Thumping in neutral. Need advice

[03TBUSA]

2003 With 22k. All stock
First noticed the thumping a couple of weeks ago after starting her up after the freezing months. I changed the oil before putting her up. Didn't notice anything after riding a couple of times then.

Its more noticeable in cold start. One thing is it only does it in neutral and when the clutch is not engaged.
Some posts say its "normal", but I don't think so when the engine sounds like its going to throw a rod or something.
Anyone out there had this problem and what can I do or repair or replace to fix it. My oil level is half way between low and high thru watch glass.
She rides like a dream otherwise and no weird noises while buzzing around town.
Any advice will be greatly appreciated.

 

[jellyrug]

Normal.

 

[IG.]

It would be helpful if you recorded the sound and let us listen. The engine does sound differently between hot and cold, but shouldn't be so bad that you get concerned. I also noticed that when cold and at a certain low RPM, timing chain can slap around with a little more noise.

So, if you just started cold bike, you hear that sound, right? But if you switch into gear, you don't. Is this the case?

Any chance you idle RPM is a bit on a low side. What is it?

 

[pack mule]

I have an 03 also and mine has always done that. It bothered me at first but when everyone said it was normal I stopped worrying about it. I've got 55k on it too.

 

[03TBUSA]

Ok. So today I started her up, but held the clutch in for about 10 seconds before releasing to neutral. No thumping or knocking noise whatsoever. So now I'm really scratching my head.

 

[RedBusarider]

You said it rides like a dream, so what's the problem?

I'll bet as it warms up more (can't ride here yet because it's still to cold) the problem will go away if there was a problem to start with.

I don't like cold, so I assume my Busa wouldn't like it either.

 

[IG.]

Ok. So today I started her up, but held the clutch in for about 10 seconds before releasing to neutral. No thumping or knocking noise whatsoever. So now I'm really scratching my head.

When did you change oil last time, and what oil/grade did you put in? It's a long shot, but the reason I am asking is that when cold, oil seems to stick clutch plates together. If there is any kind of irregularity between the plates, I imagine the following may happen - as the plates move past each other, they pass low and high friction areas with every revolution, hence thumping sound. Because there is no load, this may be inconsistent - at certain moment one set of plates drags another set of plates. When you pull the clutch in, you increase the distance between the plates, so they pass each other without much rubbing against each other. I figure that if you had an old oil inside or a thick oil like 15W50, this could play a role.

Another test would be this... when the bike is completely cold, like sitting overnight, put it in 1st gear, pull the clutch and see if you can easily move the bike. Initial resistance is normal, but then it should move relatively easy. See if by any chance when you move the bike whether you experience a few ft easy, and a few ft hard alternating. If so, that would support my guess. Then, the question would be what kind of irregularity you got there?

All of the above are my guesses of course, so don't take it too seriously.

 

[proud dad]

I remember that noise on my old gen1...sinc the throttle body's and it goes away..crank gear and the gear on the clutch basket are bouncing against one another due to engine not as smooth as it should be..pull in the clutch and the weight of the trans is lifted off the crank..And no you won't feel it running down the road.

 

[03TBUSA]

IG. I did an oil change right before the winter. Used the recommended 10w40. I'll have to try that test you mentioned. I think I need to sinc the throttle bodies. Where can I get the tool for that?

 

[IG.]

IG. I did an oil change right before the winter. Used the recommended 10w40. I'll have to try that test you mentioned. I think I need to sinc the throttle bodies. Where can I get the tool for that?

You need vacuum sync gauges, but honestly don't think this is it. The worst that can happen with throttle bodies being out of sync would be that your idle is not steady. I think you have something else.

As I said, recording of the sound could be helpful because you could be talking about one thing and we could be talking about something else.

What's your idle RPM when the bike is cold?

 

[VIPER]

i am local to you in council bluffs....if you like we can hook up and i can let ya know what i think.

 

[FlatlandBusa]

You need vacuum sync gauges, but honestly don't think this is it. The worst that can happen with throttle bodies being out of sync would be that your idle is not steady. I think you have something else.

As I said, recording of the sound could be helpful because you could be talking about one thing and we could be talking about something else.

What's your idle RPM when the bike is cold?

Throttle bodies out of sync cause an uneven idle and can cause the clutch to make odd noises.

 

[IG.]

Throttle bodies out of sync cause an uneven idle and can cause the clutch to make odd noises.

Didn't know that. More reason to know whether his bike has "hunting" idle, and what's his idle while cold anyway?

 

[jellyrug]

Ok. So today I started her up, but held the clutch in for about 10 seconds before releasing to neutral. No thumping or knocking noise whatsoever. So now I'm really scratching my head.

So far, I have not seen a stock Busa, Gen I or Gen II that idles evenly after a complete cold start, for a few seconds until the ECU has time to back off the cold start fuel settings. And while that happens I have not seen a Busa that does not give the clunking noise with the clutch out in neutral, until it warms up after a few seconds.

Anyone have a different experience?

 

[proud dad]

So far, I have not seen a stock Busa, Gen I or Gen II that idles evenly after a complete cold start, for a few seconds until the ECU has time to back off the cold start fuel settings. And while that happens I have not seen a Busa that does not give the clunking noise with the clutch out in neutral, until it warms up after a few seconds.

Anyone have a different experience?

yes..

 

[03TBUSA]

Well haven't had a chance to start her up lately. Been busy trying to paint my fairings witch didn't go so well. Will def start her up today to try to figure this thumping noise. Thanks for all the replies guys