750 Breva Engine noise |
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NevilleG
Falcone Joined: 07 Nov 2018 Location: Nairn Scotland Status: Offline Points: 72 |
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Posted: 07 Nov 2018 at 14:20 |
I'm new to this forum, but not new to Guzzi bikes having owned both a 750S3 and a California before my current Breva 750, but the engine on this one emits a peculiar deep knocking noise when hot and with the clutch pulled in, which wasn't present on the other models.
I bought this bike in June this year to replace an identical one that I had bought in May, but as that first one had a faulty clutch thrust bearing, it was bought back by the seller. However, that one also made the same noise, but it was much louder than this second one. It's not there when the engine is cold, only when fully warmed up. Does anyone know what might be causing the noise, assuming it is common to all the models that use this engine - Nevada's, V7's etc. I have taken a video of the noise made by the first bike, where it was more pronounced, which I could send to anyone for a diagnosis if they would like to send me a Private Message. Many thanks for your help. Nev. |
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V7II Stone
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Mr Grumpy
Senior Member Joined: 22 Jun 2018 Location: Grantham Status: Offline Points: 149 |
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Mine does it too - thought it was 'normal' along with all the other clattering that goes on.
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nab301
Senior Member Joined: 29 Oct 2017 Location: Dublin Ireland Status: Offline Points: 443 |
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My B750 can get a bit noisy when very hot ( pulling the clutch ) I wouldn't describe it as a knock though ... maybe more of a rattle ?
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Nigel
Keep smiling , it makes people wonder what you've been up to! '19 CB125F, '18 DL250 SUZUKI V STROM,'99 Bmw R1100S, '03Bullet 65 500, '93 MZ301 Saxon fun (offroad) |
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NevilleG
Falcone Joined: 07 Nov 2018 Location: Nairn Scotland Status: Offline Points: 72 |
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No, mine is definitely a deep persistent knock, much like a knackered main bearing does. If yours is a rattle, that must be something else. Nev. |
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V7II Stone
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Brian UK
Moderator Group Joined: 13 May 2014 Location: Surrey Status: Offline Points: 17641 |
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I assume this is only on tickover? The V twin does present problems with uneven firing strokes particularly at tickover, and this can cause a deep knocking sound from the gearbox.
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Brian.
Better 5 minutes late in this world than years early in the next. |
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NevilleG
Falcone Joined: 07 Nov 2018 Location: Nairn Scotland Status: Offline Points: 72 |
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I know the gearbox is prone to rattle a lot when hot and an uneven tickover makes it worse, but pulling the clutch in disengages the gearbox and stops the rotation and any rattle. By careful throttle valve and air-bypass balancing, I have got my tickover very even, so that is now pretty minimal. This deep knocking noise definitely comes from the engine and seems more prevalent at the front. My guess is that it might be crankshaft end-float, after the load of the gearbox is removed, but I would be interested to hear if it is common to all 750 models and years. My Breva is a 2007 model. Nev. |
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V7II Stone
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Bugsy
Falcone Joined: 08 Oct 2018 Location: N Status: Offline Points: 66 |
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Nev - my 2007 Breva 750 does not make any worrying noises (so I hope this commment doesn't hex it!) and I run old British bikes so I know all about rattles and knocking. However my Breva has only 5,600 miles and some of these bikes do huge mileages with good regular maintenance. So, if I may ask, has your bike done a lot of miles and has it had regular oil changes do you know?
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Brian UK
Moderator Group Joined: 13 May 2014 Location: Surrey Status: Offline Points: 17641 |
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Not heard of any probems on the B750 in that area. Some later V7s had a problem with crankshaft endfloat but that was much later on.
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Brian.
