Crazy High Pitch

Wow! Started my bike yesterday (the bike that needs the carbs rebuilt) and heard really loud high pitched sound. It started as soon as I put it into first and started moving and then never stopped until the engine was turned off. Went riding later in the day and the same thing happened. I am about to start work on this bike and would like to get everything fixed in a couple of months.

What might cause that sound? It is deafening.

 

Does it make the sound while you're stationary with the engine running or only when the bike is moving? Does it change pitch with engine speed or road speed?

 

The pitch stays the same no matter what speed. It only starts when the bike starts moving for the first time but it is as little as 5 miles per hour. It does get louder the faster that you go but once it is loud it is loud for good. If I remember right, it even keeps going when you stop.

 

Tach or speedo cable or the instrument itself, I'll bet on it. When the original tach (NOT the cable, I'm positive) on my '83 died, it was SCREAMING so loud people mowing their lawns stopped and looked up.

It COULD be something deeper, like maybe that "oil separator" thingie in the clutch housing but I don't know if that bike has that. Make sure it's not an external peripheral like the tach or speedo or something goofy before you get too involved.

 

Just went for a longer ride. Not too long. Not licensed, titled or insured yet. But, you were right. I took my son and had him walk beside the bike. We even turned it off and pushed it -- it made the noise. It is the speedometer!!! Wow! Thanks for the info. It jumps around like crazy. I guess this means I need a new one, eh?

 

Jon, may just need to lube cabel, assuming it is a mechanical speedo running off of front wheel. if so, give that a try.

 

I will do it. Am waiting on a service manual. Do they cover how to do that too? It would seem like a simple task but I don't want to do it wrong.

 

Jon, if it is like my 650, the cable screws into the bottom of the speedo housing. just unscrew cable & put the lube in the end of the cable let her sit for a bit & reconnect. i had this problem on my tach, did the same thing & problem went away. if it is coming from inside the speedo housing i am not sure what you need to do there. try the lube deal first & if doen't work post that here & someone will be able to help with suggestions.
good luck
Gregg

 

Thanks Gregg... Any particular type of lube?

 

It's a mechanical cable attached with a screw-on ferrule at the top (on the back of the speedo) and either an identical screw collar or a slip-fit arrangement with a set screw at the bottom. I believe if you disconnect it at the bottom you will be able to extract the inner cable; clean it and lube with motor oil or a good automotive spray lube like Tri-Flo.

DO NOT USE WD40 for anything except to spray on the outside of metal to protect it. DO NOT use it to lubricate cables or controls, it gums up after time.

I just posted a close up pic of the guts of a Yamaha speedo here http://xjbikes.com/Forums/viewtopic/t=15075.html mine are in a "cluster" that can be taken apart, some are in "cans" that have to be cut apart but they all work about the same. If it's the speedo itself that's screeching, you're better off to replace it. They go for cheap on eBay all the time.

 

Awesome... I will do it and see how it goes. Thanks guys.

 

It could be the bearing at the input to the speedometer, but it's more likely to be the cable. It's making noise, then binds and jumps causing the needle to bounce. Since it's jumping rather than breaking it'll be sticking nearer the speedometer.

I'd pull the cable and sheath off the bike, disassemble and blow out with compressed air. If the cable is frayed replace it, otherwise lube and reassemble.

 

When my tach died screaming it was (the input bearing.) I pulled it out and lubed it and it locked altogether, which means the bearing was toast.

Carl's right though, it is more likely the cable.

 

I will check it all. Interesting. When I got fast enough the squeel would stutter. Sounds like binding. Thanks again. I will let you all know what fixes it.

 

I had it on my goldwing. A lube didn't fix, but a new cable did.

I had it on my current bike ('82 650 RJ). Good cable lube fixed it.

By the way, a faring or sheild will magnifiy the sound!

 

No faring. Hope to buy one someday. Much more to do first.