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Message started by chzeckmate on 05/26/15 at 05:44:06

Title: "Shh" sound when decelerating
Post by chzeckmate on 05/26/15 at 05:44:06

Greetings everyone...I'm new to the forum and I've already done a search for this and found nothing that quite matched my issue so I'd like to put the question to the collective mind, if I may. I just got my S40 a month ago. It's a 2005 model with 11,064 miles (It had 10,300 when I got it). Until now it's been running and sounding perfect but now I'm getting a loud "Shh" sound when decelerating. It doesn't do this when the clutch is disengaged and I simply coast. It doesn't do this when accelerating either. I have no idea what could be causing it and it's very disturbing. I'm sorry to have to introduce myself this way but I'm very glad to be here and I'd really appreciate any advice/insight anyone might have. Thanks!

Title: Re: "Shh" sound when decelerating
Post by justin_o_guy2 on 05/26/15 at 05:58:28

Have you done anything to it?
Can you tell from which direction the sound is coming from?
Just 11,000 miles, kinda early for the cam chain... but,
When you pull the clutch in, engine drops to idle... chain slows down, centrifugal force diminishes.. maybe the noise is there under power, you just can't hear it over the exhaust?
If you try to find it sitting still, set a fan up, you rack it off sitting still a few times and the pipe will turn blue.. I know..

Might be time for valves, you're in the mileage for it. I doubt that is the noise, but it still might need done.
I like fresh batteries in stuff.. if yours is original equipment, at least check the water.

Title: Re: "Shh" sound when decelerating
Post by Dave on 05/26/15 at 06:00:57

When you close the throttle and decelerate you are making a big vacuum in the space between the intake valves and the butterfly in the front of the carb. The rubber intake manifold clamp for the carb could have an air leak, maybe the vacuum line for the petcock....check for anything that could cause a vacuum leak near the front of the carb.

Title: Re: "Shh" sound when decelerating
Post by chzeckmate on 05/26/15 at 06:24:33

5E4147405D5A6B5B6B53414D06340 wrote:

I've done the typical things one would do when buying a previously owned motorcycle. Changed oil, new battery, new plug, checked for loose nuts/bolts, etc. I haven't check the valve clearance yet but I know what ticking valves sound like and I've never hear valves make this sound before. I also haven't checked the cam chain tensioner but I'm familiar with what a bad tensioner sounds like when it's ovaling. This is definitely not making a knocking or ticking sound. As for the location of the sound, I can't get a bead on it. It sounds like it's coming from in front of me. As for the possibility that I might not be hearing the sound during acceleration over the exhaust, I don't think so. The exhaust is quite loud during decel. and I can hear this over that quite well.

7E45485F4E42595F444C415E2D0 wrote:

I will check for vacuum leaks but this sound is quite loud and I should mention that I have no noticeable loss of power and performance is in no way compromised. I would think that a leak like that would cause some noticeable difference in performance. Wouldn't you think so?

Title: Re: "Shh" sound when decelerating
Post by Srotag on 05/26/15 at 07:18:09

Check belt guard clearance. Mine was bent a little from the PO when I got it and made a similar noise, only on decel. 8-) 8-)

Title: Re: "Shh" sound when decelerating
Post by Serowbot on 05/26/15 at 07:31:26

Belt... if it does it with the clutch out, but stops with it in,... I'd say belt...
The engine drag is tugging the belt.
Try putting something on the belt...baby powder, vasoline, anything..
It won't fix it, but it will change the sound... then, you'll know it's belt noise..

Then, once you know, you can choose to try to silence it, or ignore it...

Title: Re: "Shh" sound when decelerating
Post by chzeckmate on 05/26/15 at 07:34:00

1A3B263D282E490 wrote:

Check belt guard clearance. Mine was bent a little from the PO when I got it and made a similar noise, only on decel. 8-) 8-)

I will definitely check that. I would think I'd have heard it before now unless maybe my tire pressure has changed or I've gained weight, which is entirely possible. I want to mention one other thing. I've noticed that when I decelerate my idle will go down to around 800 briefly and then come back up to proper idle speed between 1000 and 1200 rpm (I installed a tach when I got the bike). When the idle goes down to 800 briefly it sounds like it'd going to stall and sometimes it does. It's probably coincidence but this began happening a few days before I started hearing the "Shh" sound on decel.

