new to the bike - it may be the normal K bike whine.

If not - and the noise has just appeared - alternator bearings are the first place I'd be looking. Also had someone who lost the bearing that holds the drive shaft for the alternator in place- that caused a lot of noise and eventually trashed the engine (wasn't worth opening it up to fix it - he had a good spare sitting there..)

If the bike is new to you - you might consider what others have suggested - find a few K owners and ask them to listen to it.

Best,

[cayuse60]

Mine wines, especially if you wind her up

[BUDDINGGEEZER]

The only problem I have in comparing the whine to other K bikes is this, The only ones I have ever seen (not counting new ones), I own. The K75 is new to me.

My 100 and 75 have the same type and pitch whine (jet turbine). Both seem to eminate from the alternator/ transmisson area. Both whines increase with engine speed. It's just the K75 is 2-3 times louder.

On the K100 the factory exhaust note overcomes the whine at 4000 rpm.
The K75 is just starting to overcome the exhaust note at 4000 rpm and it has a Staintune without the baffle.

Can the engine be run with the alternator removed to test?

Ralph Sims

[drharveys]

It ain't the Gewurtztramiener and it sure ain't that syrup they call Liebfraumilch -- the K-75 is, and always shall be, the finest German wine! And now that they've stopped production, it's the finest vintage wine!

Enjoy it for many miles to come! Much as I love my R1150RS, I do miss that K-75!

Harvey in San Luis del Norte

[deilenberger]

Can the engine be run with the alternator removed to test?

Ralph Sims

Ralph, can't see any reason why not. It will start and run at least for a while on just the battery.

[torags]

K75's whine. Its the nature of the bike.

I have owned 3 K75's they all whined and had no major problems.
Very dependable bike.

+1. I've had two. Vintage wine is a good metaphor.

Personally I liked it.

[BUDDINGGEEZER]

Am I on the right track?

I suspect that after the answers yall have given me, is the K75 whines more than the K100.

Is the reason the K75's input shaft has 2 balance weights to quell vibration and the K100 uses an absorber gear and rubber dampers?

This makes sense to me. I had thought the engines were basically the same and should sound alike, but there is a difference.

Thanks all
Ralph Sims

No longer budding, in full bloom.

[GILLY]

As an original owner, I can tell you it subsides somewhat with miles. I'd say mine was close to untolerable for the first 10,000 or so miles, bearable from then to maybe 40,000, and since then pretty tolerable, not as bothersome now. For the first 10,000, if I took a day trip, I'd still have that whine in my head when trying to sleep. THAT bad!
Gilly

[BUDDINGGEEZER]

Thanks everyone, I believe I have a healthy K75. With 37,800 on the clock she should run a good while.

We can spit on the fire, call in the dogs on this on.

Ralph Sims