Moto seems too LOUD when the vboost kicks in. Help !

[Ryanneal]

2001 vmax

I'm hearing a very loud engine/exhaust sound as i rev through the gears, especially in 1,2,3 ears. It occurs as I'm revving hard, then when the rpms hit a point when vboost kick in, it sounds like I lose the baffle in the muffler, and the moto sounds too loud. I do know what the power surge should feel and sound like when vboost normally kicks in..... But lately, the noise hs been getting louder and louder. Makes me think that there is a baffle loose in the vboost system - just guessing.

The moto dyno's perfect. There are no firing or tranny problems.

It just sounds so obnoxiously loud that something must be wrong.

Dealership clueless.

Please help.

 

[old timer]

No such thing as too loud...that's the sound of freedom...AND , it's not illegal until you get caught...unk:

Shit , now I really do sound like a Harley guy...:confused2:

:biglaugh:

 

[ninjaneer]

if you can post a vid, i'm sure the guys would be able to provide more insight. i don't think i'm wrong or simply don't understand what you mean, but i really don't think there's a "baffle" in the vboost. the vboost system is simply a butterfly that opens up exposing the cylinders to 2x A/F mix.

what kind of exhaust do you have? it simply could just be the exhaust's baffle or packing.

No such thing as too loud...that's the sound of freedom...

+1 :biglaugh:unk:

Shit , now I really do sound like a Harley guy.

:rofl_200:

 

[Ryanneal]

The bike is completely stock. Original pipes

There is a distinct CHANGE in the sound during the power and range in each gear.
It sounds like the bike doesn't have an exhaust pipe, during that range in each gear.

If vboost opens an exhaust path, that is otherwise closed, I'm wondering if there is a loose part or leak /crack I'm that new exhaust path. I'm not too familiar with the system.

Thx a ton. Pls help.

 

[ninjaneer]

If vboost opens an exhaust path, that is otherwise closed, I'm wondering if there is a loose part or leak /crack I'm that new exhaust path. I'm not too familiar with the system.

ya, the vboost's butterflies are in the intake manifold.

 

[Ryanneal]

I guess I believe I am hearing MORE EXHAUST noise.
And guessing that it might be escaping/leaking if a new exhaust path is opened up. For example, if exhaust normally doesn't travel through a certain tube, now it does because the butterfly valve opens, then maybe the new tube/path is loose or cracked, and I hear engine noise. If the part were snug, it would "baffle" the sound.

Speculating.

I have 24k miles. Original pipes.
I am not sure, but if the pipes were bad, seems they would be noisy at all rpms in each gear.


Thx!!!

 

[ninjaneer]

I am not sure, but if the pipes were bad, seems they would be noisy at all rpms in each gear.

agreed. hmmmm. you think you could post a vid?

 

[ninjaneer]

have 24k miles. Original pipes.

are you the original owner? if not, perhaps the PO modded the exhaust cans by punching a hole in the baffle wall?

 

[Ryanneal]

Well, I'm not sure what to video. The condition occurs only when riding the bike, and I can't film and ride. I have only mastered drinking, smoking, and riding. Kidding.

Anyway, if first thought the noise might be tranny, but when it dyno'd smooth, the dealer ruled that out.

I suppose I can visually look for any black exhaust smoke staining around the manifold. But hell, I'm not sure how to get at that part ???

 

[Ryanneal]

I am not the original owner. However, I have owned it for 10,000 miles and I have noticed the problem begin and get worse. It was not this way when I bought the bike. Also, any pipe mod would be heard at all rpms, not just the power band, I would guess

 

[ninjaneer]

so, is it a clanky sound? or a grinding sound? maybe a cracking or a metallic raspy sound? sorry, other than a packing-less can, i'd like to know more about what it sounds like you mean by "losing baffle". please don't be offended by my layman questions, but perhaps your responses will excite one of the veterans to determine a solution.

 

[naughtyG]

This sure does sound strange - the vboost opens valve in the intake allowing more fuel/air into the cylinders, but has nothing to do with the exhaust.

I'm wondering if there might be something silly like a vacuum plug missing, or a bad/split/cracked rubber boot around or under the vboost valves?

Can you confirm the exact rev range indicated on the tacho within which this noise is heard?

Also maybe if you had a friend on a bike you could video what happens - it's really hard without hearing it. BTW - does it not do it when you rev the bike in neutral?

 

[jfeagins]

...And I'm sure you're not just hearing the back tire turning loose when the v-boost kicks in...
First time I've ever heard of this. W/o hearing it on audio or vid, my guess would have to be a down pipe with a cracked inner liner. It may only be sounding off under the added exhaust pressure in those upper RPM ranges.

There's also a possiblity that one of the rear down pipe heat deflecters have come loose, or cracked from their mounting holes. My 85 did this, but as I recall, that part would vibrate/rattle at idle as well.

 

[hijacker]

THere is no change in the exhaust when the VBoost is engaged. The only change is in the intake; air/fuel mixture. No exhaust.

 

[dmax1]

Fuel, Timing , Possible Spark knock. :ummm: Vid would help.

 

[Fire-medic]

OK, my input is that one or more of the muffler/exhaust graphite 'tubes' has failed and is allowing the noisome exhayst when the VBoost engages. That, or an actual exhaust hole exists, except that you would expect that to evidence w/an always-noise-laden exhaust.

 

[Blurr]

Don't really need to see anything just hear it, if you can, toss a go pro in your backpack and go for a ride.

 

[Fire-medic]

Or get a smartphone bracket for the handlebars. Try a GIVI.

 

[bazwell]

Did it make the sound on the dyno? Coz that would be the time to ID exactly where the noise is coming from.
Also, have you checked the airbox and intake boots aren't loose or broken anywhere?

Really, we need a sound clip!

 

[Mr. Max]

Leaking exhaust or downtubes? Are downtubes tight? If it leaks somewhere, I think more revs = more noise maybe? Just rev it while parked and kinda feel around with your hand, you should be able to feel gases coming out of leaking point, if there is any.