gs 650 engine knock

[captainnimmo2]

I've seen a few threads in here on engine knocking.
I've got an 83 gs 650 e that knocks at 3300- 7000 under very moderate to heavy accelleration. Almost more of a clatter, does not sound dull enough to be in the lower end. Reminds me of piston slap or wrist pin bearing noise. The niose disappears when the #3 plug wire is shorted. No evidence of metal in oil. That plug seems to be a bit blacker than the rest. Runs great. It's been making the same noise for the 800 or so miles I've put on it. I picked it up at a yard sale for $75. Thought I'd strip the carbs off it for a gs 550 for my wife but all it needed was a 3 dollar fuse block from autozone. I've got lots of experience with cast iron v twins but I'm not familier with the sounds aluminum in line fours make.
I don't have a lot of time or money to start diggining around blindly.
Any suggustions?

[snowbeard]

I have the 81 GS650G, and I get a lot of clatter as well. I won't tell you it's nothing, but I've put about 6K miles on it in the last three years and it's only getting marginally worse. it all comes and goes, randomly different... I haven't found anything that stops it tho, like your #3. for $75 you could get your money's worth easily before it blows up, but its always nicer to get even more!!!

someone else on here might have a better idea of the reason, and I'd be glad to hear it myself!!

good luck!!!

[IanFrancisco]

Might be due to the use of 87 octane gas. I was riding today, the temp. was around 90 degrees F, and I was riding moderately up the local canyon. If I rolled on the throttle in a higher gear at lower revs (3-4k) I heard a clatter. The oil temp gauge read around 250F. It was enough to make me stop, turn around and head back down the hill. Since I needed gas I filled up with premium, let the bike cool off for a few minutes and went back up the hill to if it made any difference. The oil temp was still high, but the clatter was gone. I was able to finish the 60 mile ride without any issues. Fun ride, but I don't really like seeing oil temps that high. Makes me wonder if I should look into an oil cooler for my scooter...

[captainnimmo2]

Did a comp test tonite, didn't before as my gauge was broken, all around 100/psi. Lowest one was #2 @ 95. Tried 93 octane, no luck.
all the plugs are running whitish beige now. Looked down the cyls with a probe light nothing drastic. Reset timing chian adj to make sure its seated.... If the noise is nothing more than an annoance I don't care, I just fon't want it to explode somewhere inconvenient. Did I mention it puffs blue smoke on cold start-up but doesn,t seem to use any oil.

[Chris Daniel]

I have had a knock in my 650 ever since I got it.

You cannot hear it at all when the tank is full, but when it gets more than half empty it starts getting louder and louder.

After many attempts at finding the problem I happen to stick my screwdriver (listening device) against the fuel petcock........BINGO that thing is clicking like crazy. When it is full of gas it is muffled, when it is empty the inside of the tank is like a megaphone.

Other than that my 650 makes a fair amount of different sounds when it is warmed up, timing chain, clutch basket, valves, etc etc etc. I have found that none of them, at least on my bike anyway, is detrimental to its health in any way. This winter I am going to put a new topend on it because I have a headgasket leaking a little oil...so its a reason.

You said it quits when you short the #3 plug wire......that usually indicates a rod bearing. When you short the plug wire it takes the load off the rod bearing and makes it quiet.

What weight oil are you using?

I am running 20w50 in mine and it seems to quiet it down a bit from 10w30/15w40, just makes it a little notchy shifting in the mornings.

Hope this helps a little bit.

[flyingace]

I have a similar noise in my 850. It isn't rythmic enough to be a knock - more of a clatter or rattle. It goes away when I pull #2 plug wire. I thought for a while it was #2 rod bearing, but the dowel test didn't indicate any movement of the piston. I've read in the old Q&As that improper machining makes the camshafts end chatter - but I don't think that's it. My current theory is something in or around the piston is making the noise. This knocking has been with me all 2200 miles I've had the bike.

Ace.