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750 Breva Engine noise

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NevilleG View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote NevilleG Quote  Post ReplyReply Direct Link To This Post Topic: 750 Breva Engine noise
    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.
Breva 750
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Mr Grumpy View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mr Grumpy Quote  Post ReplyReply Direct Link To This Post Posted: 07 Nov 2018 at 14:53
Mine does it too - thought it was 'normal' along with all the other clattering that goes on.
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nab301 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote nab301 Quote  Post ReplyReply Direct Link To This Post Posted: 07 Nov 2018 at 19:37
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 ?


Nigel
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NevilleG View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote NevilleG Quote  Post ReplyReply Direct Link To This Post Posted: 08 Nov 2018 at 11:20
Originally posted by nab301 nab301 wrote:

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 ?





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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Brian UK View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 08 Nov 2018 at 14:50
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.
Brian.

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NevilleG View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote NevilleG Quote  Post ReplyReply Direct Link To This Post Posted: 09 Nov 2018 at 13:18
Originally posted by Brian UK Brian UK wrote:

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.


   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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Bugsy View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bugsy Quote  Post ReplyReply Direct Link To This Post Posted: 09 Nov 2018 at 13:30
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?
Ron

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Brian UK View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 09 Nov 2018 at 14:07
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.
Brian.

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NevilleG View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote NevilleG Quote  Post ReplyReply Direct Link To This Post Posted: 11 Nov 2018 at 12:03
Originally posted by Bugsy Bugsy wrote:

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?


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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rapheal View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote rapheal Quote  Post ReplyReply Direct Link To This Post Posted: 7 hours 58 minutes ago at 23:07
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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