Strange exhaust tones.... - Wrist Twisters
 
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post #1 of 17 Old 05-04-2012, 05:43 PM Thread Starter
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Strange exhaust tones....

So, to set up a little premise.

I was riding down to Deal's Gap last weekend and my 'negative' terminal lead sheared off causing my bike to lose all power after a violent bang. Long story short the we fixed and crimped a new terminal lead on the wire and I rode the rest of the day with no problems that day. We/I was riding hard, 100+mph for a while, at least for more extended periods of time than what I'd done before and on the dragon/cherahola was pushing the bike hard.

So, on the way home on Sunday, I started to notice a bit of a 'vibrato noise' coming from my exhaust. A pulsating tone instead of the steady exhaust drone of a bike cruising down the interstate. Bwaaaaaaaaaaaaaaaaaaaa vs Bwaaaawaaawaaaawaaawaaawaaawaaa. If that makes any sense.

Well, Tues and Wed this week, the sound was more noticeable and has me wondering what might be going on.

Here is the diagnosis:

- There is nearly no sign of it at all in 1st gear.
- In 2nd - 6th gear, showing up at ~4K RPM through 7K RPM, the vibrato noise is quite prevalent.
- Power delivery seems to be just as smooth as it ever was. Acceleration is smooth as well. There is no backfiring, pinging, surging, choking, sputtering, kicking, fucking, rocking, knocking, rattling, chattering, from the engine.
- Every bit of the annoyance seems to be coming from behind me.
- There seems not to be any power loss to the bike (if there is, it's awfully minute)
- The sound of the exhaust is it's normal pitch, but with the vibrato added in at the aforementioned RPMs.

Maint done

- Checked all basics: oil, tire pressure, batt leads, cracks/broken stuff on bike, leaks, etc...
- Removed air filter, inspected filter/air box, replaced filter.
- Re-mapped my PCIII fuel injection computer.
- Removed slip-on exhaust cans/inspected, nothing.

I've googled the problem, searched my maint manual, talked to a professional auto-mechanic of 15 yrs, all with no promise of what the hell is going on. So, I'm at a loss with what is going on with my bike.

All in all, it doesn't feel like there is anything wrong with the bike. But the exhaust tone sounds like a fucking annoying opera singer. It's annoying and prevalent enough to make me think there is something wrong with the bike, especially since I've never ever noticed it before in the 3+ years of owning it.

I don't want to take it to a dealer and try to see what's wrong with it, but between myself, other riders, and mechanics, no one seems to know what might be wrong. Anyone herehave a clue? I just find it strange that it came about after my neg terminal lead broke off and the bike shut down a bit violently. But after fixing it, seemingly I didn't notice anything wrong the whole rest of that day riding, and not until the next day.

Slow is smooth, smooth is fast.
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post #2 of 17 Old 05-04-2012, 06:53 PM
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Well it sounds like bracket or weld broke and is vibrating at certain engine frequency. It might be inside the exhaust or a mounting structure.
A first guess...
Mark

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post #3 of 17 Old 05-04-2012, 06:55 PM
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Perhaps an intermittent/loose crimp on the new ground lug?

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post #4 of 17 Old 05-04-2012, 07:02 PM
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Quote:
Originally Posted by Mark919 View Post
Well it sounds like bracket or weld broke and is vibrating at certain engine frequency. It might be inside the exhaust or a mounting structure.
A first guess...
Mark
Regarding this, check the exhaust bracket under the bike. These are known to break, could be it

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post #5 of 17 Old 05-04-2012, 10:56 PM
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Could be time to re-pack the Satos. Maybe a big chunk of it shifted?

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post #6 of 17 Old 05-05-2012, 06:18 AM Thread Starter
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Quote:
Originally Posted by undercover919 View Post
Regarding this, check the exhaust bracket under the bike. These are known to break, could be it
Will check that today.

Quote:
Originally Posted by g00gl3it View Post
Could be time to re-pack the Satos. Maybe a big chunk of it shifted?
That was my next line of thought and the advice of some others after doing what I've done so far.

