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'07 900 custom belt squeal and ping/twang...

2K views 8 replies 6 participants last post by  DoomCrewInc 
#1 ·
Hi folks, need some advice here...about 3 weeks ago my '07 900 custom developed a "pinging/knocking" type sound right around the same time that I noticed the belt became squeaky. I've got just over 30,000km on the bike, it's been running great since I bought about 4k ago. The squeak, I gather, is a common issue among Vulcan owners. It's the ping/knock sound that has me worried. It's coming from the front pulley area, only when the belt is under tension, in either forward or reverse direction. Sound disappears completely when belt is not tensioned, and comes back once I've reached 6-7mm of deflection. The pulley doesn't feel loose at all, and is showing no signs of abnormal wear. The belt also shows no signs of wear or damage.

Has anybody experienced this before? Could the squeak and knock be related? Wanted to check here before I spend the $500 and change on a new belt :(

I should also mention, I'm a first year rider, mechanically inclined, but by no means a mechanic so I'm still learning about my bike by doing my own maintenance / repairs. So bear with me if I come across a little newby-ish. Thanks
 
#3 ·
Belts rarely go bad and usually only need replacing if broke or damaged I some way. To my knowledge anyways! Did you install a rear overdrive pulley by chance? The belt squeak can usually by associated with that. Some claim to have gotten rid of it, some of us (me included) just deal with the squeak. Can't speak to the other noises you are hearing, no known issues I can think of for that.
 
#4 ·
The pulleys are stock, as far as I know. If it was just the squeak, I could live with it. But the knock (almost sounds like the belt teeth are compressing while travelling the front pulley and then as they exit the pulley they're snapping back to their original position). I'm able to reproduce the sound from time to time simply by applying a small amount of downward force - about midway between the pulleys - to the belt while it's up on the lift, with no rotation of the pulley at all. Has me a little confused
 
#5 ·
My guess is your belt is too loose....Mine was very loose the sounds it made drove me nuts, it chirped, squeaked, rattled..i tightened it up. Took for a 100 mile ride today it was like a new bike.....i see now why people love this bike so much...i need to fine tune my belt just a tad more, it made a world of difference.
 
#7 ·
One thing I have figured out about these bikes is kawi runs the belts tight from the factory for a reason....if these belts are loose just a hair they make all sorts of noises...I know its a pain but my advice is tighten belt test it retighten test it retighten some more....
 
#8 ·
Oh my, our wonderful belts.

My belt was very tight from the factory (they supposedly set it at the tightest part of spec, 1.5mm), and it started squealing. Had it loosened just a bit at the 600 mile first service, and it got better. Eventually, it stopped altogether. After several thousand miles, had both pulleys installed, and it started chirping. Loosened it a little, and the chirp went away. Then it started chirping again and seemed very tight after riding. Tested it and it was 3mm deflection in the window with 10lbs pressure just in front of the swing arm. Right in the middle of spec. Cleaned it and put some dry silicone on it. No chirp. 500 miles later it started chirping again. Put some dry silicone on it it. No chirp. As of today, no chirp in over 500 miles since the last dry silicone treatment. Factory says don't spray anything on the belt. My KEL Dry silicone says it doesn't attract dirt, and a maintenance guy said its fine, so I've used it (just twice).

Anyone want to write a book on the philosophy of belt tension?

BTW, my guess would be that your belt, at 6-7mm deflection (did you measure it per the service manual in the window with pressure just in front of the swingarm?), is too loose, and the ping/knock you hear might be the belt occasionally slipping a tooth. My best guess would have been that 6-7mm wouldn't be loose enough to do that, however.

For what it's worth,
Dan
 
#9 ·
I agree that it could possibly be skipping teeth. SneakyP, I know you said that the front pulley doesn't appear to be loose, but did you put a torque wrench on the pulley retaining nut and check it? I ask because I had a horrible sound coming from my front pulley area once that was so bad when I had a mechanic buddy ride it and listen he told me not to ride it and have the motor pulled apart to check the tranny or I was risking catastrophic failure. After a bit of looking around online I read somewhere to check the pulley nut's torque. Everything looked ok. Pulley looked and felt tight. But it was loose. Not much. But loose. Matter of fact, when I put it to the correct torque, it only turned about 1/8 of a turn. Noise was gone. Hasn't returned in over 8,000 miles. We all know that the belts are very tight from factory. Some say by design. Some disagree with how tight it is (myself included). All I know is when I had my rear tire replaced, I got my bike back with the belt tighter than it was before the change. About 1000 miles later and the noise showed up. Did the extremely tight belt cause the pulley nut to come loose? I don't know for sure, but I do know that after I retorqued the nut, I had the belt tension loosened and the nut is still at proper torque and have had zero problems since.
 
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