Hi guys, new to the forum but I've heard a lot about this place!

I was hoping someone could shed some light into my very strange engine/clutch/gearbox knock... so I bought my GS500E last December to use as my winter hack - I enjoyed the bike so much through the winter that I decided to keep it along-side my ZXR400. Now, this issue has been happening ever since I got the bike, but upon tampering with the idle I realised it will only do it around 1800-2000 rpm, before or after that and the bike runs beautiful and smooooooth 

Anyway, I have uploaded three videos to YouTube - the first is with the idle set to around 2000 to produce this strange knock, the second is me adjusting the idle to make it both vanish, and then come back again - the third is me revving the motor through the rev range to show that after 2k rpm, the noise does in fact vanish.

Part 1
Part 2
Part 3


The things you'll hear:
* backfire through the carbs (not sure if this is to do with the mixture screws)
* cam chain whirling noise (don't let this confuse you with my problem)
* the self-destructing soundalike engine  - it's intermittent but at 2k RPM it will be there - before or after it dissappears/

If you could spare some time and watch the videos, that would be mega - although an indefinite answer will earn you a beer

Thanks for reading/watching/answering!
Shiny side up.

Turkish

i am having the same issue. Well sound wise at least. So I am looking forward to answers too

Does yours only bang around the 2k mark? Does it drop revs sometimes due to the banging, and once you get past 2k the banging stops and the engine runs as smooooooth as you like? WEIRD - I'm yet to find someone with the identical problem lol

What you are hearing there is the backfire through the carbies from the lean missfire. To a degree it is normal and mine has done it from day one (new). Yours is worse than mine and may be caused by tight inlet valves, unbalanced carbies or too low float levels. Mine improved dramatically by running larger than recommended valve clearances. I have NEVER touched the carbies except to adjust the idle speed.

Macka

Hi mate thanks for the response - ignoring the backfire, listen to the knock - definitely not valve related - sounds to be behind clutch, or around that cover 

Turk

Quote from: TurkishJordo on October 12, 2015, 02:53:46 AM
Hi mate thanks for the response - ignoring the backfire, listen to the knock - definitely not valve related - sounds to be behind clutch, or around that cover 

Turk

As I said, the noise IS the backfire or popping in the intake. It is inconsistant and is NOT a mechanical noise. I did not say that it was valve noise but that it CAN be caused by tight valves which make no noise themselves. It is the same as mine was from new but mostly disappeared after setting the valve clearances a little larger than spec. Now. at 7 years old, my engine no longer makes the noise but it has never had ANY repairs.
Perhaps if you take off the seat and listen at the inlet of the air filter you might hear the popping.   

The knock is definitely mechanical, it didn't use to backfire until I adjusted the mixture, this is a knock that happens way before the backfiring (when bike is hot)

Gsjack will add his experience but search for loose starter clutch on the forum.

Funilly enough I was thinking of that last night! It definitely sounds like a loose or knocking cog - did originally suspect gearbox or starter motor/clutch! I will do when I get home, thanks for that

Okay so today I stripped the clutch side cover off and found a cog under the clutch was in fact pretty wobbly, also the clutch centre nut has some play in it as if it's loose? Didn't capture a pic of the clutch nut but here is the loose cog - anyone know what it is?

Also is the clutch nut meant to move back and forth slightly?

(not letting me upload pic)
- cog is behind clutch and underneath

I would definitely like to see a pic of that if you figure that out. I'm glad to hear there's some hope for this problem!

The site storage capacity is very limited, best to include a link to Photobucket or similar

Sent from my SGH-I337M using Tapatalk

I tried too and couldnt get it but I just used tinypic and used the forum code and that works great!

http://postimg.org/image/5putzlj8t/
Might need to turn your monitors for this one lol, see the cog stashed behind the clutch

That gear drives your oil pump, it does have a little bit of free play.
I don't have the manyal with me but that clutch not should be torqued down fairly tight so it should not be loose as you have found. The starter clutch itself does move unless the dogs are in place while starting.

Sent from my SGH-I337M using Tapatalk

Yeah the clutch nut is loose, oil pump driver cog has movement in all directions, the cog behind the clutch can be moved with a but of force - no other cogs in there move out of place - it seems like the oil cog driver is making the noise, as it echos in there - I doubt the clutch nut being loose is making that knocking noise, driving me mad lol

Is the side cover gasket reusable?

I find generally it's better to use a new gasket