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Knocking sound from my 650gx

  • Thread starter Thread starter JCSkokos
  • Start date Start date
J

JCSkokos

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I know there are a few topics about knocking noises, and I have looked through them lightly but nothing stood out too great.
My gs seems to have adopted a knocking type noise, similar to the sound that a 4 cylinder Toyota has with rod knock. It doesnt sound at idle(the tapping noise I asked about a few months ago is still there) but under load around 3-5k rpms it knocks pretty loud. It doesnt do it if I am in neutral or with the clutch pulled and rev it up like the Toyota does though.

In my search I saw that some GS's have a roller-bearing set up that makes rod knock theoretically impossible.
I talked to my friend, [diesel]master tech, the other day and had him look at it and he said it sounds like a loud electrical popping and suggested the ignitor was arcing. I was under the impression that it doesnt work like that.
I recently had my headers off to replace those gaskets and saw that cyl1 was running very lean and 2+3 were rich and 4 was somewhere in between.
EDIT::Almost forgot, I changed the 15 year old stale oil out about 700 miles ago with a brand new EMGO filter. I used the Rotella Synthetic T6--5W-40::

once again, the bike is a 1981 GS650GX. Which of these would be most likely, or is there an even more likely culprit? I dont really wasnt to start taking things apart right now chasing a ghost.
 
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650G doesn't use a roller crank. And it's not the ignitor. My guess is clutch noise or a rod knock.
 
I hope its clutch noise. I was planning on doing some clutch work soon anyway, but the idea that the motor could be shot made me shy away a little.
 
Nessism said:
650G doesn't use a roller crank. And it's not the ignitor. My guess is clutch noise or a rod knock.
Click to expand...
Yes, it has plain bearing crank and needs lots of oil to keep things happy. If it "adopted" this knocking when you changed to the 5w-40 (?) oil, I'd change oil back to 15-40 and hope that that cures it.
 
I just had a 650g that I had to change the motor in because of a rod knock caused by a tip over and the bike ran on it's side for a spell and apparently got no oil to the bearings. Hopefully that is not the case with your bike
 
hjfisk said:
I just had a 650g that I had to change the motor in because of a rod knock caused by a tip over and the bike ran on it's side for a spell and apparently got no oil to the bearings. Hopefully that is not the case with your bike
Click to expand...

Mine fell over, but I am 95% sure it stalled before hitting the ground... It hapened so fast I cant be 100%

I will try thicker oil when I do the clutch work. I think I actually have a few quarts of Lucas oil from before I heard about rotella
 
Oil is not the answer. T6 Rotella is great stuff.

Do your clutch work and then go from there.
 
ok, I was originally going to do the springs & rough up the friction disks a bit. what else should I look for While in there?
 
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