V7 lll Stone 750 2021 - Knocking sound while riding from left upper cylinder.

[Beavis]

Hey guys, my V7 lll Stone (750) makes a knocking sound from left cylinder when I push the throttle , the valves are adjusted and only have 3800km ( Bought it second hand with 3400km) .

After check , I have noticed the rocker guides , and the exhaust is tight , the intake is loose. Also checked the right cylinder and both guides are loose.

I have uploaded a small video showing what I have found :

https://youtu.be/1nAQRI7w14I

Can someone tell what's wrong here? Too tight or too loose ? What is correct ?

Thx in advance..

[guzzisteve]

It could be valves, guides, rings and any other parts sourced from China, some go bad but most are ok. If the valve gets tighter it could be hammering in a pocket in the seat.

If you put cylinder on TDC compression stroke(were you check valves) both rocker pins should have some play because you have play between rocker & valve. Pins could have play as in your video(normal).

There is a forked plate on L & R rocker tower that holds the pin in place w/screw. On the top side is a spring washer like they always use to take up play on end of rocker. If those plates are in place tight and not worn all should be good.

[Beavis]

It could be valves, guides, rings and any other parts sourced from China, some go bad but most are ok. If the valve gets tighter it could be hammering in a pocket in the seat.

If you put cylinder on TDC compression stroke(were you check valves) both rocker pins should have some play because you have play between rocker & valve. Pins could have play as in your video(normal).

So the rocker pin should have some play on TDC , but the intake have some play , and the Exhaust don't . Should I consider that exhaust rocker pin isn't good? I know that pins have some spring washer in the end , can that cause this noise? Because the noise I hear is like the one I hear when moving the pin with finger tips.

[guzzisteve]

That all is normal operating, should move. Check valve clearance. Is it normal?

https://guzzitek.org/atelier/pb/750/Moteur-Boite750IE_Atelier_Compil.pdf

Here's a book on engine

The rocker pins are made to float back & forth. One that doesn't move may have pressure on it.

Are you sure the noise isn't detonation of spark? Makes a rattle sound.

[Beavis]

That all is normal operating, should move. Check valve clearance. Is it normal?

https://guzzitek.org/atelier/pb/750/Moteur-Boite750IE_Atelier_Compil.pdf

Here's a book on engine

The rocker pins are made to float back & forth. One that doesn't move may have pressure on it.

Are you sure the noise isn't detonation of spark? Makes a rattle sound.

I have edit my previous posts , because i was wrongly calling the rocker pin as guides. Maybe now makes more sense.

Another question , does the rocker pins have some correct way to be installed? or just put inside and screw the locking fork plate?

[guzzisteve]

I  would pull off the other head cover and look to see if washers are on the quiet side.
The pin should go in far enough to put the cap fork in the groove on one end. Screw to lock in place.
I wonder if the rockers were moving back & forth on the pin making noise. This is why I asked to see if that spring washer was on the quiet side.
Yes, I know what the book shows. Side spring washers. None of that stuff should be going sideways to make that noise.

[Beavis]

I  would pull off the other head cover and look to see if washers are on the quiet side.
The pin should go in far enough to put the cap fork in the groove on one end. Screw to lock in place.
I wonder if the rockers were moving back & forth on the pin making noise. This is why I asked to see if that spring washer was on the quiet side.
Yes, I know what the book shows. Side spring washers. None of that stuff should be going sideways to make that noise.

Noted. But does the rocker pin have a particulary position to be installed or doesn't matter ? Because it does have some cuted/straight surface on it.

[guzzisteve]

I don't think so, they can rotate. The flat spot w/hole is to let the oil under pressure go the distance of pin. Oil comes out both sides of the rocker bushing when running. Lots of oil up there while running.
I'll be back tonight, gotta work today.

[Alfetta]

Beavis, you state knocking sound when i push the throttle....
I am wondering when and how you "push" the throttle, meaning do you hear this sound if your at 2K rpm and you push the throttle and hear the noise, and is the same noise happen if you are at 4K and push the throttle ??

[Beavis]

Beavis, you state knocking sound when i push the throttle....
I am wondering when and how you "push" the throttle, meaning do you hear this sound if your at 2K rpm and you push the throttle and hear the noise, and is the same noise happen if you are at 4K and push the throttle ??