Title: Re: "Shh" sound when decelerating
Post by youzguyz on 05/26/15 at 07:37:21

Check the front pulley as well. I had something similar. The PO had tightened the front pulley, but did not bend the tab over the nut to lock it in place.
The front pulley nut got loose. When I would accel, the pulley moved toward the engine, and no noise. When I decel, it would move away from then engine and rub against the pulley cover.

Title: Re: "Shh" sound when decelerating
Post by chzeckmate on 05/26/15 at 07:43:26

27312B24392B27245E0 wrote:

That's something I didn't look for during my initial inspection of the nuts/bolts. I didn't even think about it. I'll definitely get that cover off right away and check it!

Title: Re: "Shh" sound when decelerating
Post by chzeckmate on 05/26/15 at 08:14:05

Okay, I checked the front pulley and it's quite snug and the tab is bent over it as it should be. I also checked the belt guard for any signs of wear or contact from the belt and it's in perfect shape, not bent and not showing any obvious signs of rubbing. I did notice that the oil seemed a little low in the sight glass so I added a little and then rode a few miles to go buy some vaseline to put on the belt but the noise didn't present itself this time. I feel like that's just coincidence but maybe not. I've had a lot of bikes in my day and none ever made that "Shh" sound for being a little low on oil but then again none of them ever made that sound at all. This is my first belt drive so I'm inclined to still think belt. Could it be oil related?

Title: Re: "Shh" sound when decelerating
Post by justin_o_guy2 on 05/26/15 at 11:25:00

Dude, doggone if I have the answer, but I sure appreciate the way you explain things and respond to our best guesses instead of just ignoring them.

Title: Re: "Shh" sound when decelerating
Post by chzeckmate on 05/26/15 at 11:45:42

26393F3825221323132B39357E4C0 wrote:

Dude, doggone if I have the answer, but I sure appreciate the way you explain things and respond to our best guesses instead of just ignoring them.

You guys all know this bike very well. I'll listen and follow until I have something meaningful to contribute and then maybe I can help someone too. Until then I'm a student and even then I'll still be a student I think :) I really appreciate the help too.

Title: Re: "Shh" sound when decelerating
Post by justin_o_guy2 on 05/26/15 at 11:57:55

What part of Houston are you in?

Title: Re: "Shh" sound when decelerating
Post by chzeckmate on 05/26/15 at 12:10:39

I live in Westchase. I-10 @ beltway 8

Title: Re: "Shh" sound when decelerating
Post by jcstokes on 05/26/15 at 12:32:45

How are the brake pads?

Title: Re: "Shh" sound when decelerating
Post by justin_o_guy2 on 05/26/15 at 12:45:09

605F595E43446C2A0 wrote:

I live in Westchase. I-10 @ beltway 8

I went to Aldine jr high,Aldine Westfield, IIRC. LIVed across the street from Greens Bayou. Wonder if it's under water there..

Title: Re: "Shh" sound when decelerating
Post by chzeckmate on 05/26/15 at 16:20:58

2B2232352E2A2432410 wrote:

How are the brake pads?

They have about 5k on them according to the service records. The rear squeals a bit when they're cold but that's pretty typical in my experience with drums.

Greens Bayou is flooded as is a lot of Houston right now. My sister lives out that way. Small world.

Title: Re: "Shh" sound when decelerating
Post by jcstokes on 05/26/15 at 16:34:07

I'm not sure if the OEM ones are very long lasting, it might be worth looking.

Title: Re: "Shh" sound when decelerating
Post by justin_o_guy2 on 05/26/15 at 18:32:27

If you suspect the front brakes, gently pry the pads away from the disk and go ride, using only the rear.
If you get in a bind and Need that front brake, it may not be there for you on the first squeeze of the lever, so, plan where you do it.
If one side is wearing noticeably more than the other,then the caliper is not floating on the pins like it should.

Title: Re: "Shh" sound when decelerating
Post by chzeckmate on 06/03/15 at 00:25:45

Report: After a week of trying to reproduce the sound I haven't been able to. I did adjust the preload of the shock up two notches from the bottom for a firmer ride so I'm guessing that adjusting that did something to stop the sound. It feels a little too stiff now so I'm going to drop it back down one notch the next time I take it out. I'll report back again then.

Title: Re: "Shh" sound when decelerating
Post by justin_o_guy2 on 06/03/15 at 08:34:58

Thanks for the update.