engine knocking

[Peteortiz11]

hey! so I noticed when I start my gs850gl, there's some initial knocking on the left side of the motor (left side if I'm standing behind the bike). th knocking slows and eventually stops after a few mins. Ive checked my oil level and im good there. any thoughts? thx

 

[tom203]

Are you using correct oil for the secondary drive?

 

[Peteortiz11]

yes. Hypoid gear oil fully synthetic 75w-90

 

[tom203]

So it does this knocking in neutral after cold start? Or once you get in gear?
Does it seem that starter motor is working ok...no odd noises during cranking?

 

[Steve]

What is the frequency? What I mean is, does it seem to happen at engine speed, half engine speed, a few times per second, once every three seconds?

Can you start the bike and get closer to see exactly where it is knocking?

It is not uncommon to have "cam walk" on some bikes. The thrust faces in the cams wear away a little bit, allowing some sideways movement of the cam. In our bikes, that usually happens when the engine is warmer (oil thins out?). It will knock a few times, go a way, knock a few times, go away, etc. If the engine speed is raised above 1500 or so, it goes away because the cam chain is pulling the cam harder, not allowing it to slide to the sides. Your knocking right at start-up does not seem to follow this pattern.

By the way, the left side of the bike is still the left side of the bike, even if you are standing in front of it. :-k
All references to left, right, up, down are made as if you are sitting on the bike, ready to ride. If you were to stand at the front, with the wheel between your legs, headlight in your belt buckle and grab the handlebars, the throttle would be in your left hand, the clutch would be in your right hand, but the clutch is still on the left side of the bike and the throttle is still on the right side.

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[Peteortiz11]

Thanks for the (left/right) explanation. So the knocking only occurs when the bike is started; on the left side of he engine, and only for a few short mins. once the bike is warmed up it stops. starter is fine; appears to come from somewhere as high as the plugs

 

[Dogma]

"Somewhere as high as the plugs" could be cam end walk, but it seems odd that it would go away as the bike warms up.

I have a loose baffle in my RH muffler. It only rattles once the engine has warmed up. In fact, I've lately been taking that as my cue to shove the choke in, because it's ready. It stops again after the engine is hot.

Hang on, you say the knocking slows as the engine warms up? Slows, instead of simply getting quieter?

 

[leftlostcommonsense]

I had the same problem when using rotella T4 recently. I figured it was cam walk so never really payed any attention to it until I used a different oil and noticed it no longer knocked when I started it. My knock was on the other side right around #3 exhaust valve. The only thing I can think is maybe the top end was dry on startup causing the cam lobes to knock when hitting the shims idk but a different oil stopped it.

 

[Steve]

I had the same problem when using rotella T4 recently. I figured it was cam walk so never really payed any attention to it until I used a different oil and noticed it no longer knocked when I started it. My knock was on the other side right around #3 exhaust valve. The only thing I can think is maybe the top end was dry on startup causing the cam lobes to knock when hitting the shims idk but a different oil stopped it.

If your top end was dry, you really do need to ride your bike more than once every decade. :-k

Every bike I have seen the inside of, has had pools of oil around the buckets and shims. Even if the pool did not completely cover the shim, there was still a film of oil on it.

And, ... if your cams are "hitting" your shims, your clearances are WAY too large. Specified clearance is 0.03 to 0.08 mm. Considering that the maximum clearance of 0.08 mm is about the thickness of a piece of paper and that the ramp of the cam is rather gradual at that point, there should not be any "hitting".

.

 

[leftlostcommonsense]

If your top end was dry, you really do need to ride your bike more than once every decade. :-k

Every bike I have seen the inside of, has had pools of oil around the buckets and shims. Even if the pool did not completely cover the shim, there was still a film of oil on it.

And, ... if your cams are "hitting" your shims, your clearances are WAY too large. Specified clearance is 0.03 to 0.08 mm. Considering that the maximum clearance of 0.08 mm is about the thickness of a piece of paper and that the ramp of the cam is rather gradual at that point, there should not be any "hitting".

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I get what you're saying..I suppose it wasn't dry because I ride it often and there's always a pool when I open the top end too and my valves are within spec so I guess that only leaves Rotella t4 to be the culprit lol. Either way a different oil stopped it. I don't think rotella t4 is all it used to be because I had nothing but problems with it. I know many swear by it but my bike rattled like a tractor using it. Me being newish to bikes I didn't know any better until I tried a different oil lol.

 

[Steve]

I haven't used T4, so have no experience with it, but like you said, many others here DO use it.

I use T6 in all my bikes and have had no oil-related (or caused) problems.

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[leftlostcommonsense]

I can't find the t6 where I'm at for some reason everyone only carries the t4 so that's what I used the first couple oil changes and my bike had all kinds of top end noise the previous owner said wasn't there when he rode it years ago. Supposedly Suzuki oil is the only thing that had ever been in my bike before I got it and put in the t4 so that's what prompted me to change oils and all of the little knocks, chain noise and rattle is pretty much non existent compared to what it was with t4. I won't be using anymore t4 that's for sure. Anyhow hopefully OP's problem is something as simple as an oil change or chain tensioner reset and not something that'll mean removing top end.

 

[alke46]

I can't find the t6 where I'm at for some reason everyone only carries the t4 so that's what I used the first couple oil changes and my bike had all kinds of top end noise the previous owner said wasn't there when he rode it years ago. Supposedly Suzuki oil is the only thing that had ever been in my bike before I got it and put in the t4 so that's what prompted me to change oils and all of the little knocks, chain noise and rattle is pretty much non existent compared to what it was with t4. I won't be using anymore t4 that's for sure. Anyhow hopefully OP's problem is something as simple as an oil change or chain tensioner reset and not something that'll mean removing top end.

Have you tried finding the t6 in a farm supply store like tractor supply? Not sure what brand farm supply you have near you, but TSC is where I buy my t4 and they also have the t6 sitting right next to it.

 

[uk gs nut]

Could it not be a bit piston slap, piston clearance a bit on the large side. When it warms up piston expands a little and noise goes away