Better 5 minutes late in this world than years early in the next. |
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NevilleG
Falcone Joined: 07 Nov 2018 Location: Nairn Scotland Status: Offline Points: 72 |
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Hi Ron, The Breva I have now has done arround 17000 miles and the one that I had before that, where the noise was more pronounced, had done 25000. This one has been very carefully maintained by the previous owner and he had put records of the oil changes etc. in with the handbook. I'm pretty confident that it not a big problem and she will do many more miles without any further issues, especially as both bikes had this noise and other people have it on their bikes to. However, I would still like to know how common it is and, moreover, if anyone knows what causes it. Having had an assortment of bikes since 1954 dating from my first 1928 Ariel 500, I'm also very familiar with the assortment of engine noises that come with them, but I can't put my finger on what might be causing this one, particularly as it wasn't present on my similarly designed previous Guzzi's Thanks for all your contributions so far. Nev. |
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V7II Stone
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rapheal
Senior Member Joined: 13 Nov 2014 Location: west country Status: Offline Points: 573 |
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check that the exhaust system is secure, the heat shields can work loose and rattle, as can the silencer exhaust pipe joints
mines 15 years old now, if it stops rattling I start to worry !! |
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NevilleG
Falcone Joined: 07 Nov 2018 Location: Nairn Scotland Status: Offline Points: 72 |
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Hi Rapheal. I am aware that the two heat shields on the silencers come loose and rattle, having tightened them up twice already, as well as all the other joints. Perhaps I should make it clear that this noise is a KNOCK, you know, "DONK_DONK_DONK," consistent with each firing stroke, not a RATTLE. The noise is coming from low down at the front of the engine and, I repeat, is only there when the engine is HOT with THE CLUTCH IS PULLED IN and is most noticeable at tickover ! In my experience, having owned two previous ones, Guzzi engines are normally extremely quiet mechanically, in particular my California with its hydraulic tappets, but the 750S3 was almost as quiet. The gearbox's were another matter !! Thanks anyway. Nev. |
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V7II Stone
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Bugsy
Falcone Joined: 08 Oct 2018 Location: N Status: Offline Points: 66 |
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It is tempting to suggest that normal riding involves the clutch being engaged (out rather than pulled in) and well above tickover. If the bike is OK under those riding conditions then is there much wrong? On most bikes I have known there have been a different set of noises when ticking over, clutch pulled and in neutral when compared with riding along.
None of this is an answer, I know. Have you tried the stethoscope test or perhaps the long screwdriver held to crankcase and ear, to gain a localised sound impression?
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NevilleG
Falcone Joined: 07 Nov 2018 Location: Nairn Scotland Status: Offline Points: 72 |
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Hi Bugsy. As I said in one of my previous replies, I am more curious to know what causes it and if it is common to all the V7 models, than worried about it. One person has said his bike also makes the noise, but I was hoping there might be some Guzzi technician out there that could a) Tell me what causes it and B) Tell me if it is a problem that will need attention in the long term. I have tried to pin-point it with the screwdriver in the ear technique, but it seems to transmit throughout the crankcase, probably because it is a low frequency. You sound like someone who is well experienced with motorcycle mechanics and if you would like to send me a Private Message containing your email address, I can send you the two videos that I made of the noise. Nev. |
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V7II Stone
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Brian UK
Moderator Group Joined: 13 May 2014 Location: Surrey Status: Offline Points: 17641 |
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There was a crankshaft thrust bearing problem on a few of the later v7 models, but never heard of any recurring problem on the B750.
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Brian.
Better 5 minutes late in this world than years early in the next. |
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Vegas Pete
Falcone Joined: 21 Nov 2017 Location: Las Vegas, NV. Status: Offline Points: 23 |
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I have a 2010 V7c that makes a knocking noise with the clutch pulled in at idle. At first I thought it sounded like excessive crankshaft end float, based on previous experience with air cooled VWs, but l finally came to the conclusion that it was the clutch disc banging back and forth on the hub splines. The crank does a lot of speeding up and slowing down between power strokes at idle on these things, and with the clutch disengaged the disc is free to float on the splines. As soon as the clutch plate is pressed into contact with the flywheel and can no longer float, the sound stops.
That's my story and I'm sticking with it. Vegas Pete.
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2010 V7 Classic, 2005 Ural Gearup, 1980 Yamaha DT175, 1973 Rokon RT-140, 1969 Rokon MkIII
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