XJ750 4-2 Exhaust removal tips

Hello Everybody,

I am trying to isolate and identify a rattling that I hear. It intensifies at 3000-3500 and 5000-5300 RPM. The sound also changes depending on whether the bike is on the side stand or centre stand. When on the centre stand, the rattle is not as prominent, but on the side stand, the sound is a lot louder. And I cannot really reproduce the loud rattle at higher RMPs without actually riding the bike.

I have done some research and will be attempting to adjust the auto cam chain this weekend. If that doesn't resolve the issue, I've decided to check the exhaust gaskets/donuts.

I would like to know of any tips in disassembling the exhaust system.

Which bolts/screws should I remove first? Is it possible to check the header gaskets without fully removing the entire exhaust?

I have to service manuals (Hayes and another) and they are pretty good, but vague in this area.

Any suggestions and/or recommendations would be greatly appreciated.

I can also post a video or audio file of my bike running if that will help identify the rattling.

Also, a couple weeks back I took the maxim to my bike shop and my dude pretty much told me the sound is exhaust related and that he wouldn't recommend any service as it is not affecting performance. But the sound is annoying and I'd like my bike to be a little less noisy as I often ride at night and don't like annoying my neighbours.

Thank-you all for your time.

~metasoil

 

get out the penetrating oil, 8 nuts holding the headers to the head, 4 clamps holding the headers to the collector under the oil filter, 1 bolt in the center rear of the collector, clamps on mufflers at collector, bolts for mufflers
the 8 nuts and clamps , oil a few times, over a few days
if the header donuts were bad the pipes would move if you give them a firm shake
a cam chain cant make enough noise to bother the neighbors
the muffler / collector joint can be a real pain, oil it, tap it, pound it, pray, repeat
i'll take a guess at the rubber mount for the collector or a loose baffle in the muffler

 

thanks for the great advice. I'll start oiling the joints and nuts this week and hopefully have the exhaust off this weekend for closer examination.

how much would the pipes move if the header donuts were rough? would it be more than a slight wiggle?

also, when i tap my collector from the underside, i can hear a slight rattle. could that be the bad rubber mount?

 

i'am going to have to say they shouldn't move at all but the nuts might just be a little loose, but don't tighten them before you oil them, and don't break any, think two fingers on the wrench
any sign of carbon like a exhaust leak on the header clamps ?
i think you can get to this without dropping the collector, see if all the parts are there in the right order
if you do take the headers off, mark them, they look the same but their not

 

I recomend that before you tear the exhaust apart, get a piece of heater hose or 3/8 fuel line about 2' or so long.
Listen thru 1 end and use the other end like a stethescope to pinpoint the noise.

Good Luck

 

When the exhaust system is properly mounted and torqued it should NOT "wiggle." That being said, there are baffles in both the mufflers and the collector that can come loose inside. The rubber mount for the collector BOLTS onto it so it can come loose in a couple ways, or the rubber bushing could be gone. USE A TORQUE wrench, or as Polock says, think TWO FINGERS on the wrench when tightening the exhaust studs at the head. If you have a pipe or pipes loose at the head, I would replace the gaskets on those, and properly torque them. The proper torquing procedure is to have the entire system (all joints/connections) loose and then start at the head and work rearward torquing as you go.

 

thank-you all for your repllies.

Polock: in regards to the flange bolts and rubbers in the diagram you have attached - the bolt and rubber was missing a month ago or so - and I replaced them, so everything in the pic you posted is present and in good shape.

There are no signs of carbon/exhaust leak on the header clamps. And the header pipes don't move when jolted.

Hvnbnd: Good advice - I'm not really looking forward to disassembling the entire exhaust system. Any additional information you can give me on this stethoscope contraption you have described. Will that effectively allow me to isolate sound? I assume the sound will get louder when I get to the affected area?

bigtiz52: Any advice on how to check the baffles in the collector?

Is there a way to remove the collector alone? also it looks like I'll be removing the centre stand as well, does that sound right?

Please excuse some of the questions, if they seem basic. I'm still learning.

Thanks again for all of your advice.

 

Take a length of hose, even an old piece of gaden hose.
Put one end to one of your ears and just puff or speak softly into the open end.
As you will see any air leakage or noise that can be pinpointed to a specific area will come thu loud and clear.

That's the spot to fix. Make sure to make a note of each leaking spot.

Depending where the leak is, determines how much tearing apart you will need to do.

Remember to be safe doing this and be careful for things like exhaust or steam or very loud noise.

Good luck