I'll throw on my stock mufflers, and give the Satos some work.

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post #7 of 17 Old 05-05-2012, 02:24 PM Thread Starter
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So, here the latest. I took off my satos, inspected inside with no signs of cracks/damage, inspected down my Y pipe, went to put on my stock cans only to find that I no longer have the hardware to do so. Must have lost it somewheres....

Anyway, after that I did some basic maint with the bike on a stand; set correct chain tension, lubed, checked pads for grabbing, etc...

Took the bike out on the interstate and the same pulsing is going on 2nd- 5th gear 4k-7k rpm. This time, I thought to disengage the clutch while maintaining the same RPMs where it was pulsing. Shazaam. The pulsing stopped. So, this has me thinking maybe it's something in the drive system? Friction plates in my clutch? I have done 23k + moderately hard miles with the previous owner doing 16k miles on it with no clue how hard it was ridden. Might be a good time to just replace the clutch anyway...

Slow is smooth, smooth is fast.
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post #8 of 17 Old 05-05-2012, 05:01 PM
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did you bother to check your exhaust bracket like everyone advised to do so?

remember, KISS principle...

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post #9 of 17 Old 05-05-2012, 05:18 PM Thread Starter
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Quote:
Originally Posted by Pvster View Post
did you bother to check your exhaust bracket like everyone advised to do so?

remember, KISS principle...
Yes, checked out the whole exhaust system. Nothing visually wrong other than noticing my Y-pipe clamp was a little loose. But tightening that didn't fix the problem. It's not a bad idea for me to replace the clutch anyway, but I honestly don't think that will solve the problem. I'm considering replacing the ground cable and terminal with all OEM parts instead of the fix I got at an autoparts store.

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post #10 of 17 Old 05-06-2012, 09:31 AM
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hold on... you're making this waaaay too complicated!

did you check your airbox to make sure nothing was loose? check the headlight trim ring? check/re-torque the exhaust bolts on the headers? did you re-seal the slip-ons on the y-pipe correctly?

i'm very convinced its not drive-line related as you stated, but something vibrating at resonance from the driveline.

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post #11 of 17 Old 09-25-2012, 05:21 PM
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Pvster I'm new to this forum..happen to stumble across this one.. I've been having the same problem for the longest time now..not too sure what's goin..Recently did a complete tune up oil change,sparks, air filter...The power is there but it seems as if my exhaust is starving it doesn't scream like it use to almost as if it's being suffocated..this comes n go as I hit certain speeds...CCT, valve adjustment, exhaust servo.....

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post #12 of 17 Old 09-25-2012, 07:23 PM
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Kawaryder, welcome to the forum!

Sorry, I'm not familiar with the 636, or what you mean exactly. Hopefully someone can chime in to shine some light for you.

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post #13 of 17 Old 09-25-2012, 09:20 PM
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lol talking to the deaf guy bout exhaust sounds. lawls

in all seriousness, alot of the time its a placebo effect. Also different temps / bar pressures can change exhaust notes.

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post #14 of 17 Old 10-05-2012, 04:17 PM
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Have you looked at the flap inside the air inlet snorkle? Is it opening and closing while riding?

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post #15 of 17 Old 10-07-2012, 11:09 PM
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Quote:
Originally Posted by nalla View Post
Have you looked at the flap inside the air inlet snorkle? Is it opening and closing while riding?
have you seen yours open and close,,,,,im guessing no......the flapper dont work like that.....all these years and knowone has a vid of the flapper working

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post #16 of 17 Old 10-09-2012, 11:53 AM
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My comment was to check if the flap opens and closes with vacuum. I don't think it's a good idea to hang off the side of the bike checking the flap.

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post #17 of 17 Old 10-18-2012, 10:17 AM
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Quote:
Originally Posted by nalla View Post
My comment was to check if the flap opens and closes with vacuum. I don't think it's a good idea to hang off the side of the bike checking the flap.
It could be entertaining to watch though...

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