petcock noise

[Dave_17954]

Ok I have a whistling noise that seems to come from the petcock or down in that area. I put on a new factory suzuki petcock last summer. Is there any test I can do to eliminate the petcock from making the noise? This noise has always been there and its just getting annoying. It sounds the worst at around 3,000 rpm. The bike only makes this noise when going down the road. I've had it up on the center stand and ran it through the gears and cant duplicate it also just revving the motor to 3,000 rpm sitting still and i cant duplicate it. Have eliminated the tach/speedo cable as the source also the front wheel. The bike is running fine and the petcock is working fine in all positons. Its made this sound before my rebuild and has continued since my latest rebuild. I know noise can travel in aluminum but it definately sounds like right around the petcock area. I checked the screws on the back and they are all tight.

 

[frosty5011]

Did you maybe re-route the hoses differently when you changed it out? Maybe they are what's vibrating / whistling in the wind when you ride.

I haven't run across a whistling petcock yet, but I guess it is possible.

:-\\\ <-- Smiley, goes by the name of Petcock!

 

[Dave_17954]

I was trying to think of a sound that was similar and all I can come up with is like a teapot whistling. You really dont hear it til around 2500rpm then gets louder at 3000 rpm then fades again when you hit about 4,000 rpm. doesnt matter the gear your in. All the petcock lines are routed as they should be. And the noise is very noticeable. I had a motorcycle mechanic ride my bike and you can definately hear it as he was coming towards me. He says its harmonic engine noise and I asked why cant you hear it sitting still and revving the motor or on the center stand in gear as i mentioned before......

 

[1978GS1000custom]

check the vacuum line from the fuel valve to the carbs that opens the valve. also check the other vacuum lines from the carbs to the air box. its sounds like what you describe when theirs a pin hole leak.

 

[Dave_17954]

I've replaced the fuel line, vacuum line and vent line with new during my last rebuild. I checked the clamps form carbs to air box and those are all snug. also orings on carb boots are all new. gonna try some detective work today...

 

[MelodicMetalGod]

I would agree that it sounds more like a "wind over a bottle" type situation. It seems unlikely that a noise related to engine speed would not manifest unless the bike was in motion.

I'll be curious to see what the culprit turns out to be.

Best of luck!

 

[Dave_17954]

took the horn off this morning and tried that but the noise is still there. Was thinking the of trying the motor stethoscope on some back road somewheres to see if i could pin it down. Dont want anyone seeing me looking like an idiot....... One thing I havent tried is driving it down the road at 3000 rpm and pulling in the clutch that way I could still be coasting and see if the noise is there. Maybe hold the clutch in and keep it revved up and let it coast at speed. Sounds like a road trip in the making here.

 

[Larry D]

If that's the bike next to your name, maybe it's the windshield ? I have a rattling on my bike. It took a few days until I figured out in is the front fender where it's riveted. It doesn't bother me know I know what it is........

 

[Macguyver]

Silly question

Silly question

A customer brought in a car and asked me to take it for a test drive and see if I could figure out what was making the odd squeeling sound he heard going down the road. Turns out it was a defective "Deer Whistle" he had installed to prevent deer strikes!!!

I assume this isn't the case here though. My best guess would be wind driven harmonics, get an air blower and blow air at your bike from the front to see if you can duplicate the whistle, if so, it should be easy enough to track down then. If not, I would make sure all of the electronics are secure and wires are covered with split loom to hold them to the frame, then go for a cruise.

Just my 2 cents, best of luck.

 

[Steve]

I was thinking wind whistle, too, but he said it happens at the same rpm, regardless of what gear/road speed he is travelling.

I have heard of whistles coming from open handlebar ends and pockets under clutch levers, and was going to suggest one of those until he said that road speed does not matter, only engine rpm.

.

 

[Dave8338]

Are the little rubber fin blocks still mounted on the engine? I removed them while painting a friends engine and he wanted them left out until...he rode the bike and there was a definite reverb/harmonic that only went away once the damper blocks were reinstalled. :-s

 

[Dave_17954]

I did remove the windshield to eliminate that. Heres what I did this afternoon. Got it up to speed at around 3,000-3500 rpm where it was whining/whistling good then pulled in the clutch and kept the revs up and there was no whine/whistle sound. Could this be a clutch whining sound? this is not the original clutch that came with this cycle. The po said the original was slipping and I got a complete clutch/basket/bearings and everything off ebay and Ive been running this clutch ever since ive had the bike and its always made this sound. seems a little noisier than it did last year this time. I measured the disc and looked them over after my last rebuild and there is plenty of wear left on the disc and the bearings look fine. It doesnt slip at all. I notice when I get up to say 55 mph and around 4,000-4,500 rpm the engine sounds really smooth and quiet. Could this replacement clutch I got last year be making this noise? Ive never had one to compare it to. I noticed the springs on the back of the clutch drive gear plate are loose in there little housings are they supposed to be loose in there? Once again nothing to compare them to. It shifts good and the clutch doesnt slip on me at all but could these disc make a whining/whistling/squealing noise if they say get worn or glazed or something to that effect? When I pull the clutch in the noise goes away. this is whats leaning me towards this area. and like i said earlier i know noise can travel in aluminum but ive never done a "test" with the clutch until today. My clutch doesnt rattle at all and I know the clutch nut is torqued to spec and the washer is bent holding it in place. I did just pick up some newer rubbers for the fins this evening have yet to try them tho and I do have 2 missing on the right side of the motor all the rest are in but i know some of them are hard. the ones i picked up are in good shape but will have to wait until tomorrow to try.

 

[Dave_17954]

i swapped out all the fin blocks plus added the 2 I had missing noise is still there. I'm thinking clutch area for sure. Nothing to serious as its been doing this for at least year other than annoying. Might wait til I can do a basket repair with new springs on the back plate and a few rainy days. maybe save up for a new set of disc to in the mean time.