Engine noise during acceleration??

[motopsycho87]

Hi all, wondering if you can help being the experts n all. 

Got a b12, 2002, 20,000 miles and I'm getting a a really annoying knocking / rattling noise on acceleration. Initially I thought it was detonation due to fitting the ignitech, but it still happens when using standard CDI.

Bike is pretty much standard except stage 3 dynojet, pods and exhaust.

The noise isn't there at start or idle, or revving freely. It comes in initially about 2000rpm, then goes, then comes back about 2500-3000rpm, then goes, then comes back between 4-6000rpm albeit quieter, at these revs it sounds more like a grumble than a knocky rattle.

It is apparent in all gears, comes and goes quiet to loud to quiet, extremely consistent with revs. It's not there when I pull the clutch in. It seems to get louder the further the throttle is opened, but disappears with clutch.

Its really doing my head in, and seemed to get louder when I changed the headers, but I've tightened and checked for leaks and nothing.

 

Please help!!

[Spazpecker]

Oil pressure related? Small ends? 

[Swiss Toni]

Try balancing your carbs. 

[Dezza]

Check the cycle parts. The last time I had anything like that happen was due to one of my tank rubbers becoming displaced.

[motopsycho87]

7 hours ago, Swiss Toni said:

Try balancing your carbs. 

Did them after valves, that was my first hope

 

It sounds like a leaky header, but only happens under load, and comes and goes at very specific frequencies???

[motopsycho87]

 

Doesn't happen in neutral, but happens in gear with brake on

[Gixer1460]

Maybe i'm deaf (dumb fool! You are! - in one ear LOL!) but just sounds like a Bindit cos I hear nothing odd!

[no class]

all I hear is the sound of the carbs with the sound resonating in the airbox . 

[no class]

did you drill any holes in the airbox cover ?

[Captain Chaos]

On 4/19/2021 at 10:43 PM, motopsycho87 said:

pods

induction noise?

[vizman]

It’s a mk11blandshit, the noise is just it quivering as it knows at some point someone is gunna put it in something decent and boost the shit out of it.

[vizman]

I can’t hear anything rattling....or at least nothing unusual. My speakers are probably full of tobacco like.

[wraith]

Sounds ok to me to, heard much worst than that.

If you don't like the noise, get some ear plugs 

[motopsycho87]

Another video, the last run at 4k rpm is the loudest

[motopsycho87]

I've also drained the oil, no sparkles, cut open the air filter, no flakes 

[bluedog59]

I can't hear anything but from your description I would have a check of the gearbox output shaft bearing and possibly the one behind the clutch. 

[motopsycho87]

2 hours ago, wraith said:

Sounds ok to me to, heard much worst than that.

If you don't like the noise, get some ear plugs 

Ear plugs make it louder!!!

[no class]

4 minutes ago, TonyGee said:

you say it goes away when you pull the clutch in when riding, but in the video you put it in gear and rev it, the rear wheel isn't turning so you must have the clutch in ?????

...,. he is sliding the clutch out while holding the brake .

[Spazpecker]

Sounds better than mine! 

[bluedog59]

54 minutes ago, TonyGee said:

the output shaft isn't turning when the noise happens. its just in gear with the clutch in. 

I was going off his description as I can't hear anything in the video. I would still give those bearing a check, it's a B12 so it's probably been wheelied a few times. I've had the one behind the clutch go before.

[bluedog59]

My clutch pushrod snapped. Noticed the clutch lever was having less and less effect on a long ride home then, nothing. The last 20 miles home was, erm, interesting.

[motopsycho87]

6 hours ago, TonyGee said:

im just wondering about the engine noise, was it already their when you got the bike ? ive heard of 1 or 2 bandits with an out of balance crankshaft.  

It seemed to be there but quietly. I put a Lextek exhaust on and suddenly it's really loud. 100% not leaking at headers or spring rattle though.

 

 

I've watched a few videos on YouTube of people riding the bikes and there's no similar noises. I'm wondering if it's just insane intake grumble?

[paddle]

Sounds 100% better than mine