Yes it happens after a normal throttle push I would say between 2k and 5k , after that I can't noticed because it's too much noise :). Also only after engine heat up. If I stay the throttle still , the sound disappears.

[Vagrant]

I suspect you are lugging it. Never let it drop lower than 3500 RPM. If that doesn't cure it get an "Upmap" for it.

[Beavis]

I suspect you are lugging it. Never let it drop lower than 3500 RPM. If that doesn't cure it get an "Upmap" for it.

I have two Guzzis. My 2019 dont do this.

[Beavis]

Well...hope this was the cause...

[Cal3]

uh....oh......hopef ully the rest can be unscrewed.....and not much debris inside the cylinder. I guess that is an age old lesson, always check the simplest things first?? :-0 I wonder if that is a a fake NGK or a real one?

[Beavis]

uh....oh......hopefully the rest can be unscrewed.....and not much debris inside the cylinder. I guess that is an age old lesson, always check the simplest things first?? :-0 I wonder if that is a a fake NGK or a real one?

Fortunately I have the right tools , and was a clean cut . No debris , also the extractor once it grabbed was a clean and easy extraction. Too bad I can't buy spark plugs today here in my country . I really think this is a fake , don't show any comparison with the one I have from another bike.

[Vagrant]

Yeah, that'll do it.
Fake NGK???

[Beavis]

Yeah, that'll do it.
Fake NGK???

Unfortunately yes , surprise or not , it was put in there by the dealer.

[Frenchfrog]

Nice save Bevis...I bet your relieved and now you are 90 % certain of what the noise was.

[Beavis]

Nice save Bevis...I bet your relieved and now you are 90 % certain of what the noise was.

Thx bro. I was indeed. 😅. Hope this was the problem. Let you know Thursday.

[Dirk_S]

One thing I’m curious about. I didn’t think they released a V7 III in 2021. I thought they were all E5 850s by then.

[Beavis]

One thing I’m curious about. I didn’t think they released a V7 III in 2021. I thought they were all E5 850s by then.

Mine was the last of his kind. JANUARY 2021

[guzzisteve]

Well...hope this was the cause...

Hey, that'll do it !!! WTF  Over    Ha Ha Ha Ha         I would still pull off other cover & look at where spring washer should be.

[Beavis]

Hey, that'll do it !!! WTF  Over    Ha Ha Ha Ha         I would still pull off other cover & look at where spring washer should be.

No need , already know it. The spring washer stay between the rocker arm part and his support. Outside.

[Beavis]

Well the problem was found .

It wasn't from the cylinder but near.

After taking every cover , anything than can be removed and make noises ...

It was a bad hose and cable management from factory . Those hoses than goes to the EVAP Canister were a mess , and the valve that is at the middle of one of those hoses , was very close do the base of the footrest , hitting when riding between 2000/4000rpm.

Put a rag between first time , problem solved. Rearranged the hoses and cables , the valve stays now on a lower position , were it should be at the beginning. No more knocking sound.

[Moparnut72]

If I had to guess I think it would come down to a couple of things. The bikes are basically hand built, so errors can happen. MG`s have been selling well so new hires are probably messing things up occasionally. Just speculation. I would rather own a MG than a soulless bike from elsewhere.
kk

[guzzisteve]

I would just get rid of all the evap crap, bike will run better.

[Beavis]

If I had to guess I think it would come down to a couple of things. The bikes are basically hand built, so errors can happen. MG`s have been selling well so new hires are probably messing things up occasionally. Just speculation. I would rather own a MG than a soulless bike from elsewhere.
kk

[Roebling3]

Poor interpretation on my part?
I thought the spark plug had broken and the cylinder caught most of the ceramics.

Deadly, on that cylinder, for certain, Valve, cylinder wall, piston.  R3~

[Beavis]

Well , after sometime , the noise still there , so it was needed some deeper dig .

Noticed that my intake valve lash was getting out of spec , after 4 attempts (0.13 mm) , always getting alot of lash after some kms .

Took my push rods out and check it for some bending ...

https://youtu.be/HlcelpCUdss

https://www.youtube.com/watch?v=FrEsqgiNSP8

uploaded this video ( sorry my english , not my native language) .

Need some expert thoughts.

The tip ( tappet side ) is swinging , and have some slight marks (scratches) along the push rod.

[Frenchfrog]

Not an expert at all but that is bent.Do you have a good engineering workshop near who could check and maybe straighten it ?