knocking at idle

When my bike is in neutral, and idling, it knocks. I think it's coming from the transmission area, because when I pull the clutch lever, the knocking lessens. And when I stick it in gear, the sound changes. At higher rpms I don't notice it.

This bike was essentially given to me a few years back, and I never had the time to get it running. It is only recently that it has been running, and so I don't know how it ran before. However, this knocking has been going on since it has been running normally.

When I began getting the bike going I found that the starter gear was missing. THe PO had lent the bike to a friend for a while before I got it. He phoned his buddy, and asked him whether he had removed the starter gear. His buddy said he didn't. THe bike used to start with the starter, so I thought that the snap ring might have come off, and the gear fell inside the crank case.....So, I ended up tearing it apart. I'm saying this because there is the potential that I didn't assemble it correctly, though I was pretty careful.

The knocking isn't that bad, but if it tells of a serious problem, then I'd like to take care of it.

So, anyone have some ideas, or had a noise that fits this description?

Any suggestions are much appreciated.

 

Most likely clutch plate rattle. My GS1100 has it in spades.

 

My '83 550 has the same noise. A light rattle that is audible on the left side of the bike in neutral, and it goes away when I pull the clutch lever or put it in gear.

 

Have the same thing on '85 700........

 

The thing to do, really ... is simply "Probe" the engine and listen to what's going-on inside.

I use a fiberglass rod made from one of those long orange-colored driveway markers we need when it snows.

Touch the engine ... anywhere you need to listen ... with one end ... and, "Listen" to the other end.
If you put hold it with your thumb applying pressure on the end of the rod ... you just can just put your ear to your thumb and get a real good idea of whats going on inside a running engine.

Obviously, rotational noise is going to be normal.
Occasionally, you'll detect other noises and be able to act before a problem arises.

This is an excellent way to determine if you have a real knock or an exhaust leak ... because the exhaust leak noise gets separated from the real engine rotational noise and you "Hear" the engine with no mechanical knock.

Tape a strip of paper to the end and you can probe for exhaust leaks without burning your hands. Just watch the paper flutter when it finds the leak.

Wrap some duct tape on the end -- "sticky side out" and use it to retrieve that dropped nut or washer you can see but can't reach!

 

so if it is the clutch plate rattle wat will fix it? no one is really giving any info on how to fix the problem

 

If it IS clutch rattle, it's not something to be fixed, it's just a characteristic of the bike. If it is really loud, it might be trouble in the bottom end, which would certainly require prompt attention. We're all just guessing here without hearing it ourselves. Usually, if it goes away with pulling in the clutch, it is clutch plates rattling around a bit when engaged.

 

If the Clutch Plates are rattling on an XJ-Bike ... I'd suspect somebody put-in the wrong Clutches.

The Drivers and Frictions get packed-in pretty tightly on the 650's, 750's and 900's.

You do understand how difficult it is to have a say about what might be making an unusual noise without the luxury of actually listening to the noise.

We wind-up telling you to 'round-up the ususual suspects!
Valve train noise. (Adjust the shims)
Cam Chain noise. (Manual jerk the slack out)
Exhaust leaks disquised to sound like everything from a bad Main Bearing, Spun Connecting Rod Bearing, Piston Slap ... and everything else other than what it really is.

What did you hear ... when you probed the engine???

 

Thanks guys. Haven't yet had a chance to probe, and won't untill tomorrow, But I'll get on that.

Me thinks it might be cam chain. 60 000 km.

Had a few filings on the oil plug magnet.

Brief summary of bike.

Got it...sat for couple of years.
Drained oil last year, did some work, and filled.

Got it running, rode it a bit. 500km max.

Drain oil, and found a few filings. Wondering if those filings were in there all along, or the found their way down to the magnet.

Just a small amount of filings, but they got me worrying.

 

I'm kicking aroud the idea of mounting a piezo mic to various parts of the motor and recording the noises. Then I can post them online for your listening pleasure.

 

Those 550's aren't fitted with an Automatic Chain Tensioner; are they?

So, you have to unlock it and manually take-up the slack.

A noisy Cam Chain will make a 550 sound like somebody playing a Polka on a washboard with a putty knife.

You really don't know what the noise is ... you just want it to stop!

 

My '82 550 has a manual chain tensioner. I have the clutch rattle also. Sounds like some marbles in a cofee can, gets a little louder as the engine warms up and goes away when the clutch is pulled. It doesn't make noise in gear going down the road, only in neutral with the clutch disengaged. I'm not to worried about it.

 

Find a mate with a Ducati, Any rattles you hear after that thing running will pale into insignificance. :wink:

Seriously, the XJ is renowned for owning a few rattles, the important bit is determining which ones are not meant to be there.

Known noises are:

Cam chain. Usually an irregular rattle or whirring. Fixable.
Primary chain. these can stretch over time but will never break. Usually only heard at idle. Ignore
Clutch. Not the plates, but usually the clutch basket. Runs on a brass? bush and often rattles at idle. Pulling the clutch will reduce the rattle.
Exhaust Some were double skinned and if the inner has rotted and come loose it will drive ya crazy. Also loose headers and loose baffles in the muffler.
Valves Rattle will change with revs. Fixable

ANd my favourite one that happened to me.

Fuel sender unit bent and the float rattling against the side of the tank from quarter full. :lol:

Hardest part is finding the specific noise as each noise seems to reverberate through the whole bike making it sound like it's somewhere it's not.

Stethoscope it. Screwdriver handle on the ear normally works for me.

 

The clutch on my 550 rattles at idle in neutral. It goes away as soon as I put it in gear.

A mechanic with a lot more knowledge of the XJ 550's than most said it's no big deal. Just something some 550's do.

He recommended that if it really bothers me (which it doesn't) to just get a louder exhaust. :wink:

 

Hey Jim-
I just figured out what my rattle was, anybody recommend a good 4-1 exhaust system for a 82 550??

 

The only 4-1 that I know currently available for the 550 is the MAC.